Biomedical subjects

Ken I McAnally

Publications and source records attributed to Ken I McAnally.

9 recordsLinked to original sources

PubMed2006

Learning and retention of associations between auditory icons and denotative referents: implications for the design of auditory warnings.

OBJECTIVE: This study examined the way in which the type and preexisting strength of association between an auditory icon and a warning event affects the ease with which the icon/event pairing can be learned and retained. BACKGROUND: To be effective, an auditory warning must be audible, identifiable, interpretable, and heeded. Warnings consisting of familiar environmental sounds, or auditory icons, have potential to facilitate identification and interpretation. The ease with which pairings between auditory icons and warning events can be learned and retained is likely to depend on the type and strength of the preexisting icon/event association. METHOD: Sixty-three participants each learned eight auditory-icon/denotative-referent pairings and attempted to recall them 4 weeks later. Three icon/denotative-referent association types (direct, related, and unrelated) were employed. Participants rated the strength of the association for each pairing on a 7-point scale. RESULTS: The number of errors made while learning pairings was greater for unrelated than for either related or direct associations, whereas the number of errors made while attempting to recall pairings 4 weeks later was greater for unrelated than for related associations and for related than for direct associations. Irrespective of association type, both learning and retention performance remained at very high levels, provided the strength of the association was rated greater than 5. CONCLUSION: This suggests that strong preexisting associations are used to facilitate learning and retention of icon/denotative-referent pairings. APPLICATION: The practical implication of this study is that auditory icons having either direct or strong, indirect associations with warning events should be preferred.

Adult↗

PubMed2005

Directed attention eliminates 'change deafness' in complex auditory scenes.

In natural environments that contain multiple sound sources, acoustic energy arising from the different sources sums to produce a single complex waveform at each of the listener's ears. The auditory system must segregate this waveform into distinct streams to permit identification of the objects from which the signals emanate [1]. Although the processes involved in stream segregation are now reasonably well understood [1, 2 and 3], little is known about the nature of our perception of complex auditory scenes. Here, we examined complex scene perception by having listeners detect a discrete change to an auditory scene comprising multiple concurrent naturalistic sounds. We found that listeners were remarkably poor at detecting the disappearance of an individual auditory object when listening to scenes containing more than four objects, but they performed near perfectly when their attention was directed to the identity of a potential change. In the absence of directed attention, this "change deafness" [4] was greater for objects arising from a common location in space than for objects separated in azimuth. Change deafness was also observed for changes in object location, suggesting that it may reflect a general effect of the dependence of human auditory perception on attention.

Adult↗

PubMed2005

Localization of virtual sound at 4 Gz.

INTRODUCTION: Acceleration directed along the body's z-axis (Gz) leads to misperception of the elevation of visual objects (the "elevator illusion"), most probably as a result of errors in the transformation from eye-centered to head-centered coordinates. We have investigated whether the location of sound sources is misperceived under increased Gz. METHOD: Visually guided localization responses were made, using a remotely controlled laser pointer, to virtual auditory targets under conditions of 1 and 4 Gz induced in a human centrifuge. As these responses would be expected to be affected by the elevator illusion, we also measured the effect of Gz on the accuracy with which subjects could point to the horizon. RESULTS: Horizon judgments were lower at 4 Gz than at 1 Gz, so sound localization responses at 4 Gz were corrected for this error in the transformation from eye-centered to head-centered coordinates. We found that the accuracy and bias of sound localization are not significantly affected by increased Gz. CONCLUSION: The auditory modality is likely to provide a reliable means of conveying spatial information to operators in dynamic environments in which Gz can vary.

Acceleration↗

PubMed2004

Auditory temporal pattern discrimination and reading ability.

The relation between reading ability and performance on an auditory temporal pattern discrimination task was investigated in children who were either good or delayed readers. The stimuli in the primary task consisted of sequences of tones, alternating between high and low frequencies. The threshold interstimulus interval (ISI) for discrimination of differences in the temporal properties of the sequences was measured. An ISI threshold was also measured in a control task that was identical to the primary task, except all tones in a control sequence had the same frequency. Delayed readers and good readers were equally able to discriminate the timing of the sequences at short ISIs, for both the primary and control tasks. Furthermore, the ISI thresholds were not correlated with the ability to read either irregular words or nonwords. These results suggest that reading ability is not related to the ability to track large and rapid frequency changes in auditory temporal patterns.

Auditory Pathways↗

PubMed2003

Utility of monaural spectral cues is enhanced in the presence of cues to sound-source lateral angle.

