Application of Quadrature Mirror Filter Banks to simulate the auditory cochlea mechanism of hearing impaired people
Date Issued
2009
Date
2009
Author(s)
Yang, Zhen-Yu
Abstract
Being incapable of perceiving the complete voice contain will lead to hearing impaired people to have learning difficulty on language acquisition.Moreover, normal people without hearing problems may subjectively comprehend the reactions of impaired listeners during communication. Hence, it is difficult for normal people to tackle the core of problems and assist the hearing impaired to overcome communication barriers. We simulate the voice that hearing impaired people might receive by modulating the sampling frequency with use of shifting devices in this study. It could change the sampling frequency using the sampling frequency shifting devices in order to save the computation workload and time when stimulating. Using Analysis Filter Banks of Quadrature Mirror Filter Banks, we divide the voice into several parts of frequency band, or so called subbands. Next, we multiply them with hearing loss gain. Base on the form of hearing incapability and corresponding bandwidth, and then combine several voice signals subbands with Synthesis Filter Banks of Quadrature Mirror Filter Banks to form one united output signal. In this study, tree-structured Quadrature Mirror Filter Banks and Cosine Modulated Filter Banks are applied to divide natural sound into 32 frequency band of equal same bandwidth. Our work is to stimulate four types of hearing loss, which are 40dB uniform hearing loss, mild low-frequency hearing loss, moderate high-frequency hearing loss, and severe high-frequency hearing loss. Since the signal is nonlinearly producing, combination of several subbands of uniform filter banks is capable of produce non-uniform filter banks with 1/3 one-third-octave approximation. Using three approaches above, we stimulate what is actually perceived by the impaired listeners. Our intention is to imitate the hearing impairment model, and let the public, especially special educators, understand the reactions that hearing impaired individuals make when speaking. More effectively, we can assist them to overcome obstacles in language development when in study. Therefore, man with the loss of hearing is not restricted or isolated from his or her daily lives and normal social activity.
Subjects
Quadrature Mirror Filter Banks
Analysis Filter Banks
Synthesis Filter Banks
Cosine Modulated Filter Banks
One-third Octave
non-uniform filter banks
Type
thesis
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