<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>RT60 Reverberation Decay Curve</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    }

    body {
      background: #ffffff;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
    }

    .wrapper {
      width: 100%;
      max-width: 580px;
      display: flex;
      flex-direction: column;
      gap: 12px;
    }

    .controls {
      display: flex;
      flex-direction: column;
      gap: 10px;
      width: 100%;
    }

    .presets {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 8px;
    }

    @media (max-width: 440px) {
      .presets {
        grid-template-columns: repeat(2, 1fr);
      }
    }

    .preset-btn {
      padding: 8px 6px;
      background: #f8fafc;
      border: 1.5px solid #cbd5e1;
      border-radius: 8px;
      font-size: 13px;
      line-height: 1.3;
      font-weight: 600;
      color: #1e2945;
      cursor: pointer;
      transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
      text-align: center;
    }

    .preset-btn span {
      display: block;
      font-size: 11.5px;
      font-weight: 500;
      color: #64748b;
    }

    .preset-btn:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }

    .preset-btn.active {
      background: #10b981;
      color: #ffffff;
      border-color: #10b981;
    }

    .preset-btn.active span {
      color: #e6fcf5;
    }

    .slider-row {
      display: flex;
      align-items: center;
      gap: 12px;
      font-size: 14px;
      font-weight: 600;
      background: #f8fafc;
      padding: 8px 12px;
      border-radius: 8px;
    }

    .slider-row label {
      white-space: nowrap;
      color: #1e2945;
    }

    input[type="range"] {
      flex: 1;
      accent-color: #10b981;
      cursor: pointer;
      height: 6px;
      min-width: 80px;
    }

    .value-badge {
      color: #059669;
      font-weight: 700;
      font-size: 15px;
      min-width: 46px;
      text-align: right;
    }

    .graph-container {
      width: 100%;
      position: relative;
    }

    svg {
      width: 100%;
      height: auto;
      display: block;
      overflow: visible;
    }

    .axis-line {
      stroke: #64748b;
      stroke-width: 1.5;
    }

    .grid-line {
      stroke: #f1f5f9;
      stroke-width: 1;
    }

    .ref-line {
      stroke: #94a3b8;
      stroke-width: 1.5;
      stroke-dasharray: 4 4;
    }

    .rt60-line {
      stroke: #2563eb;
      stroke-width: 1.5;
      stroke-dasharray: 4 4;
    }

    .axis-label {
      fill: #64748b;
      font-size: 12px;
      font-weight: 500;
    }

    .main-label {
      fill: #1e2945;
      font-size: 13px;
      font-weight: 700;
    }

    .decay-curve {
      fill: none;
      stroke: #10b981;
      stroke-width: 3.5;
      stroke-linecap: round;
      stroke-linejoin: round;
    }

    .decay-fill {
      fill: rgba(16, 185, 129, 0.1);
    }

    .spike-line {
      stroke: #10b981;
      stroke-width: 3.5;
      stroke-linecap: round;
    }

    .marker-dot {
      fill: #10b981;
      stroke: #ffffff;
      stroke-width: 2;
    }

    .rt60-tag {
      fill: #1e2945;
      font-size: 13px;
      font-weight: 700;
    }

    @media (max-width: 380px) {
      .slider-row {
        font-size: 13px;
        gap: 8px;
        padding: 6px 10px;
      }
      .value-badge {
        font-size: 14px;
        min-width: 40px;
      }
    }
  </style>
</head>
<body>
  <div class="wrapper">
    <div class="controls">
      <div class="presets">
        <button class="preset-btn active" data-val="0.8">Tight Room<span>0.8s</span></button>
        <button class="preset-btn" data-val="1.6">Studio<span>1.6s</span></button>
        <button class="preset-btn" data-val="2.4">Concert Hall<span>2.4s</span></button>
        <button class="preset-btn" data-val="3.5">Cathedral<span>3.5s</span></button>
      </div>
      <div class="slider-row">
        <label for="rtSlider">RT60 Time:</label>
        <input type="range" id="rtSlider" min="0.8" max="3.5" step="0.1" value="0.8">
        <span id="rtValue" class="value-badge">0.8s</span>
      </div>
    </div>

    <div class="graph-container">
      <svg viewBox="0 0 580 340" id="graphSvg">
        
        <g id="gridY"></g>
        
        
        <g id="gridX"></g>

        
        <line id="ref60Line" class="ref-line" x1="75" y1="245" x2="540" y2="245" />
        <text x="536" y="238" text-anchor="end" fill="#64748b" font-size="12" font-weight="600">-60 dB Target (1/1,000,000 Energy)</text>

        
        <path id="decayArea" class="decay-fill" />

        
        <line class="axis-line" x1="75" y1="280" x2="540" y2="280" />
        <line class="axis-line" x1="75" y1="35" x2="75" y2="280" />

        
        <text x="307" y="328" text-anchor="middle" class="main-label">Time (seconds)</text>
        <text transform="rotate(-90)" x="-157" y="20" text-anchor="middle" class="main-label">Sound Level (dB)</text>

        
        <line id="rtDropLine" class="rt60-line" x1="75" y1="35" x2="75" y2="280" />

        
        <line class="spike-line" x1="75" y1="280" x2="75" y2="35" />
        <circle cx="75" cy="35" r="4.5" class="marker-dot" />
        <text x="85" y="40" class="main-label" fill="#059669">Direct Sound (0 dB)</text>

        
        <path id="curvePath" class="decay-curve" />

        
        <circle id="rtDot" cx="178" cy="245" r="5.5" fill="#2563eb" stroke="#ffffff" stroke-width="2" />
        <text id="rtLabel" x="178" y="270" text-anchor="middle" class="rt60-tag">RT60 = 0.8s</text>
      </svg>
    </div>
  </div>

  <script>
    const slider = document.getElementById('rtSlider');
    const rtValueDisplay = document.getElementById('rtValue');
    const presetBtns = document.querySelectorAll('.preset-btn');
    const curvePath = document.getElementById('curvePath');
    const decayArea = document.getElementById('decayArea');
    const rtDropLine = document.getElementById('rtDropLine');
    const rtDot = document.getElementById('rtDot');
    const rtLabel = document.getElementById('rtLabel');
    const gridY = document.getElementById('gridY');
    const gridX = document.getElementById('gridX');

    // Graph coordinate mappings with generous left margin for labels
    const xMin = 0, xMax = 4.0;
    const yMin = 0, yMax = -70; // dB
    const svgLeft = 75, svgRight = 540;
    const svgTop = 35, svgBottom = 280;

    function getX(t) {
      return svgLeft + (t - xMin) / (xMax - xMin) * (svgRight - svgLeft);
    }

    function getY(db) {
      return svgTop + (0 - db) / (0 - yMax) * (svgBottom - svgTop);
    }

