An acoustic reflex desensitizes the ear to protect cochlear hair cells

Evidence

The second function of the middle ear is to provide some protection for the hearing system from the effects of loud sounds, whether from external sources or the individual concerned. This occurs as a result of the action of two muscles in the middle ear: the tensor tympani and the stapedius muscle. These muscles contract automatically in response to sounds with levels greater than approximately 75 dB(SPL), and they have the effect of increasing the impedance of the middle ear by stiffening the ossicular chain. This reduces the efficiency with which vibrations are transmitted from the tympanic membrane to the inner ear and thus protects the inner ear to some extent from loud sounds. Approximately 12 to 14 dB of attenuation is provided by this protection mechanism, but this is for frequencies below 1 kHz only. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 541 (#expands, via linked claim)

In both cases, the levels are under your control and so can be reduced. However, there is an effect called the acoustic reflex (see Section 2.1.2), which reduces the sensitivity of your hearing when loud sounds occur. This effect, combined with the effects of temporary threshold shifts, can result in a sound level increase spiral in which there is a tendency to increase the sound level “to hear it better,” which results in further dulling and so on. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 699 (#contradicts, via linked claim)

Categorization

• XREF: connects to: The medial olivocochlear reflex inhibits cochlear compression contralaterally in a graded, output-dependent manner; Middle-ear muscles automatically stiffen to block loud sounds — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 541; The acoustic reflex creates a feedback spiral of ever-increasing volume — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 699 (+5 more)

Related

• Middle-ear muscles automatically stiffen to block loud sounds (similarity 0.90)
• The middle ear both transmits sound and protects against loud noise (similarity 0.90)
• Otosclerosis stiffens ossicle movement and attenuates transmitted sound (similarity 0.89)
• The middle ear amplifies sound pressure through three mechanical mechanisms (similarity 0.89)
• The acoustic reflex creates a feedback spiral of ever-increasing volume (similarity 0.87)
• The acoustic reflex causes a dangerous spiral of turning volume up as hearing dulls (similarity 0.87)
• The ossicle-softer-ligament design protects ears by dumping intense-sound energy. (similarity 0.86)
• The medial olivocochlear reflex inhibits cochlear compression contralaterally in a graded, output-dependent manner (similarity 0.85)
• SOAE bouncing is not caused by middle-ear impedance changes (similarity 0.84)
• Low-frequency sound triggers larger cochlear responses than comparable higher frequencies. (similarity 0.83)
• Outer hair cells respond better than inner hair cells to low-frequency sound (similarity 0.81)
• The cochlea actively amplifies sound and emits echoes that reveal inner-ear health (similarity 0.81)
• Stronger contralateral sound causes greater efferent inhibition and more linear cochlear response (similarity 0.81)
• Ear sensitivity depends jointly on frequency and on sound level (similarity 0.81)
• The ossicles convert air vibrations into mechanical movements that drive cochlear fluid (similarity 0.81)

Broader Connections

• Middle-ear muscles automatically stiffen to block loud sounds #expands (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 541
• The acoustic reflex creates a feedback spiral of ever-increasing volume #contradicts (0.82) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 699
• The medial olivocochlear reflex inhibits cochlear compression contralaterally in a graded, output-dependent manner #complicates (0.80)
• The olivo-cochlear efferent system accelerates recovery from calcium-induced sensitivity changes. #complicates (0.75) — Dijk, Pim van, Physiology, Psychoacoustics and…, 3744