Cochlear Synaptopathy Following Noise Exposure in Guinea Pigs: Its Electrophysiological and Histological Assessments

Exposure to high level of noise,may cause the permanent cochlear synaptic degeneration.In present study,a model of noise induced cochlear synaptopathy was established and the electrophysiological and histological metrics for its assessment was designed.6 guinea pigs were subjected to a synaptopathic noise(octave band of 4 kHz at 104 dB SPL,for 2-h).The amplitude growth curve of Auditory Brainstem Response(ABR)wave-I and wave-III latency shift in presence of noise were calculated.These indexes were considered in pre-exposure,1 day post exposure(1DPE),1 week post exposure(1WPE)and 1 month post exposure(1MPE)to noise.Finally,the samples were histologically analyzed.ABR wave-I amplitude was different between pre and 1DPE(p-value≤0.05).However,at 1WPE,it was recovered at low intensities but at 70 dB SPL and above,the differences persisted even till 1MPE.In masked ABR,the latency shift of wave-III was different between pre and 3 post exposure assessments(p-value≤0.05).Electro-microscopic analysis confirmed the synaptic degeneration,as the ribbons were larger than normal,hollow inside,and spherical and irregular in shape,also,the post synaptic density was abnormally thick and missed its flat orientation.These data revealed that noise at level below that can produce permanent hearing loss,can incur synaptic injury.So,noise is considered to be more damaging than previously thought.Accordingly,designing tools for clinical assessment of synaptopathy is beneficial in comprehensive auditory evaluation of those with history of noise exposure and also in hearing protection planning.

Application of the BASNEF Model in Safety Training in Automobile Manufacturing Plants

After controls,including engineering and management,thefinal way to control noise is to use hearing protection devices.Duetothelack ofastandardized questionnaireregarding investigatingworkers’use of hearing protection devices on the basis of the BASNEF behavioral model,the present study was conducted to investigate the effect of health education based on the BASNEF model on the use of hearing protection devices in workers of an auto-mobile manufacturing plant in Iran.This quasi-experimental and prospective intervention study was performed on 80 workers at an automobile manufacturing plant who are exposed to noise levels above 85 decibels and donot use hearing protection devices.In this study,40 people working in a cast iron foundry were selected as the inter-vention group,and 40 working in aluminum casting were chosen as the control group.Questionnaires were ana-lyzed at the beginning of the intervention and three months after the intervention in the intervention and control groups.There was no significant difference between the intervention and control groups before the intervention.There was a significant difference between the intervention and control groups after the intervention in the area of knowledge.A significant correlation was observed between the intervention and control groups after the inter-vention program in all areas of the BASNEF educational model except behavioral intention.In this study,the effect of educational intervention on the use of hearing protection devices was investigated,and with the educa-tional intervention,it was tried to get help from influential people and enabling factors in education based on the BASNEF model.The results showed that the educational intervention based on the BASNEF model can improve the knowledge of individuals in both the intervention and control groups.

Noise Exposure and Its Auditory Effect on Industrial Workers

This paper analyzes the effect of exposure to noise among industrial workers in Nigeria to discover the level of exposure to noise that causes auditory defects or noise-induced hearing loss (NIHL), this paper primarily covers the evaluation of hearing impairment and its severity on exposure to loud sounds (acoustic trauma) and the role of hearing protective devices for industrial workers for prevention of Noise Induced Hearing Loss (NIHL). The paper also discusses the findings and guides as preventive methods for such industries. A total sample of seventy (70) workers were selected from three (3) manufacturing industries for this study. This study revealed a statistically significant difference in the hearing threshold within the selected industries over the selected period of time relating to the theory of excessive noise present in a given environment tends to affect people or in this case study employees hearing if proper hearing protection isn’t used for prolonged hours or time, the study also surveys the various effect of noise on human health including various steps of noise control in such settings.