Response times have been used to explore cognitive and perceptual processes since 1850 (Donders, 1868). The technique has primarily been applied to humans, birds, and terrestrial mammals. Results from two studies are presented here that examine response times in bottlenose dolphins (Tursiops truncatus) and white whales (Delphinapterus leucas). One study concerned response times to stimuli well above the threshold of perceptibility of a stimulus, and the other concerned response times to stimuli near threshold. Two white whales (Delphinapterus leucas) and five Atlantic bottlenose dolphins (Tursiops truncatus) were presented stimuli well above threshold. The stimuli varied in type (tone versus pulse), amplitude, duration, and frequency. The average response time for bottlenose dolphins was 231.9 ms. The average response time for white whales was 584.1 ms. There was considerable variation between subjects within a species, but the difference between species was also found to be significant. In general, response times decreased with increasing stimulus amplitude. The effect of duration and frequency on response time was unclear. Two white whales (Delphinapterus leucas) and four Atlantic bottlenose dolphins (Tursiops truncatus) were given audiometric tests to determine masked hearing thresholds in open waters of San Diego Bay (Ridgway et al., 1997). Animals were tested at six frequencies over a range from 400 Hz to 30 kHz using pure tones. Hearing thresholds varied from 87.5 dB to 125.5 dB depending on the frequency, masking noise intensity and individual animal. At threshold, median response time across frequencies within each animal varied by about 150 ms. The two white whales responded significantly slower (∼670 msec, p<0.0001) than the four dolphins (∼410 msec). As in terrestrial animals, reaction time became shorter as stimulus amplitude increased (Wells, 1913; Stebbins, 1966). Across the two studies, the dolphins as a group were faster in the abovethreshold study than in the nearthreshold study. White whales had longer response times than bottlenose dolphins in both studies. Analysis of response time with an allometric relation based on weight shows that the difference in weight can explain a significant part of the difference in response time.

Thesis--Göteberg. / Extra t.p. with thesis statement inserted. Includes bibliographical references (p. 186-195).

Thesis (M. Communication Pathology)--University of Pretoria, 2009. / Includes bibliographical references.

Thesis (M.A.)--York University, 2001. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 74-85). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ71633.

The purpose of this study was to investigate the stability of hearing aid benefit, as measured by the Abbreviated Profile of Hearing Aid Benefit (APHAB; Cox & Alexander, 1995), between three months post hearing aid fitting and at next the annual audiological re-evaluation. The annual re-evaluation was at least, and as close to nine months as possible, after the previous audiological. The maximum time between the two evaluations was 18 months. Thirty-six hearing aid patients participated in this study. The participants were both male andfemale, and were fitted monaurally or binaurally with hearing aid(s). All participants had sensorineural hearing loss with no ongoing or permanent conductive or retrocochlear pathology. The APHAB scale was administered at the three month hearing aid check (HAC) and again at the annual audiometric re-evaluation. Analysis of covariance (ANCOVA), with length of time between the three month hearing aid check (HAC) and the next audiological re-evaluation as a covariate, was used to examine the main effects of time of administration and subscale [e.g., ease of communication (EC), reverberant conditions (RV), background noise (BN), and aversiveness of sounds (AV) and their interactions. Results revealed a significant reduction in the mean benefit scores between the 3-month HAC and annual re-evaluation APHAB administration. It is hypothesized that the causal factor of the decrease in benefit in the EC, RV, & BN are multifactorial. These reductions in benefits may be do to the Hawthorne effect, unrealistic hearing aid benefit expectations by the participants, or a heightened expectation of hearing aid benefit due to the financial expense. It should also be noted, however, that using the 90% confidence interval for "true" clinical benefit, 21 of the participants maintained stable benefit over the course of the study. Finally, although not statistically significant, the fourth APHAB scale, aversiveness of sounds (AV), improved over time.

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Vocal communication sounds are an important class of signals due to their role in social interaction, reproduction, and survival. The higher-order mechanisms by which our auditory system detects and discriminates these sounds to generate perception is still poorly understood. The auditory cortex is thought to play an important role in this process, and our current work provides new evidence that the auditory cortex changes its neural representation of sounds that are acquired in natural social contexts. We use a mouse ultrasonic communication system between pups and adult females to elucidate this. We record single neurons in the auditory cortex of awake mice, and assess the cortical differences between animals that either do (mothers) or do not (naïve virgins) recognize the pup ultrasounds as behaviorally relevant. We then evaluate the role that pup experience and the maternal physiological state play in this cortical plasticity. Finally, we develop a model to predict the responses to pup vocalizations as a way to segregate the diversity of cortical neuronal responses in the hope of more clearly assessing their roles in processing acoustic features. Our results demonstrate the detailed nature by which the core auditory cortex processes natural vocalizations, showing how it changes to represent behavioral relevance.

Tone pairs constructed with the frequencies of the overtones moving in opposition to the missing fundamental frequencies they imply, produce expertise differences in the tracking of pitch direction. One interpretation of this result is that it arises as a function of rudimentary differences in the perceptual systems of musicians and non-musicians. Several experiments suggest instead a more embodied source of expertise to be found in vocal mediation such that the effect of musical experience in these tasks is the result of the most salient action of musicians: making sound. / x, 87 leaves : ill. ; 29 cm

This study investigated the neural correlates of memory for human nonlinguistic emotional vocalizations as a function of individual differences in trait anxiety and depression. 20 healthy subjects (female; aged 18-30) free from neurological impairments or psychiatric illness underwent MRI scanning to obtain T1 structural images of their brain, and participated in a subsequent behavioral memory task outside the scanner. Volumetry of the hippocampus and amygdala was performed using a validated protocol. We found emotional vocalizations were better remembered than neutral ones, with performance for negative better than positive. Memory performance for emotional items was associated with hippocampal volume, with no association between memory and I amygdala volume detected. Differences in anxiety or depression had no influence on memory or volume. These results lay the groundwork for future functional neuroimaging work to investigate the neural correlates of memory, personality, and brain structure volume in healthy and clinical populations.

No description available.