Auditory changes in awake guinea pigs exposed to overcompressed music

Area of Science:

• Audiology
• Neuroscience
• Acoustics

Background:

• Loud sound exposure during leisure activities is a global hearing risk factor.
• Current noise safety standards rely on the equal-energy hypothesis, which is insufficient for non-Gaussian sounds.
• Digital audio compression in streaming services alters sound statistics, moving away from Gaussian distributions.

Purpose of the Study:

• To investigate the auditory effects of overcompressed music compared to its original version.
• To assess potential damage to cochlear function and auditory neural pathways.

Main Methods:

• Guinea pigs were exposed to original and overcompressed music (102 dBA, 4 hours).
• Auditory effects were monitored via otoacoustic emissions and middle-ear muscle strength.
• Inner-hair-cell synapse density was measured post-exposure.

Main Results:

• Overcompressed music induced a persistent deficit in middle-ear muscle strength (50% of baseline after 7 days).
• Original music exposure resulted in full recovery of middle-ear muscle strength within 1 day.
• No significant differences in inner-hair-cell synapse density were observed across groups.

Conclusions:

• Dynamic range compression in audio streaming can lead to protracted auditory deficits.
• The observed hearing impairment affects auditory neural pathways, not inner-hair-cell synapses.
• Existing noise exposure regulations may not adequately protect against risks from compressed audio.