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If you pan a lead vocal from hard left to dead center without touching the fader, why does it suddenly sound noticeably louder?
When a sound sits in the center of a stereo mix, your digital audio workstation (DAW) sends the exact same signal to both your left and right speakers at the same time.
In the 1930s, stereo pioneer Alan Blumlein realized that playing an identical sound out of two speakers causes acoustic waves to combine in the air, creating a perceived volume boost called acoustic summing.
๐Interactive diagram
To keep the volume feeling perfectly even as you sweep a sound across the stereo field, audio engineers created the pan law.
Also known as a pan rule, a pan law is the attenuation curve applied as a signal moves from hard Left/Right (100% to one channel) toward the phantom centre (50/50 distribution) to preserve perceived volume consistency and mix balance.
Why do different DAWs offer different attenuation values like -3 dB, -4.5 dB, or -6 dB?
The Physics of Summing: Voltage vs. Power
The exact amount of volume gain that happens in the center depends on whether signals combine electrically in a wire or acoustically in a room.
When two identical, coherent audio voltages V combine directly in a mixer circuit or mono sum, their amplitudes add directly: Vtotalโ=V+V=2V
Because voltage gain in decibels uses 20log10โ(VVtotalโโ), doubling the voltage yields an increase of exactly 20log10โ(2)โ+6.02ย dB.
In a real room with reflections and diffuse sound, sound energy combines as acoustic power (P). Adding two equal sound powers (P+P=2P) yields a boost calculated by 10log10โ(2)โ+3.01ย dB.
๐Interactive diagram