Hearing damage first appears at the ear canal’s resonance frequency near 4 kHz

Evidence

Because the damage is caused by excessive noise exposure, it is more likely at the frequencies at which the acoustic level at the ear is enhanced. The ear is most sensitive at the first resonance of the ear canal, or about 4 kHz, and this is the frequency at which most hearing damage first shows up. Hearing damage in this region is usually referred to as an “audiometric notch” because of its distinctive shape on an audiogram (once the results have been plotted following a hearing test); see Figure 2.21. (Hearing testing using audiograms and the dBHL scale are described in detail in Section 7.2.) This distinctive pattern is evidence that the hearing loss measured is due to noise exposure rather than to some other condition, such as the inevitable high-frequency loss due to aging. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 677

Because the damage is caused by excessive noise exposure, it is more likely at the frequencies at which the acoustic level at the ear is enhanced. The ear is most sensitive at the first resonance of the ear canal, or about 4 kHz, and this is the frequency at which most hearing damage first shows up. Hearing damage in this region is usually referred to as an “audiometric notch” because of its distinctive shape on an audiogram (once the results have been plotted following a hearing test); see Figure 2. — David Howard, Jamie Angus, coustics and Psychoacoustics, 667

Categorization

• DEFINE: Defines the audiometric notch as the diagnostic signature distinguishing noise damage from age-related hearing loss.
• corroborated: 3 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 677; David Howard, Jamie Angus, coustics and Psychoacoustics, 667
• XREF: connects to: Normal hearing is most sensitive near 2 to 5 kHz — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 168; Outer ear canal resonance explains peak sensitivity near 4 kHz — Eric J. Heller, Why You Hear What You Hear- An…, 2005; The ear canal acts as a quarter-wavelength resonator amplifying 3-4 kHz by 10 dB — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 728 (+3 more)

Broader Connections

• Middle ear impedance match is optimal near 1 kHz #corroborates (0.72)
• Repeated loud exposures convert temporary hearing loss into permanent damage #expands (0.72) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1876