Frequency responses of hearing aids and their effects on the speech perception of eight hard-of-hearing subjects

This dissertation examines the relationship between frequency response and word-discrimination performance of hearing-impaired persons. Three questions are addressed: does the restoration of the normal field-to-eardrum transfer function improve word discrimination; is the restoration of the normal shape of the audibility curve (uniform hearing level at all frequencies) beneficial to hearing-impaired listeners; and can speech discrimination be improved by an extension of the present narrow-band response in hearing aids.

Evaluation of sentence perception of adults with hearing loss when using a video teleconferencing system

This study evaluate the speech perception of hearing-impaired adults (with varying degrees of deafness) when using a video teleconferencing system (an integrated service digital network).

Speech perception by the chinchilla: discrimination of /I/ and /A/ in various consonantal contexts

This paper discusses a study done with chinchillas and their ability to organize speech sounds into auditory concepts.

Dimensional tradeoffs in the perception of complex tone sequences

This paper reviews a study of four complex tones and sound perception among the tones.

Perception and cognition in deaf children

This dissertation examines conceptual functioning of hearing impaired persons. Specifically the study addresses perceptual and conceptual functioning in both deaf and hearing children and whether there is a difference in performance as a function of hearing status, as attributable to age differences, or as a function of the school environment.

Perception of speech through a 500 Hz low-pass filter: sensory aids and communication strategies

This paper reviews a study to investigate how a hearing impaired person can learn to discriminate speech distorted by a low pass filter in a sensory aid.

The effect of talker age and gender on speech perception of pediatric cochlear implant users

Most clinically-employed speech materials for testing hearing impaired individuals are recordings made by adult male talkers. The author examined the possible effect of talker age and gender on the speech perception of children through the use of 1) two speech perception tests, each with four talker types (adult males, adult females, 10-12 year olds, 5-7 year olds), and 2) two groups of pediatric listeners: normal-hearing (NH) and cochlear implant users (CI).

Student musicians' perception of loudness and how it correlates to the measured level

The purpose of this project was to evaluate student musicians’ perception of loudness and see how it relates to the measured sound level when playing an instrument alone and when playing in an orchestra. Perhaps by examining this relationship, strategies can be developed to educate musicians on the risk of excessive noise exposure and hearing protection options.

Evaluation of auditory-visual speech perception in individuals diagnosed with dementia of the Alzheimer's type

Auditory-visual speech perception testing was completed using wordandconsonant-level stimuli in individuals with known degrees of dementia of theAlzheimer’s type. The correlations with the cognitive measures and the speechperception measures (A-only, V-only, AV, VE or AE) did not reveal significantrelationships.

The effect of talker age and gender on speech perception of pediatric hearing aid users

Even though pediatric hearing aid (HA) users listen most often to female talkers, clinically-used speech tests primarily consist of adult male talkers' speech. Potential effects of age and/or gender of the talker on speech perception of pediatric HA users were examined using two speech tests, hVd-vowel identification and CNC word recognition, and using speech materials spoken by four talker types (adult males, adult females, 10-12 year old girls, and 5-7 year old girls). For the nine pediatric HA users tested, word scores for the male talker's speech were higher than those for the female talkers, indicating that talker type can affect word recognition scores and that clinical tests may over-estimate everyday speech communication abilities of pediatric HA users.

Biodegradation of the herbicide mecoprop-p with soil depth and its relationship with class III tfdA genes

Mecoprop-p [(R)-2-(4-chloro-2-methylphenoxy) propanoic acid) is widely used in agriculture and poses an environmental concern because of its susceptibility to leach from soil to water. We investigated the effect of soil depth on mecoprop-p biodegradation and its relationship with the number and diversity of tfdA related genes, which are the most widely known genes involved in degradation of the phenoxyalkanoic acid group of herbicides by bacteria. Mecoprop-p half-life (DT50) was approximately 12 days in soil sampled from <30 cm depth, and increased progressively with soil depth, reaching over 84 days at 70–80 cm. In sub-soil there was a lag period of between 23 and 34 days prior to a phase of rapid degradation. No lag phase occurred in top-soil samples prior to the onset of degradation. The maximum degradation rate was the same in top-soil and sub-soil samples. Although diverse tfdAα and tfdA genes were present prior to mecoprop-p degradation, real time PCR revealed that degradation was associated with proliferation of tfdA genes. The number of tfdA genes and the most probable number of mecoprop-p degrading organisms in soil prior to mecoprop-p addition were below the limit of quantification and detection respectively. Melting curves from the real time PCR analysis showed that prior to mecoprop-p degradation both class I and class III tfdA genes were present in top- and sub-soil samples. However at all soil depths only tfdA class III genes proliferated during degradation. Denaturing gradient gel electrophoresis confirmed that class III tfdA genes were associated with mecoprop-p degradation. Degradation was not associated with the induction of novel tfdA genes in top- or sub-soil samples, and there were no apparent differences in tfdA gene diversity with soil depth prior to or following degradation.