Psychoacoustics

Physics: Equal-loudness contours (ISO 226): 1 phon = threshold at 1 kHz. The ear is most sensitive at 3–4 kHz (ear canal resonance + ossicle resonance), where threshold is ~0 dB SPL. Dynamic range: 0–130 dB SPL. Frequency range: 20 Hz–20 kHz (youth). Tonotopic map: basilar membrane base responds to high frequencies, apex to low. 3000 inner hair cells transduce all hearing. Age-related hearing loss (presbycusis) primarily affects high frequencies (above 4 kHz by age 60).