    // Render Grid & Ticks
    for (let db = 0; db >= -70; db -= 10) {
      const y = getY(db);
      gridY.innerHTML += `
        <line class="grid-line" x1="${svgLeft}" y1="${y}" x2="${svgRight}" y2="${y}" />
        <text class="axis-label" x="${svgLeft - 10}" y="${y + 4}" text-anchor="end">${db} dB</text>
      `;
    }

    for (let t = 0; t <= 4.0; t += 1.0) {
      const x = getX(t);
      gridX.innerHTML += `
        <line class="grid-line" x1="${x}" y1="${svgTop}" x2="${x}" y2="${svgBottom}" />
        <text class="axis-label" x="${x}" y="${svgBottom + 18}" text-anchor="middle">${t.toFixed(1)}s</text>
      `;
    }

    function updateGraph(rt60) {
      rtValueDisplay.textContent = parseFloat(rt60).toFixed(1) + 's';

      // RT60 point: dB drops 60 dB at t = rt60
      const yAtDrop = -60;
      const xAtDrop = getX(rt60);
      const yPos60 = getY(yAtDrop);

      // Path data
      const pts = [];
      const steps = 40;
      const tEnd = Math.min(4.0, rt60 * (70 / 60)); // extend to -70dB

      for (let i = 0; i <= steps; i++) {
        const t = (tEnd / steps) * i;
        const db = -(60 / rt60) * t;
        if (db < -70) break;
        pts.push({ x: getX(t), y: getY(db) });
      }

      let d = `M ${pts[0].x} ${pts[0].y}`;
      for (let i = 1; i < pts.length; i++) {
        d += ` L ${pts[i].x.toFixed(1)} ${pts[i].y.toFixed(1)}`;
      }

      curvePath.setAttribute('d', d);

      // Area fill path
      const lastPt = pts[pts.length - 1];
      const fillD = `${d} L ${lastPt.x.toFixed(1)} ${svgBottom} L ${svgLeft} ${svgBottom} Z`;
      decayArea.setAttribute('d', fillD);

      // RT60 Drop Line & Markers
      rtDropLine.setAttribute('x1', xAtDrop);
      rtDropLine.setAttribute('y1', svgTop);
      rtDropLine.setAttribute('x2', xAtDrop);
      rtDropLine.setAttribute('y2', svgBottom);

      rtDot.setAttribute('cx', xAtDrop);
      rtDot.setAttribute('cy', yPos60);

      // Position label ensuring it doesn't clip right boundary
      const labelX = Math.min(xAtDrop, 475);
      rtLabel.setAttribute('x', labelX);
      rtLabel.setAttribute('y', svgBottom - 8);
      rtLabel.textContent = `RT60 = ${parseFloat(rt60).toFixed(1)}s`;

      // Update preset buttons state
      presetBtns.forEach(btn => {
        if (Math.abs(parseFloat(btn.dataset.val) - parseFloat(rt60)) < 0.05) {
          btn.classList.add('active');
        } else {
          btn.classList.remove('active');
        }
      });
    }

    slider.addEventListener('input', (e) => {
      updateGraph(parseFloat(e.target.value));
    });

    presetBtns.forEach(btn => {
      btn.addEventListener('click', () => {
        const val = parseFloat(btn.dataset.val);
        slider.value = val;
        updateGraph(val);
      });
    });

    // Initial render
    updateGraph(0.8);
  </script>
</body>
</html>

Reverb Parameters: Pre-Delay, Decay Time, Damping, and Diffusion

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      background: #f8fafc;
      color: #1e2945;
      font-family: system-ui, -apple-system, sans-serif;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
      padding: 12px;
      user-select: none;
    }
    .graph-box {
      width: 100%;
      max-width: 600px;
      position: relative;
    }
    svg {
      width: 100%;
      height: auto;
      display: block;
      overflow: visible;
    }
    .legend {
      display: flex;
      justify-content: center;
      gap: 16px;
      flex-wrap: wrap;
      margin-top: 8px;
      font-size: 14px;
      font-weight: 600;
    }
    .item {
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .badge {
      width: 16px;
      height: 4px;
      border-radius: 2px;
    }
    .btn-sound {
      margin-top: 10px;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 20px;
      padding: 6px 14px;
      font-size: 14px;
      font-weight: 600;
      color: #1e2945;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      box-shadow: 0 1px 3px rgba(0,0,0,0.05);
    }
    .btn-sound:active {
      background: #f1f5f9;
    }
  </style>
</head>
<body>

  <div class="graph-box">
    <svg viewBox="0 0 600 320">
      <defs>
        
        <linearGradient id="grad-low" x1="0" y1="0" x2="0" y2="1">
          <stop offset="0%" stop-color="#2563eb" stop-opacity="0.35" />
          <stop offset="100%" stop-color="#2563eb" stop-opacity="0.02" />
        </linearGradient>
        <linearGradient id="grad-mid" x1="0" y1="0" x2="0" y2="1">
          <stop offset="0%" stop-color="#8b5cf6" stop-opacity="0.35" />
          <stop offset="100%" stop-color="#8b5cf6" stop-opacity="0.02" />
        </linearGradient>
        <linearGradient id="grad-high" x1="0" y1="0" x2="0" y2="1">
          <stop offset="0%" stop-color="#ea580c" stop-opacity="0.4" />
          <stop offset="100%" stop-color="#ea580c" stop-opacity="0.02" />
        </linearGradient>
        <linearGradient id="grad-absorb" x1="0" y1="0" x2="1" y2="0">
          <stop offset="0%" stop-color="#ffedd5" stop-opacity="0.8" />
          <stop offset="100%" stop-color="#ffedd5" stop-opacity="0.1" />
        </linearGradient>
      </defs>

      
      
      <polygon points="70,120 170,40 570,40 470,120" fill="#f1f5f9" stroke="#e2e8f0" stroke-width="1" />
      <line x1="120" y1="80" x2="520" y2="80" stroke="#e2e8f0" stroke-width="1" stroke-dasharray="3,3" />

      
      <polygon points="70,260 170,180 570,180 470,260" fill="#f8fafc" stroke="#cbd5e1" stroke-width="1.5" />
      
      
      
      <line x1="163" y1="260" x2="263" y2="180" stroke="#fed7aa" stroke-width="1.5" stroke-dasharray="2,2" />
      
      <line x1="203" y1="260" x2="303" y2="180" stroke="#e2e8f0" stroke-width="1" />
      
      <line x1="310" y1="260" x2="410" y2="180" stroke="#ddd6fe" stroke-width="1.5" stroke-dasharray="2,2" />
      
      <line x1="337" y1="260" x2="437" y2="180" stroke="#e2e8f0" stroke-width="1" />
      
      <line x1="403" y1="260" x2="503" y2="180" stroke="#bfdbfe" stroke-width="1.5" stroke-dasharray="2,2" />

      
      <path d="M 170,90 
               C 210,105 270,135 340,155 
               C 410,172 470,178 503,180 
               L 570,180 L 170,180 Z" 
            fill="url(#grad-low)" />
      <path d="M 170,90 
               C 210,105 270,135 340,155 
               C 410,172 470,178 503,180 
               L 570,180" 
            fill="none" stroke="#2563eb" stroke-width="3" stroke-linecap="round" />
      <circle cx="503" cy="180" r="4" fill="#2563eb" />

