Auditory fatigue

Usually, minor bending of the stereocilia of the inner ear is associated with temporary hearing loss and is involved in auditory fatigue.

[2] The TTS that is experienced is the exhaustion of the active system located at the locus of the traveling wave driven by the cochlear amplifier described below.

[4] As the stimulation increases, it is assumed that basilar membrane displacement, caused by the traveling wave, becomes continually more basal in regards to the cochlea.

Currently it is believed that auditory fatigue and NIHL are related to excessive vibrations of the inner ear which may cause structural damages.

[6][7][8] Metabolic activity is required in order to maintain the electrochemical gradients used in mechano-electrical and electro-mechanical transduction during noise exposure and sound recognition.

[6][11] In all cases of auditory fatigue, sufficient recovery time should allow full correction of the hearing impairment and return threshold levels to their baseline values.

[2] There is currently no way to estimate the amount of time needed to recover from auditory fatigue because it is not usually detectable until after the injury has already occurred.

Research has been done to determine their ability to protect against auditory fatigue and permanent damage through toughening phenomena, a state described by reduced active cochlear displacements.

Although limited research has been done with these two substances in terms of protective drug regimes because of their associated risks, both have shown positive results in reducing auditory fatigue by the decrease in ROS formation through individual mechanisms described below.

This reduction in active displacement is again associated with depression of the cochlear amplifier which decreases the excessive vibrations experienced during noise-exposure.

[21] In addition, NAC, or N-acetyl-L-cysteine (acetylcysteine), has been shown to reduce ROS formation associated with the excessive vibrations induced by the noise exposure.

[10][22][23] Although auditory fatigue and NIHL protective measures would be helpful for those who are constantly exposed to long and loud noises, current research is limited due to the negative associations with the substances.

[27] In this case, the auditory system undergoes temporary changes caused by a decrease in the oxygen tension of the cochlear endolymph that leads to vasoconstriction of the local vessels.

Exposure to noise greater than 95 dB in individuals with heavy workloads was shown to cause severe TTS.

[12] In addition, the workload was a driving factor in the amount of recovery time required to return threshold levels to their baselines.

Contact with ototoxic chemicals such as styrene, toluene and carbon disulfide heighten the risk of auditory damages.

[12] Those individuals in work environments are more likely to experience the noise and chemical combination that can increase the likelihood of auditory fatigue.

[10] Also, the combined effects of these chemicals and the noise produce greater auditory fatigue than when an individual is exposed to one factor immediately followed by the next.