What is the relationship between sound wave amplitude and perceived loudness?

What is the relationship between sound wave amplitude and perceived loudness?

• A. Amplitude is inversely proportional to perceived loudness.
• B. Amplitude has no relation to perceived loudness.
• C. Amplitude is proportional to perceived loudness.
• D. Perceived loudness determines amplitude.

Answer: (C)

The main idea is that the strength of the physical signal, represented by amplitude, directly drives how loudly we perceive a sound. When the pressure fluctuations of a sound wave are larger (greater amplitude), the eardrum experiences bigger moves, which leads to greater deflection of the hair cell stereocilia. This causes larger receptor potentials in the inner hair cells and more neurotransmitter release onto auditory nerve fibers, resulting in higher neural firing rates along the auditory pathway. That stronger neural signaling is what we perceive as louder sound. So, within the typical listening range, increasing amplitude leads to a louder percept, making amplitude proportional to perceived loudness. It’s useful to remember that loudness isn’t a perfect linear measure of amplitude or intensity—our perception grows more logarithmically with actual energy—but the essential relationship reflected in the option is correct. The other ideas—loudness increasing while amplitude decreases, or loudness dictating amplitude—don’t fit with how the auditory system converts physical signal strength into a percept.

The main idea is that the strength of the physical signal, represented by amplitude, directly drives how loudly we perceive a sound. When the pressure fluctuations of a sound wave are larger (greater amplitude), the eardrum experiences bigger moves, which leads to greater deflection of the hair cell stereocilia. This causes larger receptor potentials in the inner hair cells and more neurotransmitter release onto auditory nerve fibers, resulting in higher neural firing rates along the auditory pathway. That stronger neural signaling is what we perceive as louder sound. So, within the typical listening range, increasing amplitude leads to a louder percept, making amplitude proportional to perceived loudness.

It’s useful to remember that loudness isn’t a perfect linear measure of amplitude or intensity—our perception grows more logarithmically with actual energy—but the essential relationship reflected in the option is correct. The other ideas—loudness increasing while amplitude decreases, or loudness dictating amplitude—don’t fit with how the auditory system converts physical signal strength into a percept.