      
      <path d="M 120,130 
               C 160,155 220,190 280,208 
               C 330,217 380,219.5 410,220 
               L 520,220 L 120,220 Z" 
            fill="url(#grad-mid)" />
      <path d="M 120,130 
               C 160,155 220,190 280,208 
               C 330,217 380,219.5 410,220 
               L 520,220" 
            fill="none" stroke="#8b5cf6" stroke-width="3" stroke-linecap="round" />
      <circle cx="410" cy="220" r="4" fill="#8b5cf6" />

      
      
      <path d="M 70,170 
               C 90,205 120,245 163,260 
               L 163,260 L 70,260 Z" 
            fill="url(#grad-high)" />
      <path d="M 70,170 
               C 90,205 120,245 163,260 
               L 470,260" 
            fill="none" stroke="#ea580c" stroke-width="3" stroke-dasharray="6,4" stroke-linecap="round" />
      <circle cx="163" cy="260" r="4" fill="#ea580c" />

      
      
      <line x1="70" y1="260" x2="70" y2="160" stroke="#1e2945" stroke-width="2" />
      <text x="62" y="165" fill="#64748b" font-size="14" font-weight="700" text-anchor="end">0 dB</text>
      <text x="62" y="264" fill="#64748b" font-size="14" font-weight="700" text-anchor="end">-60 dB</text>
      <text x="40" y="210" fill="#1e2945" font-size="14" font-weight="700" transform="rotate(-90 40 210)" text-anchor="middle">Amplitude</text>

      
      <line x1="70" y1="260" x2="470" y2="260" stroke="#1e2945" stroke-width="2" />
      <text x="70" y="280" fill="#64748b" font-size="14" font-weight="700" text-anchor="middle">0s</text>
      <text x="203" y="280" fill="#64748b" font-size="14" font-weight="700" text-anchor="middle">1.0s</text>
      <text x="337" y="280" fill="#64748b" font-size="14" font-weight="700" text-anchor="middle">2.0s</text>
      <text x="470" y="280" fill="#64748b" font-size="14" font-weight="700" text-anchor="middle">3.0s</text>
      <text x="270" y="304" fill="#1e2945" font-size="15" font-weight="700" text-anchor="middle">Time (seconds)</text>

      
      <g transform="translate(145, 140)">
        <rect x="0" y="0" width="168" height="32" rx="6" fill="#fff" stroke="#ea580c" stroke-width="1.5" filter="drop-shadow(0 2px 4px rgba(0,0,0,0.06))" />
        <text x="84" y="20" fill="#ea580c" font-size="14" font-weight="700" text-anchor="middle">HF Absorption (Damping)</text>
        
        <line x1="0" y1="16" x2="-35" y2="45" stroke="#ea580c" stroke-width="1.5" stroke-dasharray="3,2" />
        <circle cx="-35" cy="45" r="3" fill="#ea580c" />
      </g>
    </svg>

    <div class="legend">
      <div class="item" style="color: #2563eb;">
        <span class="badge" style="background: #2563eb;"></span>
        <span>Low (250 Hz) • 2.5s</span>
      </div>
      <div class="item" style="color: #8b5cf6;">
        <span class="badge" style="background: #8b5cf6;"></span>
        <span>Mid (1 kHz) • 1.8s</span>
      </div>
      <div class="item" style="color: #ea580c;">
        <span class="badge" style="background: #ea580c; border-top: 2px dashed #ea580c; height: 0;"></span>
        <span>High (8 kHz) • 0.7s</span>
      </div>
    </div>
  </div>

  <button class="btn-sound" id="playBtn" onclick="playDecayAudio()">
    <span>Audition Damped Reverb</span> 🔊
  </button>

  <script>
    function playDecayAudio() {
      const ctx = new (window.AudioContext || window.webkitAudioContext)();
      const dur = 2.6;
      const buf = ctx.createBuffer(1, ctx.sampleRate * dur, ctx.sampleRate);
      const data = buf.getChannelData(0);

      // Synthesize impulse response with frequency-dependent decay
      for (let i = 0; i < data.length; i++) {
        const t = i / ctx.sampleRate;
        const low = (Math.random() * 2 - 1) * Math.exp(-t / 0.85);   // 2.5s decay
        const mid = (Math.random() * 2 - 1) * Math.exp(-t / 0.55);   // 1.8s decay
        const high = (Math.random() * 2 - 1) * Math.exp(-t / 0.18);  // 0.7s decay (HF damping)
        data[i] = (low * 0.4 + mid * 0.4 + high * 0.5) * 0.25;
      }

      const src = ctx.createBufferSource();
      src.buffer = buf;
      src.connect(ctx.destination);
      src.start();
    }
  </script>

</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Audio Diffusion Comparison</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      background: transparent;
      padding: 8px;
      display: flex;
      flex-direction: column;
      min-height: 100%;
    }

    .grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
      width: 100%;
    }

    @media (max-width: 500px) {
      .grid {
        grid-template-columns: 1fr;
      }
    }

    .column {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 10px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      gap: 8px;
    }

    .column-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
      flex-wrap: wrap;
    }

    .title {
      font-size: 14px;
      font-weight: 700;
      color: #1e2945;
    }

    .badge {
      font-size: 11px;
      font-weight: 600;
      padding: 2px 7px;
      border-radius: 999px;
      white-space: nowrap;
    }

    .badge-low {
      background: #e0f2fe;
      color: #0369a1;
      border: 1px solid #bae6fd;
    }

    .badge-high {
      background: #ecfeff;
      color: #0e7490;
      border: 1px solid #a5f3fc;
    }

    .display-box {
      background: #ffffff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 8px;
      display: flex;
      flex-direction: column;
      gap: 6px;
    }

    .label-row {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 6px;
      flex-wrap: wrap;
      font-size: 10px;
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      color: #64748b;
      line-height: 1.2;
    }

    .label-row span {
      white-space: nowrap;
    }

    svg {
      width: 100%;
      height: auto;
      display: block;
    }

    .footer-tag {
      font-size: 11px;
      font-weight: 600;
      text-align: center;
      padding: 6px 4px;
      border-radius: 6px;
      line-height: 1.3;
    }

    .tag-low {
      background: #f1f5f9;
      color: #2563eb;
    }

    .tag-high {
      background: #f0fdfa;
      color: #0891b2;
    }

    .listen-btn {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      padding: 7px 10px;
      font-size: 12px;
      font-weight: 600;
      color: #1e2945;
      cursor: pointer;
      user-select: none;
      transition: background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
    }

    .listen-btn:hover {
      background: #f1f5f9;
      border-color: #94a3b8;
    }

    .listen-btn:active {
      background: #e2e8f0;
    }

    .listen-btn.playing {
      background: #e0f2fe;
      border-color: #06b6d4;
      color: #0369a1;
    }
  </style>
</head>
<body>

  <div class="grid">
    
    <div class="column">
      <div class="column-header">
        <span class="title">Low Diffusion</span>
        <span class="badge badge-low">Discrete</span>
      </div>

      
      <div class="display-box">
        <div class="label-row">
          <span>Waveform Envelope</span>
          <span>Time →</span>
        </div>
        <svg viewBox="0 0 200 44" preserveAspectRatio="none">
          
