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Hearing, Sound, Noise, and Vibration
Published in R. S. Bridger, Introduction to Human Factors and Ergonomics, 2017
Audiometric testing determines the minimum intensity (the threshold) at which a person can detect sound at a particular frequency. Since sensitivity to particular frequencies is lost due to age or damage, the threshold increases. It is in this sense that hearing loss can be described as a threshold shift. Temporary threshold shifts can occur after exposure to loud noise (e.g., in clubs). The sensory cells in the cochlea remain intact but the acute loss of afferent nerve function and delayed regeneration of the cochlear nerve can cause progressive loss of hearing which is not, initially, detected by conventional hearing tests (Kujawa and Liberman, 2009). Repeated exposure leads to permanent threshold shifts (noise-induced deafness). Figure 11.5 shows example audiograms of noise-induced threshold shifts.
Bidirectional Neural Interfaces
Published in Chang S. Nam, Anton Nijholt, Fabien Lotte, Brain–Computer Interfaces Handbook, 2018
Mikhail A. Lebedev, Alexei Ossadtchi
A variety of artificial sensations have been developed using afferent NIs, and many more systems will likely be developed in the future. Cochlear implant is undoubtedly the most successful story of an afferent NI, with hundreds of thousands of people restoring hearing using this type of neural prosthesis (Shannon 2012; Wilson & Dorman 2008). This implant evokes auditory sensations by applying electrical pulses to the cochlear nerve. Implanted patients can recognize speech, different voices, and even music.
Soft Tissue Replacements
Published in Joyce Y. Wong, Joseph D. Bronzino, Biomaterials, 2007
K.B. Chandran, K.J.L. Burg, S.W. Shalaby
Artificial ear implants capable of processing speech have been developed with electrodes to stimulate cochlear nerve cells. Cochlear implants also have a speech processor that transforms sound waves into electrical impulses that can be conducted through coupled external and internal coils. The electrical impulses can be transmitted directly by means of a percutaneous device.
Degenerate brainstem circuitry after combined physiochemical exposure to jet fuel and noise
Published in Journal of Toxicology and Environmental Health, Part A, 2022
O’neil W. Guthrie, Brian A. Wong, Shawn M. McInturf, David R. Mattie
The noise exposure apparatus and procedure were reported in detail (Fechter et al. 2012; Guthrie et al. 2014, 2016). Briefly, animals were exposed to 85 dB SPL of noise for 6 hr per day, 5 days per week for 4 weeks. White noise was high-pass filtered with a 48 dB/octave roll-off to produce a 5.6–11.3 kHz band pass noise. During the procedure, the sound intensity was monitored inside the chamber using a Spectral Dynamics Puma data acquisition system (Spectral Dynamics, San Jose, CA) to ensure the target level was met. The animals were conscious during the entire procedure. This specific exposure paradigm was selected because it does not affect the sensory end-organ (cochlea) or PNS (cochlear nerve) of LE rats (Guthrie et al. 2015, 2014).