Īny chemical substance causing functional damage to the inner ear can be defined as an ototoxic agent. Moreover, there is evidence that various chemical products potentially affect hearing, aggravating the harmful effects of noise and even triggering neurotoxic effects. Studies have assessed the effects of occupational noise as a predominant risk for hearing. Such damage may permanently impair hearing thresholds and speech intelligibility, and cause tinnitus and changes in central auditory function. Available from: Įxposure to high noise levels can damage the auditory system, especially the outer hair cells, which are vulnerable to various deleterious stimuli. Effects of Noise and Chemical Exposure on Peripheral and Central Auditory Pathways in Normal-hearing Workers. How to cite this URL: Trabanco JC, Morita B, Matas CG, de Paiva KM, Moreira RR, Sanches SG, Samelli AG. Keywords: Auditory pathways, chemicals, noise, noise-induced hearing loss How to cite this article: Trabanco JC, Morita B, Matas CG, de Paiva KM, Moreira RR, Sanches SG, Samelli AG. It is important that individuals exposed to noise or chemicals have their auditory pathways monitored with complementary assessments. The chemical group did not have significantly different results from those of the control group. Conclusion: These findings suggest that noise exposure produced deleterious effects on the workers’ peripheral and central auditory systems, despite their normal hearing thresholds. There was no difference between the groups in the SSW test, while in PPS, the noise group performed worse than the control group. There were significantly more absences of the inhibitory effect of the efferent system in the noise group. Significantly lower amplitudes were observed in the noise group for otoacoustic emissions. Results: There were no significant differences between the groups in extended high-frequency hearing thresholds. Methods: A total of 54 normal-hearing workers were divided into three groups (chemical, noise, control) and submitted to the following assessments: conventional and extended high-frequency pure-tone audiometry transient and distortion-product otoacoustic emissions, the inhibitory effect of the efferent auditory pathway and Staggered Spondaic Word (SSW) and Pitch Pattern Sequence (PPS) test. Objectives: To assess the effects of noise and chemical exposure on peripheral and central auditory pathways in normal-hearing workers exposed to chemicals or high noise levels and compare the groups with each other and with workers not exposed to either of these agents. Júlio CS Trabanco 1, Bruno Morita 1, Carla Gentile Matas 1, Karina Mary de Paiva 2, Renata R Moreira 3, Seisse GG Sanches 1, Alessandra G Samelli 1ġ Department of Physical Therapy, Speech-language Pathology and Audiology, and Occupational Therapy, Faculty of Medicine (FMUSP), University of São Paulo, Brazil 2 Department of Speech-language Pathology and Audiology, Federal University of Santa Catarina (UFSC), Florianópolis, Brazil 3 Audiological Service, University Hospital, University of São Paulo, Brazil I will focus on the first-order branch of the descending auditory pathway –corticothalamic neurons – and present new evidence showing their sensitivity to motor inputs that precede anticipated sounds.Effects of Noise and Chemical Exposure on Peripheral and Central Auditory Pathways in Normal-hearing Workers I will also discuss the massive descending network of projections that originate in the auditory cortex and innervate nearly every level of subcortical sound processing. Here, I will present new evidence that sluggish temporal processing at the level of the auditory cortex is more than just an inability for fast processing, but instead reflects an emergent specialization for encoding sound features that unfold on very slow time scales. But then what? While sensory coding processes are well understood in the auditory periphery and brainstem, the auditory computations and feature representations that arise de novo at later stages of processing have proven more difficult to discern. Neurons in the auditory brainstem synchronize action potential timing to frequency modulations in excess of 1kHz and compute sub-millisecond discrepancies in the timing of sound waves that reach each ear. To encode these high-speed vibrations, evolutionary pressures designed an exquisite hydro/electro/mechanical force transducer, signal amplifier and frequency analyzer – the Organ of Corti – with sensory cells that can individually encode a 1x1012 range of signal amplitudes at rates up to several kilohertz. Our perception of music, speech and the surrounding soundscape all originate from patterns of vibrations in the cochlea.
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