          <path d="M 0,22 
                   Q 8,3 12,22 
                   Q 22,6 28,22 
                   Q 40,9 46,22 
                   Q 62,11 70,22 
                   Q 88,13 96,22 
                   Q 118,15 126,22 
                   Q 150,18 158,22 
                   L 200,22" 
                fill="none" stroke="#2563eb" stroke-width="2" stroke-linejoin="round" />
          <path d="M 0,22 
                   Q 8,41 12,22 
                   Q 22,38 28,22 
                   Q 40,35 46,22 
                   Q 62,33 70,22 
                   Q 88,31 96,22 
                   Q 118,29 126,22 
                   Q 150,26 158,22 
                   L 200,22" 
                fill="none" stroke="#2563eb" stroke-width="2" stroke-linejoin="round" />
        </svg>
      </div>

      
      <div class="display-box">
        <div class="label-row">
          <span>Impulse Reflections</span>
          <span>Spaced Spikes</span>
        </div>
        <svg viewBox="0 0 200 56" preserveAspectRatio="none">
          
          <line x1="0" y1="52" x2="200" y2="52" stroke="#cbd5e1" stroke-width="1.5" />
          
          
          <line x1="12" y1="52" x2="12" y2="8" stroke="#2563eb" stroke-width="3" stroke-linecap="round" />
          <line x1="28" y1="52" x2="28" y2="14" stroke="#2563eb" stroke-width="2.5" stroke-linecap="round" />
          <line x1="48" y1="52" x2="48" y2="21" stroke="#2563eb" stroke-width="2.5" stroke-linecap="round" />
          <line x1="72" y1="52" x2="72" y2="27" stroke="#2563eb" stroke-width="2" stroke-linecap="round" />
          <line x1="100" y1="52" x2="100" y2="34" stroke="#2563eb" stroke-width="2" stroke-linecap="round" />
          <line x1="132" y1="52" x2="132" y2="40" stroke="#2563eb" stroke-width="1.5" stroke-linecap="round" />
          <line x1="168" y1="52" x2="168" y2="46" stroke="#2563eb" stroke-width="1.5" stroke-linecap="round" />
        </svg>
      </div>

      <div class="footer-tag tag-low">Fluttery / Grainy / Distinct</div>
      
      <button class="listen-btn" id="btnLow">
        <span>▶</span> Listen (Grainy)
      </button>
    </div>

    
    <div class="column">
      <div class="column-header">
        <span class="title">High Diffusion</span>
        <span class="badge badge-high">Dense</span>
      </div>

      
      <div class="display-box">
        <div class="label-row">
          <span>Waveform Envelope</span>
          <span>Time →</span>
        </div>
        <svg viewBox="0 0 200 44" preserveAspectRatio="none">
          
          <path d="M 0,22 Q 25,3 70,11 T 200,22 L 200,22 Q 130,33 70,33 T 0,22 Z" 
                fill="#ecfeff" stroke="none" />
          
          <path d="M 0,22 Q 25,3 70,11 T 200,22" 
                fill="none" stroke="#06b6d4" stroke-width="2" stroke-linecap="round" />
          <path d="M 0,22 Q 25,41 70,33 T 200,22" 
                fill="none" stroke="#06b6d4" stroke-width="2" stroke-linecap="round" />
          
          <path d="M 2,22 L 6,16 L 10,27 L 15,14 L 20,29 L 26,17 L 32,26 L 40,18 L 50,25 L 65,20 L 80,24 L 100,21 L 130,23 L 170,22" 
                fill="none" stroke="#0891b2" stroke-width="1" opacity="0.6" />
        </svg>
      </div>

      
      <div class="display-box">
        <div class="label-row">
          <span>Impulse Reflections</span>
          <span>Particle Cloud</span>
        </div>
        <svg viewBox="0 0 200 56" preserveAspectRatio="none" id="cloudSvg">
          
          <line x1="0" y1="52" x2="200" y2="52" stroke="#cbd5e1" stroke-width="1.5" />
          
        </svg>
      </div>

      <div class="footer-tag tag-high">Smooth / Continuous Wash</div>

      <button class="listen-btn" id="btnHigh">
        <span>▶</span> Listen (Smooth)
      </button>
    </div>
  </div>

  <script>
    // Generate high diffusion dense impulse spikes
    const svg = document.getElementById('cloudSvg');
    for (let x = 4; x <= 196; x += 1.8) {
      const decay = Math.exp(-x / 65);
      const height = (Math.random() * 0.4 + 0.6) * 44 * decay;
      const y2 = 52 - height;
      const opacity = 0.35 + 0.65 * decay;
      
      const line = document.createElementNS('http://www.w3.org/2000/svg', 'line');
      line.setAttribute('x1', x);
      line.setAttribute('y1', 52);
      line.setAttribute('x2', x);
      line.setAttribute('y2', Math.max(8, y2));
      line.setAttribute('stroke', '#06b6d4');
      line.setAttribute('stroke-width', '1.2');
      line.setAttribute('stroke-linecap', 'round');
      line.setAttribute('opacity', opacity);
      svg.appendChild(line);
    }

    // Web Audio Synthesizer for Low vs High Diffusion sound
    let audioCtx = null;

    function getAudioContext() {
      if (!audioCtx) {
        audioCtx = new (window.AudioContext || window.webkitAudioContext)();
      }
      if (audioCtx.state === 'suspended') {
        audioCtx.resume();
      }
      return audioCtx;
    }

    function playLowDiffusion() {
      const ctx = getAudioContext();
      const btn = document.getElementById('btnLow');
      btn.classList.add('playing');

      const delays = [0, 0.07, 0.15, 0.24, 0.36, 0.50, 0.68, 0.88];
      const gains = [0.8, 0.6, 0.45, 0.35, 0.25, 0.18, 0.12, 0.06];

      delays.forEach((t, i) => {
        const osc = ctx.createOscillator();
        const gain = ctx.createGain();
        osc.type = 'triangle';
        osc.frequency.setValueAtTime(440 + (i % 2 === 0 ? 80 : -40), ctx.currentTime + t);
        
        gain.gain.setValueAtTime(gains[i] * 0.4, ctx.currentTime + t);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + t + 0.04);
        
        osc.connect(gain);
        gain.connect(ctx.destination);
        
        osc.start(ctx.currentTime + t);
        osc.stop(ctx.currentTime + t + 0.05);
      });

      setTimeout(() => btn.classList.remove('playing'), 1000);
    }

    function playHighDiffusion() {
      const ctx = getAudioContext();
      const btn = document.getElementById('btnHigh');
      btn.classList.add('playing');

      const bufferSize = Math.floor(ctx.sampleRate * 1.2);
      const buffer = ctx.createBuffer(1, bufferSize, ctx.sampleRate);
      const data = buffer.getChannelData(0);
      for (let i = 0; i < bufferSize; i++) {
        data[i] = Math.random() * 2 - 1;
      }

      const noise = ctx.createBufferSource();
      noise.buffer = buffer;

      const filter = ctx.createBiquadFilter();
      filter.type = 'lowpass';
      filter.frequency.setValueAtTime(2200, ctx.currentTime);
      filter.frequency.exponentialRampToValueAtTime(400, ctx.currentTime + 1.2);

      const gain = ctx.createGain();
      gain.gain.setValueAtTime(0.35, ctx.currentTime);
      gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 1.2);

      noise.connect(filter);
      filter.connect(gain);
      gain.connect(ctx.destination);

      noise.start(ctx.currentTime);
      noise.stop(ctx.currentTime + 1.2);

      setTimeout(() => btn.classList.remove('playing'), 1200);
    }

    document.getElementById('btnLow').addEventListener('click', playLowDiffusion);
    document.getElementById('btnHigh').addEventListener('click', playHighDiffusion);
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Reverb Parameters</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, sans-serif;
      color: #1e2945;
      background: #ffffff;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 12px;
      user-select: none;
    }

