AI Tutor
Imagine placing two high-end microphones in front of an acoustic guitar, but the moment you sum the tracks to mono, the low end vanishes and the tone sounds like it is trapped inside a tin can.
This hollow sound is not a broken cable or a bad pre-amp β€” it is the destructive power of acoustic phase interference.

Wave Superposition and Phase

A sound wave consists of alternating cycles of compression (high pressure) and rarefaction (low pressure). Phase measures a wave's progress through its 360∘360^\circ cycle at a specific point in time.
When two identical sound waves combine, their instantaneous amplitudes add together β€” a principle known as acoustic superposition.
When waves align crest-to-crest (0∘0^\circ phase difference), they undergo constructive interference, doubling the signal amplitude (+6 dB).
When waves align crest-to-trough (180∘180^\circ phase difference), they undergo destructive interference, causing complete acoustic cancellation if their amplitudes are equal.
What happens when the delay between two microphones is just a fraction of a millisecond?

Path Difference and Comb Filtering

Sound travels through air at roughly v=343Β m/sv = 343\text{ m/s} (about 1.13Β ft/ms1.13\text{ ft/ms}). If two microphones pick up the same sound source from different distances, the physical difference creates a time delay (Ξ”t\Delta t).
Because different frequencies have different wavelengths (λ=v/f\lambda = v/f), a fixed time delay causes some frequencies to arrive in-phase (0∘0^\circ) and others to arrive out-of-phase (180∘180^\circ).