The P300 complex has been dissociated into a parietally maximal P3b and a more anteriorly distributed P3a in auditory, visual and somatosensory modalities. The seven experiments reported in this thesis investigate the variables affecting the elicitation of the P3a. The Knight et al. (1989) paradigm was used which involves the presentation of frequent, rare target and rare nontarget auditory stimuli. Experiment 1 showed that the P3a was elicited by novel sounds (environmental noises) when presented as rare nontargets in a sequence of frequent and target tones. When the rare nontarget novel sounds were presented in a sequence of other novel sounds the P3a was not elicited (Experiment 2). Experiment 3 showed that making the rare novel sound a target abolished the P3a, as did omitting the frequent stimuli from the sequence (Experiment 4). In the experiments in which the P3a was abolished, the novel sounds were found to elicit a P300 deflection with a parietally maximal scalp distribution (P3b). Other experiments showed no indication of habituation of the P3a over subsequent stimulus presentations (experiment 6) but did show that the amplitude of the P3a was larger when preceded by several stimuli different to the eliciting novel sound, than when immediately preceded by the identical sound (experiment 7). In contrast to novel sounds, tones did not elicit a P3a, even when presented as rare nontargets among frequent and target novel sounds (experiment 5). The findings were related to a recent model of auditory attention (Naatanen, 1990). The P3a was interpreted as reflecting a process related to the orienting of attention resulting from the detection of a mismatch between present and previous stimuli.

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Ninety college Ss were first classically "conditioned" to color names and subsequently transferred to a dichotic listening task requiring shadowing of a five-minute prose passage. Embedded in the non-attended channel were previously shock-associated color words. In one condition (same pitch) both the shadowed and non-attended material was read by the same speaker. In the second condition (different pitch) the shadowed and non-attended channels were read by different speakers. Within conditions right/left ear of presentation of shadowing was factorially arranged. The dependent measure was phasic skin resistance changes in the non-attended channel to previously shock-associated stimuli. Autonomic responding was not affected by pitch characteristics. Ear of presentation showed a strong effect; autonomic responding to non-attended stimuli was enhanced by left ear presentation. The interaction of pitch by ear of presentation was significant; a left ear advantage was favored in the same pitch condition. Shadowing efficiency was not impaired at the time of responding to non-attended material nor was shadowing performance altered by pitch distinctions or ear of presentation. The above findings are discussed in terms of the Deutsch and Deutsch and Treisman theories of selective attention. / Arts, Faculty of / Psychology, Department of / Graduate

In order for an aircraft to remain in stable flight, the center of gravity (CG) of an aircraft must be located in front of the center of lift (CL). As the center of gravity moves rearward, pitch stability decreases and the sensitivity to control input increases. This increase in sensitivity is known as pitch gain variance. Minimizing the pitch gain variance results in an aircraft with consistent handling characteristics across a broad range of center of gravity locations. This thesis focuses on the development and testing of an open loop computer simulation model and a closed loop control system to minimize pitch axis gain variation as center of gravity changes. DATCOM and MatLab are used to generate the open loop aircraft flight model; then a closed loop PD (proportional-derivate) controller is designed based on Ziegler-Nichols closed loop tuning methods. Computer simulation results show that the open loop control system exhibited unacceptable pitch gain variance, and that the closed loop control system not only minimizes gain variance, but also stabilizes the aircraft in all test cases. The controller is also implemented in a Scorpio Miss 2 radio controlled aircraft using an onboard microprocessor. Flight testing shows that performance is satisfactory.

<p> Experiments have shown that manipulations of vocal fundamental frequency, a physical correlate of voice pitch, alter perceptions of vocal attractiveness. Individual experiments, however, have found different effects of pitch manipulations on attractiveness. One possible explanation for the disparate findings may be differences in the strength of pitch manipulations used between studies. The focus of this thesis is to determine psychophysical properties of vocal attractiveness based on pitch manipulations. Within the thesis, two experiments are described that were designed to find just-noticeable differences in vocal attractiveness based on pitch manipulations. The experiments were also designed to determine if there are limits for voice pitch preferences. Relevant background concepts to the thesis are described in Chapters 2-5, and a manuscript is presented in Chapter 6 that describes the methods and results of the experiment, and gives a discussion of the findings.</p> <p> In Chapter 2, the basic anatomy underlying vocal production is explained, including the anatomical structures involved in the source-filter model of vocal production.</p> <p> In Chapter 3, relevant acoustic properties of the voice are described, including fundamental frequency, harmonics, and formant frequencies.</p> <p> In Chapter 4, the basic anatomy involved in audition is explained, including how sound is propagated through the ear.</p> <p> In Chapter 5, a brief review of previous psychophysical research on pitch discrimination and perceived vocal traits is given.</p> <p> In Chapter 6, two experiments are described. Experiment 1 was designed to determine just-noticeable differences in voice pitch discrimination. Experiment 2 was designed to determine just-noticeable differences in voice attractiveness based on manipulations of voice pitch. Experiment 2 was also designed to assess potential limits to voice pitch preferences for supernormal stimuli. Just-noticeable differences in vocal attractiveness were larger than just-noticeable differences in pitch discrimination. Just-noticeable differences in attractiveness were larger in women's voices than men's. There was no limit in men's preferences for highpitched voices, however there was a limit for women's preferences for low-pitched voices below the natural male pitch range.</p> / Thesis / Master of Science (MSc)