    /* Parameter Knobs Grid */
    .controls-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 8px;
    }

    @media (max-width: 480px) {
      .controls-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }

    .knob-tile {
      background: #f8fafc;
      border: 1.5px solid #e2e8f0;
      border-radius: 10px;
      padding: 8px 6px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      cursor: pointer;
      transition: border-color 0.2s, background-color 0.2s, box-shadow 0.2s;
    }

    .knob-tile:hover {
      background: #f1f5f9;
    }

    .knob-tile.active {
      border-color: #0284c7;
      background: #f0f9ff;
      box-shadow: 0 0 0 1px #0284c7;
    }

    .knob-svg {
      width: 46px;
      height: 46px;
      margin-bottom: 4px;
    }

    .knob-track {
      fill: none;
      stroke: #cbd5e1;
      stroke-width: 5;
      stroke-linecap: round;
    }

    .knob-fill {
      fill: none;
      stroke: #0284c7;
      stroke-width: 5;
      stroke-linecap: round;
      transition: stroke-dasharray 0.3s ease;
    }

    .param-title {
      font-size: 11px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      color: #475569;
    }

    .param-value {
      font-size: 13px;
      font-weight: 700;
      color: #0369a1;
      margin: 1px 0;
    }

    .param-sub {
      font-size: 9px;
      color: #64748b;
      line-height: 1.1;
    }

    /* Display / Spectrogram Area */
    .display-container {
      background: #0f172a;
      border-radius: 10px;
      padding: 10px;
      display: flex;
      flex-direction: column;
      gap: 6px;
      position: relative;
    }

    .display-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 0 4px;
    }

    .display-title {
      font-size: 11px;
      font-weight: 600;
      color: #94a3b8;
      letter-spacing: 0.5px;
    }

    .audio-btn {
      background: #1e293b;
      border: 1px solid #334155;
      color: #38bdf8;
      font-size: 11px;
      font-weight: 600;
      padding: 3px 8px;
      border-radius: 6px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: background 0.2s;
    }

    .audio-btn:hover {
      background: #334155;
    }

    .spectrogram-svg {
      width: 100%;
      height: 150px;
      display: block;
    }

    /* Interactive focus callout text bar */
    .focus-bar {
      background: #f1f5f9;
      border-radius: 6px;
      padding: 6px 10px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      font-size: 11px;
      color: #334155;
    }

    .focus-text {
      font-weight: 600;
    }

    .focus-tag {
      color: #0284c7;
      font-weight: 700;
      text-transform: uppercase;
      font-size: 10px;
    }
  </style>
</head>
<body>

  
  <div class="controls-grid">
    
    <div class="knob-tile active" id="knob-0" onclick="selectParam(0)">
      <svg class="knob-svg" viewBox="0 0 40 40">
        <circle class="knob-track" cx="20" cy="20" r="15" stroke-dasharray="70 25" stroke-dashoffset="-12" />
        <circle class="knob-fill" cx="20" cy="20" r="15" stroke-dasharray="28 66" stroke-dashoffset="-12" />
        <circle cx="20" cy="20" r="11" fill="#e2e8f0" />
        <line x1="20" y1="20" x2="14" y2="10" stroke="#0369a1" stroke-width="2.5" stroke-linecap="round" />
      </svg>
      <span class="param-title">Pre-Delay</span>
      <span class="param-value">42 ms</span>
      <span class="param-sub">Consonants</span>
    </div>

    
    <div class="knob-tile" id="knob-1" onclick="selectParam(1)">
      <svg class="knob-svg" viewBox="0 0 40 40">
        <circle class="knob-track" cx="20" cy="20" r="15" stroke-dasharray="70 25" stroke-dashoffset="-12" />
        <circle class="knob-fill" cx="20" cy="20" r="15" stroke-dasharray="48 46" stroke-dashoffset="-12" />
        <circle cx="20" cy="20" r="11" fill="#e2e8f0" />
        <line x1="20" y1="20" x2="27" y2="11" stroke="#0369a1" stroke-width="2.5" stroke-linecap="round" />
      </svg>
      <span class="param-title">Decay (RT60)</span>
      <span class="param-value">2.4 s</span>
      <span class="param-sub">Hall Size</span>
    </div>

    
    <div class="knob-tile" id="knob-2" onclick="selectParam(2)">
      <svg class="knob-svg" viewBox="0 0 40 40">
        <circle class="knob-track" cx="20" cy="20" r="15" stroke-dasharray="70 25" stroke-dashoffset="-12" />
        <circle class="knob-fill" cx="20" cy="20" r="15" stroke-dasharray="35 60" stroke-dashoffset="-12" />
        <circle cx="20" cy="20" r="11" fill="#e2e8f0" />
        <line x1="20" y1="20" x2="20" y2="9" stroke="#0369a1" stroke-width="2.5" stroke-linecap="round" />
      </svg>
      <span class="param-title">HF Damp</span>
      <span class="param-value">4.5 kHz</span>
      <span class="param-sub">Sibilance</span>
    </div>

    
    <div class="knob-tile" id="knob-3" onclick="selectParam(3)">
      <svg class="knob-svg" viewBox="0 0 40 40">
        <circle class="knob-track" cx="20" cy="20" r="15" stroke-dasharray="70 25" stroke-dashoffset="-12" />
        <circle class="knob-fill" cx="20" cy="20" r="15" stroke-dasharray="58 36" stroke-dashoffset="-12" />
        <circle cx="20" cy="20" r="11" fill="#e2e8f0" />
        <line x1="20" y1="20" x2="30" y2="18" stroke="#0369a1" stroke-width="2.5" stroke-linecap="round" />
      </svg>
      <span class="param-title">Diffusion</span>
      <span class="param-value">85%</span>
      <span class="param-sub">Density</span>
    </div>
  </div>

  
  <div class="display-container">
    <div class="display-header">
      <span class="display-title">TIME-FREQUENCY RESPONSE</span>
      <button class="audio-btn" onclick="playAudition()">Audition 🔊</button>
    </div>

    <svg class="spectrogram-svg" viewBox="0 0 500 160" preserveAspectRatio="none">
      <defs>
        
        <linearGradient id="transientGrad" x1="0" y1="0" x2="0" y2="1">
          <stop offset="0%" stop-color="#38bdf8" stop-opacity="1" />
          <stop offset="100%" stop-color="#0284c7" stop-opacity="0.2" />
        </linearGradient>

