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Communication: Language and Speech
Published in Frank H Hawkins, Harry W Orlady, Human Factors in Flight, 2017
Frank H Hawkins, Harry W Orlady
While the vocal system generates speech, it is the auditory system which senses it and conveys vocal communication to the brain. As this mechanism is of vital importance in ensuring the effectivity of the communication, we should look at it more closely (Fig. 7.3). The external ear leads via an auditory canal to the tympanic membrane, or eardrum. The variations of pressure in the air cause this tightly stretched membrane to vibrate. Attached to this membrane, in the middle ear, are three tiny bones or ossicles called the hammer (malleus), the anvil (incus) and the stirrup (stapes). These bones are attached to the oval window of the inner ear, where a diaphragm sets in motion the fluid inside the cochlea. Within the cochlea is the Organ of Corti, a complex structure which contains the auditory nerve ends and the hair cells. The various components in this system can be seen as transformers and amplifiers.
O
Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[acoustics, biomedical, electronics, general] Auditory element in the cochlea of the inner ear. The cochlea has a spiral shape, resembling a snail shell. The organ of Corti is found on the scala-media side on the basilar membrane. The Organ of Corti derived its name from the pathologist Marquis Alfonso Giacomo Gaspare Corti (1822–1876) from Italy who described it. The receptor aspect of the organ of Corti has two types of receptor cells: the inner hair cell and the outer hair cell. Each of these hair cells have different functions. The organ of Corti contains two rows of rod cells, arranged on the membrane in the form of a minute arch. To the arch, four rows of hair cells are fixed, consisting of one row on the inner side and three on the outer side. The function of the Organ of Corti is the conversion of sound vibrations into nerve pulses. The sound waves are transmitted along the cochlear duct, which form a longitudinal wave that results in the displacement of the tips of the hair, and as such flexing the hair which in turn generates an action-potential. These action-potential impulses are transmitted by the auditory nerve, or cochlear nerve, to the brain, at which location they are interpreted as sound with the frequency associated with the location on the basilar membrane. The detection of long wavelengths are farther into the cochlea (toward the apex), whereas the high frequency are detected close to the entry point at the oval membrane (the base) (see Figure O.39).
Environmental Health
Published in Lorris G. Cockerham, Barbara S. Shane, Basic Environmental Toxicology, 2019
Camille J. George, William J. George
Hearing loss results in damage (as in temporary hearing loss) or loss of receptor hair cells in the Organ of Corti. These hair cells are located throughout the cochlea of the inner ear and detect vibrations in the fluid of the inner ear. Loud noises can damage or even destroy these hair cells. Repeated exposure to noise levels between 70 and 85 dB has been shown to produce hearing loss (U.S. EPA, 1978). This type of hearing loss associated with extensive noise exposure is referred to as sociocusis. Natural death of the hair cells occurs with aging. This is termed presbycusis and usually begins with the loss of the higher frequency receiving hair cells located nearest the round window.
Obstructive sleep apnea risk and hearing impairment among occupational noise-exposed male workers
Published in Archives of Environmental & Occupational Health, 2023
Seunghyeon Cho, Won-Ju Park, Ji-Sung Ahn, Dae-Young Lim, Su-Hwan Kim, Jai-Dong Moon
Previous studies have been conducted to examine the association of OSA and hearing impairment primarily in patients who visited a hospital with snoring, sleep apnea, or sleep disorder.6,7,13–18 These studies have suggested that OSA, especially severe OSA, is associated with hearing impairment. In a study by Chopra et al., increased OSA severity was associated with hearing loss at both high and low frequencies in Hispanic population.6 Similarly, in our study, the hearing thresholds of the high-risk OSA group at a frequency of 1, 2, 3 and 4 kHz in each ear were higher than those of the low-risk OSA group. The high OSA risk elevated the risk of hearing impairment in all models. However, in the analysis performed by reclassifying hearing impairment into high- and low-frequency, high-risk OSA group showed a significant association only with high-frequency hearing impairment compared with the low-risk OSA group. These results are consistent with those of studies reporting hearing loss only at higher frequencies.13,14 It is also consistent with the results of a study by Yu Li et al. that evaluated OSA using STOP-Bang questionnaire in middle-aged men.45 This can be explained by the following. Inner and outer hair cells of the organ of Corti respond to sound frequencies according to their tonotopic arrangement; high-frequency sounds localize to the base of the cochlea. The base of the organ of Corti is supplied by end arterioles without anastomoses, and thus, it may be more vulnerable to hypoxemia and fluctuations in oxygen than areas of the retina remote from the fovea centralis.46,47