The voice in the shower

Problem

In the shower one’s own voice sounds fuller and deeper. Why? Does the same mechanism explain why an acoustic guitar is louder than the string off its body?

Solution

Acoustic resonance of the enclosure. The small shower cubicle, with hard, reflective walls, behaves like a resonant cavity: it supports standing waves at certain natural frequencies (resonance modes). The components of the voice close to these modes are selectively amplified, especially the low and mid harmonics. The result is a voice that sounds fuller and deeper. Repeated reflections (reverberation), which lengthen the sound, also contribute.

Same mechanism in the guitar. Yes, broadly speaking it is the same principle of resonant coupling. The string alone moves very little air and is almost inaudible. The soundbox (with its internal air and sound hole) vibrates in accord with the string and sets a much larger area of air in motion, radiating far more acoustic energy: this is why a guitar with a body is enormously louder than the bare taut string.

$\ev{\text{The narrow enclosure resonates in the vocal bands and selectively amplifies frequencies near its modes (like the guitar's body).}}$

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Topics: Onde Concepts: Onde stazionarie Skills: Analisi di casi limite e fantafisica