        <linearGradient id="reverbTailGrad" x1="0" y1="0" x2="1" y2="0">
          <stop offset="0%" stop-color="#38bdf8" stop-opacity="0.85" />
          <stop offset="35%" stop-color="#0ea5e9" stop-opacity="0.5" />
          <stop offset="70%" stop-color="#0284c7" stop-opacity="0.2" />
          <stop offset="100%" stop-color="#0369a1" stop-opacity="0" />
        </linearGradient>

        <linearGradient id="hfLossGrad" x1="0" y1="0" x2="1" y2="1">
          <stop offset="0%" stop-color="#38bdf8" stop-opacity="0.9" />
          <stop offset="40%" stop-color="#0284c7" stop-opacity="0.4" />
          <stop offset="100%" stop-color="#0f172a" stop-opacity="0" />
        </linearGradient>
      </defs>

      
      <line x1="30" y1="130" x2="490" y2="130" stroke="#334155" stroke-width="1" />
      <line x1="30" y1="80" x2="490" y2="80" stroke="#1e293b" stroke-width="1" stroke-dasharray="3 3" />
      <line x1="30" y1="30" x2="490" y2="30" stroke="#1e293b" stroke-width="1" stroke-dasharray="3 3" />

      
      <text x="10" y="34" fill="#64748b" font-size="9" font-family="sans-serif">10k</text>
      <text x="10" y="84" fill="#64748b" font-size="9" font-family="sans-serif">1k</text>
      <text x="10" y="133" fill="#64748b" font-size="9" font-family="sans-serif">100</text>
      <text x="30" y="145" fill="#64748b" font-size="9" font-family="sans-serif">0 ms</text>
      <text x="88" y="145" fill="#64748b" font-size="9" font-family="sans-serif">42 ms</text>
      <text x="470" y="145" fill="#64748b" font-size="9" font-family="sans-serif">2.4 s</text>

      
      <path id="tailShape" d="M 92 130 C 92 50, 140 25, 170 35 C 220 50, 280 85, 360 110 C 420 125, 475 130, 485 130 Z" fill="url(#reverbTailGrad)" />
      <path id="hfAbsorption" d="M 92 80 C 130 30, 180 35, 230 65 C 280 95, 340 120, 390 130 L 92 130 Z" fill="url(#hfLossGrad)" opacity="0.6" />

      
      <g id="diffusionDots" fill="#bae6fd" opacity="0.65">
        <circle cx="105" cy="115" r="1.5" /><circle cx="115" cy="90" r="1.2" /><circle cx="118" cy="120" r="1.5" />
        <circle cx="130" cy="70" r="1.5" /><circle cx="135" cy="105" r="1.2" /><circle cx="145" cy="50" r="1.5" />
        <circle cx="150" cy="85" r="1.2" /><circle cx="160" cy="118" r="1.5" /><circle cx="170" cy="65" r="1.2" />
        <circle cx="180" cy="95" r="1.5" /><circle cx="195" cy="75" r="1.2" /><circle cx="210" cy="110" r="1.5" />
        <circle cx="230" cy="90" r="1.2" /><circle cx="250" cy="115" r="1.5" /><circle cx="275" cy="100" r="1.2" />
        <circle cx="300" cy="120" r="1.5" /><circle cx="330" cy="112" r="1.2" /><circle cx="370" cy="124" r="1.2" />
      </g>

      
      <rect id="vocalTransient" x="35" y="15" width="10" height="115" rx="3" fill="url(#transientGrad)" />
      <text x="40" y="10" fill="#38bdf8" font-size="9" font-weight="bold" text-anchor="middle">Dry Vocal</text>

      
      <g id="preDelayHighlight">
        <rect x="47" y="20" width="43" height="110" fill="#0284c7" fill-opacity="0.15" stroke="#38bdf8" stroke-dasharray="3 3" stroke-width="1.2" rx="4" />
        <line x1="47" y1="75" x2="90" y2="75" stroke="#38bdf8" stroke-width="1.5" />
        <polygon points="49,72 45,75 49,78" fill="#38bdf8" />
        <polygon points="88,72 92,75 88,78" fill="#38bdf8" />
        <text x="68" y="70" fill="#bae6fd" font-size="9" font-weight="bold" text-anchor="middle">Gap</text>
      </g>

      
      <g id="decayHighlight" opacity="0.3">
        <line x1="92" y1="138" x2="485" y2="138" stroke="#38bdf8" stroke-width="2" />
        <circle cx="92" cy="138" r="3" fill="#38bdf8" />
        <circle cx="485" cy="138" r="3" fill="#38bdf8" />
      </g>

      
      <g id="dampHighlight" opacity="0.3">
        <path d="M 160 38 C 220 50, 260 85, 320 115" fill="none" stroke="#f59e0b" stroke-width="2.5" stroke-dasharray="4 2" />
        <text x="250" y="60" fill="#fcd34d" font-size="9" font-weight="bold">HF Roll-Off</text>
      </g>
    </svg>
  </div>

  
  <div class="focus-bar">
    <span class="focus-text" id="infoText">Pre-Delay: Preserves consonant transients before reverb starts.</span>
    <span class="focus-tag" id="infoTag">Selected</span>
  </div>

  <script>
    const paramDetails = [
      {
        name: "Pre-Delay",
        text: "Pre-Delay: Leaves 42ms space so vocal consonants stay clean.",
        tag: "Clarity",
        activeElem: 'preDelayHighlight'
      },
      {
        name: "Decay Time",
        text: "RT60 (2.4s): Controls size and time for acoustic energy to drop 60dB.",
        tag: "Space",
        activeElem: 'decayHighlight'
      },
      {
        name: "HF Damping",
        text: "HF Damp: Absorbs high frequencies faster to prevent sibilant wash.",
        tag: "Warmth",
        activeElem: 'dampHighlight'
      },
      {
        name: "Diffusion",
        text: "Diffusion (85%): Blends individual echoes into a smooth dense tail.",
        tag: "Density",
        activeElem: 'Texture'
      }
    ];

    let currentParam = 0;

    function selectParam(index) {
      currentParam = index;
      for (let i = 0; i < 4; i++) {
        const knob = document.getElementById('knob-' + i);
        if (i === index) {
          knob.classList.add('active');
        } else {
          knob.classList.remove('active');
        }
      }

      const p = paramDetails[index];
      document.getElementById('infoText').textContent = p.text;
      document.getElementById('infoTag').textContent = p.tag;

      // Visual updates
      document.getElementById('preDelayHighlight').style.opacity = (index === 0) ? '1' : '0.25';
      document.getElementById('decayHighlight').style.opacity = (index === 1) ? '1' : '0.2';
      document.getElementById('dampHighlight').style.opacity = (index === 2) ? '1' : '0.2';
      document.getElementById('diffusionDots').style.opacity = (index === 3) ? '1' : '0.45';
    }

    // Audio preview synthesizer
    function playAudition() {
      const AudioCtx = window.AudioContext || window.webkitAudioContext;
      if (!AudioCtx) return;
      const ctx = new AudioCtx();
      const now = ctx.currentTime;