The focus of this thesis is to investigate the role of voice pitch (the perception of fundamental frequency and/or corresponding harmonics) and apparent vocal tract length (VTL-the perception of the vocal tract resonances i.e. formant frequencies) in perceptions of trustworthiness and other related social attributions. Past research has found that women trust men with relatively higher pitched voices as long-term romantic partners. People with relatively higher pitched voices are also judged as more cooperative than people with relatively lower pitched voices. However, women choose men with relatively lower pitched voices when asked to select which leaders are more trustworthy and make better economic decisions. In study 1, I used “The Trust Game” to determine whether women trust men with higher or lower pitched voices to evenly divide a sum of money. Women trusted men with relatively higher pitched voices more often. Thus, even though men with lower pitched voices are more often elected to office, and are CEOs of larger companies that make more money, women trust men with relatively low pitched voices less than men with relatively high pitched voices to equitably distribute money. Surprisingly, no studies have examined the relationship between VTL and trust, but one recent study examined the relationship between VTL and perceptions of cooperation. In study 2, I was the first to test the role of voice pitch and VTL on perceptions of trust and cooperation. In general, people with higher frequency voices (high pitch and a shorter VTL) were relatively more cooperative and trustworthy than people with lower frequency voices (low pitch and a longer VTL). Despite correlations between the effects of voice frequency manipulations on ratings of trustworthiness and cooperativeness, the amount to which people thought pitch and VTL affected cooperativeness and trustworthiness was different enough to determine that these two constructs overlap, but are not synonymous. Together, these studies show that despite the fact that masculine men tend to win political elections and run large and successful companies, they are viewed as uncooperative and untrustworthy. Future research should investigate if those who win political elections and run successful companies do so because they keep more than their fair share of money. / Thesis / Master of Science (MSc)

While hearing aids are optimized for listening to and hearing speech in noisy environ- ments, there are still many challenges when using hearing aids to listen to music. This could mean that hearing impaired individuals do not perceive music the same way a normal hearing person would. When two musical tones are played simultaneously at equal presentation levels, the tone with the higher frequency will be perceived as more salient for a normal hearing person. This phenomenon is referred to as the high voice superiority effect. This study examined how different types of hearing loss affect the neural pitch salience profile obtained with a computational model of the auditory periphery. More specifically, the high voice superiority effect was examined by generating neural pitch salience profiles for different combinations of simultaneous tones at different sound presentation levels. To model other aspects of hearing aid processing, an Analog to Digital Converter (ADC) and simple noise reduction filter were added to some of the simulations. The results show that less severe hearing loss types tend to have pitch salience profiles closer to normal after hearing aid amplification. The addition of the ADC to the simulation seems to have little effect on the pitch salience, whereas the noise reduction filter has a noticeable effect on how closely the pitch salience profile matches that of a normal hearing ear. For each different type of hearing loss there appears to be a trade-off between the ability of the upper tone and the lower tone to match normal hearing performance. Along with simulated piano tone results, pitch salience results are shown for live recordings of several instruments through hearing aids. The recordings are compared to ideal versions of the instrument parts. This study provides a starting point to improve hearing aid processing for music perception. / Thesis / Master of Applied Science (MASc) / While hearing aids are optimized for listening to speech, they still face challenges when listening to music. This study examined how different types of hearing loss and hearing aid amplification affect music perception, using the measure of neural pitch salience. The results show that less severe hearing loss types tend to have pitch salience profiles closer to normal after amplification. Along with simulated piano tone results, pitch salience results are shown for live recordings of several instruments through hearing aids. The recordings are compared to ideal versions of the instrument parts. This study provides a starting point to improve hearing aid processing for music perception.

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