Simulation-based study of human auditory response characteristics and development of a prototype for advanced noise guideline are two major focuses of this dissertation research. This research was conducted as a part of the long-term effort to develop an improved noise guideline for better protection of the workers exposed to various noise environments.
The human auditory responses were studied with simulation models. A human full-ear model derived from an existing model, Auditory Hazard Assessment Algorithm for Human (AHAAH), was utilized as a baseline for the study. Frequency- and time-domain responses of well-known human middle ear network models were cross-compared to estimate expected accuracy of the models and understand their proper use. Responses of the stapes to impulsive noises were investigated by using the middle ear models to understand the effects of the temporal characteristics of impulsive noises on the responses. Available measured transfer functions between the free-field pressure and the stapes response for human and chinchilla were also used to study the auditory response characteristics. The measured transfer functions were refined and reconditioned to make them have equivalent formats. Using the reconstructed transfer functions, time-domain stapes responses of human and chinchilla to impulsive and complex type noises were calculated and compared. Applicability of the noise metrics defined in terms of the stapes response to assess the risk of the noise induced hearing loss was studied.
A prototype of an improved noise guideline was developed from existing chinchilla noise exposure data. Applying a new signal processing technique to the time histories of the exposed noises and studying the relationship between the noise metric and the permanent threshold shift (PTS), the dose-response relationship (DRR) was established in a compatible way with the definition used in current human noise guidelines. From the DDR, noise induced hearing loss (NIHL) threshold is estimated as a function of frequency. An advanced noise guideline that enables quantitative, frequency by frequency assessment of risk of the noise was developed by utilizing the identified NIHL threshold. The guideline was developed so that it can be easily transformed to a human noise guideline. Therefore, the guideline serves as a prototype of a future human noise guideline.
|Commitee:||Lim, Teik, Murphy, William, Schulz, Mark|
|School:||University of Cincinnati|
|School Location:||United States -- Ohio|
|Source:||DAI-B 71/04, Dissertation Abstracts International|
|Subjects:||Audiology, Occupational health, Mechanical engineering|
|Keywords:||Auditory system, Network model, Noise-induced hearing loss, Transfer function model|
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