      // 1. Dry Vocal Transient (Short click / burst)
      const osc = ctx.createOscillator();
      const dryGain = ctx.createGain();
      osc.type = 'triangle';
      osc.frequency.setValueAtTime(440, now);
      osc.frequency.exponentialRampToValueAtTime(110, now + 0.04);
      
      dryGain.gain.setValueAtTime(0.5, now);
      dryGain.gain.exponentialRampToValueAtTime(0.001, now + 0.04);

      osc.connect(dryGain);
      dryGain.connect(ctx.destination);
      osc.start(now);
      osc.stop(now + 0.05);

      // 2. Reverb Tail (Noise Burst delayed by 42ms pre-delay)
      const bufferSize = ctx.sampleRate * 2.4;
      const buffer = ctx.createBuffer(1, bufferSize, ctx.sampleRate);
      const output = buffer.getChannelData(0);
      for (let i = 0; i < bufferSize; i++) {
        output[i] = Math.random() * 2 - 1;
      }

      const whiteNoise = ctx.createBufferSource();
      whiteNoise.buffer = buffer;

      // HF Damping Filter (Lowpass filter sweeping down)
      const filter = ctx.createBiquadFilter();
      filter.type = 'lowpass';
      filter.frequency.setValueAtTime(4500, now + 0.042);
      filter.frequency.exponentialRampToValueAtTime(400, now + 2.4);

      // Reverb Gain Envelope
      const verbGain = ctx.createGain();
      const startVerb = now + 0.042; // 42 ms pre-delay
      verbGain.gain.setValueAtTime(0.0001, now);
      verbGain.gain.setValueAtTime(0.3, startVerb);
      verbGain.gain.exponentialRampToValueAtTime(0.0001, startVerb + 2.0);

      whiteNoise.connect(filter);
      filter.connect(verbGain);
      verbGain.connect(ctx.destination);

      whiteNoise.start(startVerb);
      whiteNoise.stop(startVerb + 2.2);
    }

    // Initialize state
    selectParam(0);
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Pre-Delay Comparison</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    }

    body {
      background: #ffffff;
      color: #1e2945;
      padding: 16px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
    }

    .diagram {
      width: 100%;
      max-width: 620px;
      display: flex;
      flex-direction: column;
      gap: 14px;
    }

    .lane {
      position: relative;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      padding: 12px 14px 8px 14px;
    }

    .lane-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 6px;
    }

    .lane-title {
      font-size: 14px;
      font-weight: 700;
      color: #1e2945;
    }

    .tag {
      font-size: 12px;
      font-weight: 600;
      padding: 2px 8px;
      border-radius: 4px;
    }

    .tag-distant {
      background: #fee2e2;
      color: #b91c1c;
    }

    .tag-clear {
      background: #dcfce7;
      color: #15803d;
    }

    svg {
      width: 100%;
      height: auto;
      display: block;
      overflow: visible;
    }

    .playhead {
      stroke: #0f172a;
      stroke-width: 2;
      stroke-dasharray: 3 3;
      opacity: 0;
      transition: opacity 0.2s;
    }

    .legend {
      display: flex;
      justify-content: center;
      gap: 16px;
      font-size: 12px;
      font-weight: 600;
      color: #64748b;
      margin-top: 2px;
    }

    .legend-item {
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .dot-direct {
      width: 10px;
      height: 10px;
      background: #3b82f6;
      border-radius: 2px;
    }

    .dot-reverb {
      width: 10px;
      height: 10px;
      background: #8b5cf6;
      border-radius: 2px;
    }

    .controls {
      display: flex;
      justify-content: center;
      gap: 10px;
      margin-top: 4px;
    }

    button {
      background: #3b82f6;
      color: #ffffff;
      border: none;
      padding: 8px 16px;
      font-size: 13px;
      font-weight: 600;
      border-radius: 6px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: background 0.2s, opacity 0.2s;
    }

    button:hover {
      background: #2563eb;
    }

    button:active {
      opacity: 0.85;
    }

    .btn-secondary {
      background: #f1f5f9;
      color: #334155;
      border: 1px solid #cbd5e1;
    }

    .btn-secondary:hover {
      background: #e2e8f0;
    }
  </style>
</head>
<body>

  <div class="diagram">
    
    <div class="lane" id="lane0">
      <div class="lane-header">
        <span class="lane-title">0ms Pre-Delay</span>
        <span class="tag tag-distant">Masked / Distant</span>
      </div>
      <svg viewBox="0 0 500 95">
        
        <line x1="30" y1="75" x2="480" y2="75" stroke="#cbd5e1" stroke-width="1.5" />
        <g fill="#94a3b8" font-size="10" text-anchor="middle">
          <text x="30" y="90">0ms</text>
          <text x="142.5" y="90">25ms</text>
          <text x="255" y="90">50ms</text>
          <text x="367.5" y="90">75ms</text>
          <text x="480" y="90">100ms</text>
        </g>
        <g stroke="#e2e8f0" stroke-width="1" stroke-dasharray="2 2">
          <line x1="142.5" y1="10" x2="142.5" y2="75" />
          <line x1="255" y1="10" x2="255" y2="75" />
          <line x1="367.5" y1="10" x2="367.5" y2="75" />
          <line x1="480" y1="10" x2="480" y2="75" />
        </g>

        
        <path d="M 30 75 Q 70 20, 160 55 T 480 75 L 30 75 Z" fill="#8b5cf6" fill-opacity="0.22" />
        
        <line x1="45" y1="75" x2="45" y2="35" stroke="#8b5cf6" stroke-width="2.5" stroke-linecap="round" />
        <line x1="65" y1="75" x2="65" y2="42" stroke="#8b5cf6" stroke-width="2" stroke-linecap="round" />
        <line x1="90" y1="75" x2="90" y2="48" stroke="#8b5cf6" stroke-width="2" stroke-linecap="round" />
        <line x1="120" y1="75" x2="120" y2="56" stroke="#8b5cf6" stroke-width="1.5" stroke-linecap="round" />
        <line x1="155" y1="75" x2="155" y2="62" stroke="#8b5cf6" stroke-width="1.5" stroke-linecap="round" />

        
        <line x1="30" y1="75" x2="30" y2="12" stroke="#3b82f6" stroke-width="4.5" stroke-linecap="round" />

        
        <line id="playhead0" class="playhead" x1="30" y1="5" x2="30" y2="78" />
      </svg>
    </div>

    
    <div class="lane" id="lane40">
      <div class="lane-header">
        <span class="lane-title">40ms Pre-Delay</span>
        <span class="tag tag-clear">Upfront / Clear</span>
      </div>
      <svg viewBox="0 0 500 95">
        
        <line x1="30" y1="75" x2="480" y2="75" stroke="#cbd5e1" stroke-width="1.5" />
        <g fill="#94a3b8" font-size="10" text-anchor="middle">
          <text x="30" y="90">0ms</text>
          <text x="142.5" y="90">25ms</text>
          <text x="255" y="90">50ms</text>
          <text x="367.5" y="90">75ms</text>
          <text x="480" y="90">100ms</text>
        </g>
        <g stroke="#e2e8f0" stroke-width="1" stroke-dasharray="2 2">
          <line x1="142.5" y1="10" x2="142.5" y2="75" />
          <line x1="255" y1="10" x2="255" y2="75" />
          <line x1="367.5" y1="10" x2="367.5" y2="75" />
          <line x1="480" y1="10" x2="480" y2="75" />
        </g>