The contention that normally binaural listeners can localize sound under monaural conditions has been challenged by Wightman and Kistler (J. Acoust. Soc. Am. 101:1050-1063, 1997), who found that listeners are almost completely unable to localize virtual sources of sound when sound is presented to only one ear. Wightman and Kistler's results raise the question of whether monaural spectral cues are used by listeners to localize sound under binaural conditions. We have examined the possibility that monaural spectral cues provide useful information regarding sound-source elevation and front-back hemifield when interaural time differences are available to specify sound-source lateral angle. The accuracy with which elevation and front-back hemifield could be determined was compared between a monaural condition and a binaural condition in which a wide-band signal was presented to the near ear and a version of the signal that had been lowpass-filtered at 2.5 kHz was presented to the far ear. It was found that accuracy was substantially greater in the latter condition, suggesting that information regarding sound-source lateral angle is required for monaural spectral cues to elevation and front-back hemifield to be correctly interpreted.

Acoustic Stimulation↗

PubMed2003

Contrast sensitivity in subgroups of developmental dyslexia.

It has been proposed that developmental dyslexia is associated with a deficit in the magnocellular pathway of the visual system. Other research focuses upon the heterogeneous nature of developmental dyslexia, and evidence that subgroups of dyslexia may be identified based on selective deficits in specific component reading skills. This study tested the hypothesis that visual processing deficits may be present in different subgroups of developmental dyslexia by comparing the visual contrast sensitivity of three subgroups of dyslexic children (phonological, surface and mixed) and controls. The stimulus designed to measure magnocellular visual function was a low spatial frequency Gaussian blob, flickered sinusoidally at a temporal frequency of 8.33 Hz. The control stimulus, designed to measure parvocellular visual function, was a relatively high spatial frequency Gaussian windowed grating (8 c/deg) slowly ramped on and off. There were no significant differences between the groups of dyslexic and control children in contrast sensitivity to either stimulus. The findings do not support the existence of a magnocellular system deficit in dyslexia.

Child↗

PubMed2003

The overlay interference task and object-selective visual attention.

A series of experiments was carried out to examine object-based visual attention in an interference task. Observers were presented with two transparently overlapping equilateral triangles forming a "Star of David". One of these triangles was darker than the background, the other was lighter than the background. The observers were required to make a speeded choice response to the orientation of the darker triangle. The presence of the light triangle produced a robust interference effect that manifested as a slower response time. This effect was strongly modulated by the relative contrast of the target and distractor triangles. It was reduced when the light distractor triangle was separated in depth from the target triangle. Since the configuration rules out the possibility of 2-D spatial selection, it is concluded that object-based selection occurs in interference tasks and that the effectiveness of this selection is modulated by visual attributes that are not directly relevant to the task.

Adult↗

PubMed2003

Effect of hypobaric hypoxia on auditory sensitivity.

INTRODUCTION: Previous studies on the effect of hypobaric hypoxia on auditory sensitivity are not readily interpretable, in most cases because the potential effect of ambient pressure on stimulus level was not considered. In this study, auditory sensitivity to 1, 8, 12, and 16 kHz tones was compared between conditions of hypoxia and normoxia at the same simulated altitude (3700 m). METHOD: In the hypoxic condition, the partial pressure of oxygen in the inspired air was allowed to decrease with increasing altitude. In the normoxic condition, the partial pressure of oxygen was maintained at a level equivalent to that experienced at mean sea level (MSL). This comparison also controlled for any effect resulting from physiological consequences of hypobaria other than hypoxia (such as a change in middle-ear impedance). RESULTS: A small (2.57 dB) reduction in sensitivity across the frequency range tested was observed. CONCLUSION: A reduction in sensitivity of this magnitude would not be expected to have a large impact on the effectiveness of information transfer via the auditory modality.

Adult↗

PubMed2002

Timing of finger tapping to frequency modulated acoustic stimuli.

This study examined the timing of synchronous finger tapping to continuous frequency modulation (FM) and to click trains. Tapping to click trains was found to statistically significantly anticipate the acoustic stimulus. Tapping to continuous FM occurred before the instantaneous frequency rose through its mean value (i.e. at zero phase of the sinusoidal FM). The anticipation of zero phase of the FM was similar in magnitude to the anticipation of the click stimuli. However, there was a systematic departure from this timing when the FM depth was varied, the cause of which is unclear. The perceived timing of acoustic stimuli will influence the timing of motor responses to the stimuli. These results may therefore be relevant to the timing of perceptual centres of acoustic stimuli including speech.

Adult↗