Auditory fatigue model applications to predict noise induced hearing loss in human and chinchilla

Noise induced hearing loss (NIHL) remains a severe health problem worldwide. Current noise metrics and models have assessment limitations on gradually developing NIHL (GDNIHL). In this study, we apply a complex velocity level (CVL) auditory fatigue model to quantitatively assess the impact of basilar membrane (BM) movement on GDNIHL. The transfer functions of chinchilla and human auditory systems, including the triple-path nonlinear (TRNL) filters to simulate the inner ear responses, are applied to obtain BM velocity distribution. Chinchilla and human experimental hearing loss data are used to validate the proposed CVL model’s effectiveness. The results reveal that the developed CVL model demonstrates high correlations with both chinchilla and human hearing loss data. The linear regression based correlation study indicates the proposed CVL model may accurately predict NIHL in both human and chinchilla

Investigations of Auditory Filters Based Excitation Patterns for Assessment of Noise Induced Hearing Loss

Noise induced hearing loss (NIHL) as one of major avoidable occupational related health issues has been studied for decades. To assess NIHL, the excitation pattern (EP) has been considered as one of mechanisms to estimate movements of basilar membrane (BM) in cochlea. In this study, two auditory filters, dual resonance nonlinear (DRNL) filter and rounded-exponential (ROEX) filter, have been applied to create two EPs, referring as the velocity EP and the loudness EP, respectively. Two noise hazard metrics are also proposed based on the developed EPs to evaluate hazardous levels caused by different types of noise. Moreover, Gaussian noise and pure-tone noise have been simulated to evaluate performances of the developed EPs and noise metrics. The results show that both developed EPs can reflect the responses of BM to different types of noise. For Gaussian noise, there is a frequency shift between the velocity EP and the loudness EP. For pure-tone noise, both EPs can reflect the frequencies of input noise accurately. The results suggest that both EPs can be potentially used for assessment of NIHL

Investigations of Auditory Filters Based Excitation Patterns for Assessment of Noise Induced Hearing Loss

Noise induced hearing loss (NIHL) as one of major avoidable occupational related health issues has been studied for decades. To assess NIHL, the excitation pattern (EP) has been considered as one of mechanisms to estimate movements of basilar membrane (BM) in cochlea. In this study, two auditory filters, dual resonance nonlinear (DRNL) filter and rounded-exponential (ROEX) filter, have been applied to create two EPs, referring as the velocity EP and the loudness EP, respectively. Two noise hazard metrics are also proposed based on the developed EPs to evaluate hazardous levels caused by different types of noise. Moreover, Gaussian noise and pure-tone noise have been simulated to evaluate performances of the developed EPs and noise metrics. The results show that both developed EPs can reflect the responses of BM to different types of noise. For Gaussian noise, there is a frequency shift between the velocity EP and the loudness EP. For pure-tone noise, both EPs can reflect the frequencies of input noise accurately. The results suggest that both EPs can be potentially used for assessment of NIHL

DEVELOPMENT AND VALIDATION OF NEW MODELS AND METRICS FOR THE ASSESSMENTS OF NOISE-INDUCED HEARING LOSS

Noise-induced hearing loss (NIHL) is one of the most common illnesses that is frequently reported in the occupational and military sectors. Hearing loss due to high noise exposure is a major health problem with economic consequences. Industrial and military noise exposures often contain high-level impulsive noise components. The presence of these impulsive noise components complicates the assessment of noise levels for hearing conservation purposes. The current noise guidelines use equal energy hypothesis (EEH) based metrics to evaluate the risk of hearing loss. A number of studies show that the current noise metrics often underestimates the risk of hearing loss in high-level complex noise environments. The overarching goal of this dissertation is to develop advance signal processing based methods for more accurate assessments of the risk of NIHL. For these assessments, various auditory filters that take into account the physiological characteristics of the ear are used. These filters will help to understand the complexity of the ear’s response to high-level complex noises

Comparison of New Metrics for Assessment of Risks of Occupational Noise

Noise induced hearing loss (NIHL) is one of the most common occupational related health problems worldwide. Exposure to excessive noise is the major avoidable cause of permanent hearing loss. The conventional metrics for noise evaluation cannot accurately assess the exposure risks to high-level complex noise, which commonly occurs in many industrial and military fields. Recently, we have developed two advanced models, an adaptive weighting (F-weighting) and a complex velocity level (CVL) auditory fatigue model, to evaluate the risks of occupational noise. In this study, we compared performances of five noise assessment metrics, including F-weighted sound pressure level (SPL) LFeq, CVL model based SPL LCVL, equivalent SPL Leq, A-weighted SPL LAeq, and C-weighted SPL LCeq, using animal experimental data. The animal data includes 22 groups of chinchillas exposed to different types of noise (e.g., Gaussian and non-Gaussian noises). Linear regression analysis is applied to evaluate the correlations between the five noise metrics and the chinchillas’ NIHL data. The results show that both developed F-weighting and CVL models have high corrections with animal hearing loss data compared with the conventional noise metrics (i.e., Leq, LAeq and LCeq). It indicates that both developed models could provide accurate assessment of risks of high-level occupational noise in military and industrial applications. The results also suggest that the CVL model is more accurate than the F-weighting model on assessment of occupational noise

The relationship between tinnitus, cognitive performance and demands on the individual

This Thesis attempted to first replicate the work of Andersson et al. (2000) to identify possible cognitive decrements in tinnitus sufferers. In addition, a number of trait variables were measured in comparison to a matched control group. It was discovered that the tinnitus population did not differ in terms of any trait, yet still performed worse on a number of cognitive tasks - performing as accurately, but significantly more slowly. It was thus concluded that the presence of the tinnitus interfered with cognition by consuming valuable and finite attentional resources.A second study attempted to narrow this down further, identifying specific tasks and specific circumstances in which tinnitus sufferers performed less effectively than their non-tinnitus counterparts.From these results, it was postulated that the relationship between tinnitus severity and cognitive performance is moderated by demand and as such, a longitudinal diary study (six weeks) was undertaken to measure (self-rated) effectiveness under a wide range of demands in real life. Moderated hierarchical regression techniques were thus able to identify situations in which mental demand levels drive the relationship between tinnitus and performance, thus supporting the hypothesis

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 125

This special bibliography lists 323 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1974

Aerospace medicine and biology. A continuing bibliography with indexes, supplement 186

This bibliography lists 159 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in October 1978

Musical hallucinations and their relation with epilepsy

Musical hallucinations are poorly understood phenomena. Their relation with epilepsy was first described over a century ago, but never systematically explored. We, therefore, reviewed the literature, and assessed all descriptions of musical hallucinations attributed to epileptic activity. Our search yielded 191 articles, which together describe 983 unique patients, with 24 detailed descriptions of musical hallucinations related to epilepsy. We also describe six of our own patients. Based on the phenomenological descriptions and neurophysiological data, we distinguish four subgroups of epilepsy-related musical hallucination, comprising auras/ictal, inter-ictal and post-ictal phenomena, and phenomena related to brain stimulation. The case descriptions suggest that musical hallucinations in epilepsy can be conceptualised as lying on a continuum with other auditory hallucinations, including verbal auditory hallucinations, and—notably—tinnitus. To account for the underlying mechanism we propose a Bayesian model involving top-down and bottom-up prediction errors within the auditory network that incorporates findings from EEG and MEG studies. An analysis of phenomenological characteristics, pharmacological triggers, and treatment effects suggests wider ramifications for understanding musical hallucinations. We, therefore, conclude that musical hallucinations in epilepsy open a window to understanding these phenomena in a variety of conditions.Stress and Psychopatholog