        
        <rect x="30" y="24" width="180" height="51" fill="#3b82f6" fill-opacity="0.05" />
        <line x1="32" y1="36" x2="208" y2="36" stroke="#3b82f6" stroke-width="1.5" stroke-dasharray="4 2" />
        <text x="120" y="31" fill="#2563eb" font-size="11" font-weight="700" text-anchor="middle">40ms Clean Gap</text>

        
        <path d="M 210 75 Q 250 20, 340 55 T 480 75 L 210 75 Z" fill="#8b5cf6" fill-opacity="0.22" />
        
        <line x1="225" y1="75" x2="225" y2="35" stroke="#8b5cf6" stroke-width="2.5" stroke-linecap="round" />
        <line x1="245" y1="75" x2="245" y2="42" stroke="#8b5cf6" stroke-width="2" stroke-linecap="round" />
        <line x1="270" y1="75" x2="270" y2="48" stroke="#8b5cf6" stroke-width="2" stroke-linecap="round" />
        <line x1="300" y1="75" x2="300" y2="56" stroke="#8b5cf6" stroke-width="1.5" stroke-linecap="round" />
        <line x1="335" y1="75" x2="335" y2="62" stroke="#8b5cf6" stroke-width="1.5" stroke-linecap="round" />

        
        <line x1="30" y1="75" x2="30" y2="12" stroke="#3b82f6" stroke-width="4.5" stroke-linecap="round" />

        
        <line id="playhead40" class="playhead" x1="30" y1="5" x2="30" y2="78" />
      </svg>
    </div>

    
    <div class="legend">
      <div class="legend-item">
        <span class="dot-direct"></span>
        <span>Direct Sound</span>
      </div>
      <div class="legend-item">
        <span class="dot-reverb"></span>
        <span>Reverb Reflections</span>
      </div>
    </div>

    
    <div class="controls">
      <button id="btnPlayAll">▶ Play &amp; Compare 🔊</button>
    </div>
  </div>

  <script>
    let audioCtx = null;

    function getAudioContext() {
      if (!audioCtx) {
        audioCtx = new (window.AudioContext || window.webkitAudioContext)();
      }
      if (audioCtx.state === 'suspended') {
        audioCtx.resume();
      }
      return audioCtx;
    }

    function synthesizeReverb(ctx, startTime, preDelaySec) {
      // Direct sound impulse (transient burst)
      const osc = ctx.createOscillator();
      const oscGain = ctx.createGain();
      osc.type = 'triangle';
      osc.frequency.setValueAtTime(440, startTime);
      osc.frequency.exponentialRampToValueAtTime(110, startTime + 0.04);
      oscGain.gain.setValueAtTime(0.4, startTime);
      oscGain.gain.exponentialRampToValueAtTime(0.001, startTime + 0.04);
      osc.connect(oscGain);
      oscGain.connect(ctx.destination);
      osc.start(startTime);
      osc.stop(startTime + 0.05);

      // Reverb noise tail
      const reverbStart = startTime + preDelaySec;
      const bufferSize = ctx.sampleRate * 0.4;
      const buffer = ctx.createBuffer(1, bufferSize, ctx.sampleRate);
      const data = buffer.getChannelData(0);
      for (let i = 0; i < bufferSize; i++) {
        data[i] = Math.random() * 2 - 1;
      }

      const noise = ctx.createBufferSource();
      noise.buffer = buffer;

      const filter = ctx.createBiquadFilter();
      filter.type = 'lowpass';
      filter.frequency.setValueAtTime(2500, reverbStart);
      filter.frequency.linearRampToValueAtTime(800, reverbStart + 0.4);

      const revGain = ctx.createGain();
      revGain.gain.setValueAtTime(0.18, reverbStart);
      revGain.gain.exponentialRampToValueAtTime(0.001, reverbStart + 0.4);

      noise.connect(filter);
      filter.connect(revGain);
      revGain.connect(ctx.destination);

      noise.start(reverbStart);
      noise.stop(reverbStart + 0.45);
    }

    function animatePlayhead(playheadId, durationMs, callback) {
      const ph = document.getElementById(playheadId);
      ph.style.opacity = '1';
      const startX = 30;
      const endX = 480;
      const startTime = performance.now();

      function step(now) {
        const elapsed = now - startTime;
        const progress = Math.min(elapsed / durationMs, 1);
        const currentX = startX + progress * (endX - startX);
        ph.setAttribute('x1', currentX);
        ph.setAttribute('x2', currentX);

        if (progress < 1) {
          requestAnimationFrame(step);
        } else {
          setTimeout(() => {
            ph.style.opacity = '0';
            ph.setAttribute('x1', startX);
            ph.setAttribute('x2', startX);
            if (callback) callback();
          }, 150);
        }
      }
      requestAnimationFrame(step);
    }

    const btnPlayAll = document.getElementById('btnPlayAll');

    btnPlayAll.addEventListener('click', () => {
      const ctx = getAudioContext();
      btnPlayAll.disabled = true;

      // 1. Play 0ms Pre-Delay
      const t1 = ctx.currentTime + 0.05;
      synthesizeReverb(ctx, t1, 0.0);
      animatePlayhead('playhead0', 800, () => {
        // 2. Play 40ms Pre-Delay after brief pause
        setTimeout(() => {
          const t2 = ctx.currentTime + 0.05;
          synthesizeReverb(ctx, t2, 0.08); // scaled slightly for pedagogical clarity
          animatePlayhead('playhead40', 800, () => {
            btnPlayAll.disabled = false;
          });
        }, 400);
      });
    });
  </script>
</body>
</html>

Early Reflections Versus Late Reverberation Decay in Room Simulation

Mechanical and Acoustic Reverb Systems: Chambers, Plates, and Springs

Digital Reverberation: Algorithmic Synthesis Versus Convolution Impulse Responses

Fine-Tuning High-Frequency Damping, Diffusion, and Density in Mixes

Calculating Pre-Delay Times to Preserve Vocal Intelligibility and Transients

Reverb Equalisation: High-Pass and Low-Pass Filtering for Mix Cleanliness

Non-Linear Reverb: Gated Snare Reverbs and Reverse Ambient Envelopes

arts

Reverb Principles, Types, and Deep Parameter Control

Analogue and Digital Delay Architectures: Tape Loops, BBD Chips, and DSP

Delay Time and LFO Rate Calculations from Tempo (BPM)

Delay Feedback and Regeneration: Managing Decay Cycles and Runaway Oscillation

Slapback Delay: 1950s Rockabilly Echoes and Single-Repeat Doubling

Stereo Ping-Pong Delays and Cross-Feedback Panning Systems

Tape Delay Artefacts: Wow, Flutter, Filtering, and Feedback Saturation

Time-Based Effects Automation: Delay Throws, Feedback Climaxes, and Reverb Swells

Ducked Delays: Sidechain Compression for Dynamic Echo Clearance

Delay Architecture, Echo Parameters, and Rhythmic Time Alignment

music-technology

MUSTECH-10.4

MUSTECH-10.4

Aligned learning resources

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