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H O'Malley

Publications and source records attributed to H O'Malley.

9 recordsLinked to original sources
PubMed1998

Cross-modality matching and the loudness growth function for click stimuli.

Loudness-intensity functions for click stimuli were obtained from 30 adult listeners having normal (n = 10), flat (n = 10), or sloping (n = 10) high-frequency cochlear hearing loss configurations. The procedure of cross-modality matching (CMM) between loudness and perceived line length [R. P. Hellman and C. H. Meiselman, J. Speech Hear. Res. 31, 605-615 (1988); J. Acoust. Soc. Am. 88, 2596-2606 (1990); J. Acoust. Soc. Am. 93, 966-975 (1993)] was used to validate their loudness growth functions. Mean group loudness exponents were similar to those reported in recent investigations that utilized pure tone stimuli, further supporting the validity and reliability of the CMM task as an estimate of the loudness growth function. The results also suggest that the mean loudness function for clicks is similar to the function obtained with tonal stimuli at least for listeners with moderately impaired hearing or better. Moreover, CMM produced less variability than the more conventional psychophysical methods of magnitude estimation and production for the groups with cochlear hearing loss. Toward direct application of the CMM technique, in lieu of absolute exponential slope values, the individually determined loudness growth function over a range of intensities should be compared to the normal mean functions for calculations of deviations.

Acoustic Stimulation↗
PubMed1998

Streptokinase in acute stroke: effect on reperfusion and recanalization. Australian Streptokinase Trial Study Group.

The Australian Streptokinase Trial was a randomized, double-blind, placebo-controlled trial, in which streptokinase (SK, 1.5 million IU I.V.) was given within 4 hours of stroke onset. In a subset of 37 patients, 99mTc-labeled D,L-hexamethylpropylene amine oxime single-photon emission computed tomography (SPECT) and/or transcranial Doppler (TCD) studies were performed before and after therapy to test the hypothesis that SK may improve the hemodynamic measures of reperfusion/recanalization rates (TCD parameter) within 24 hours. Eighteen patients received SK and 19 placebo. Baseline characteristics were similar in both groups, and there were no differences in clinical outcomes assessed at 3 months after stroke. Although there was no increase in the group mean perfusion defect or volume on SPECT after thrombolytic therapy, a larger number of patients demonstrating the combined end point of reperfusion or recanalization was seen in the SK group (13/14, 93%) than in the placebo group (7/14, 50%; p = 0.01). Although SK given within 4 hours of acute ischemic stroke appears to improve arterial patency/tissue reperfusion, this effect is neither early nor extensive enough to influence overall clinical outcome.

Acute Disease↗
PubMed1997

The relationship between loudness intensity functions and the click-ABR wave V latency.

OBJECTIVE: To assess the relationship of loudness growth and the click-evoked auditory brain stem response (ABR) wave V latency-intensity function (LIF) in listeners with normal hearing or cochlear hearing loss. The effect of hearing loss configuration on the intensity functions was also examined. DESIGN: Behavioral and electrophysiological intensity functions were obtained using click stimuli of comparable intensities in listeners with normal hearing (Group I; n = 10), and cochlear hearing loss of flat (Group II; n = 10) or sloping (Group III; n = 10) configurations. Individual intensity functions were obtained from measures of loudness growth using the psychophysical methods of absolute magnitude estimation and production of loudness (geometrically averaged to provide the measured loudness function), and from the wave V latency measures of the ABR. RESULTS: Slope analyses for the behavioral and electrophysiological intensity functions were separately performed by group. The loudness growth functions for the groups with cochlear hearing loss approximated the normal function at high intensities, with overall slope values consistent with those reported from previous psychophysical research. The ABR wave V LIF for the group with a flat configuration of cochlear hearing loss approximated the normal function at high intensities, and was displaced parallel to the normal function for the group with sloping configuration. The relationship between the behavioral and electrophysiological intensity functions was examined at individual intensities across the range of the functions for each subject. A significant relationship was obtained between loudness and the ABR wave V LIFs for the groups with normal hearing and flat configuration of cochlear hearing loss; the association was not significant (p = 0.10) for the group with a sloping configuration of cochlear hearing loss. CONCLUSION: The results of this study established a relationship between loudness and the ABR wave V latency for listeners with normal hearing, and flat cochlear hearing loss. In listeners with a sloping configuration of cochlear hearing loss, the relationship was not significant. This suggests that the click-evoked ABR may be used to estimate loudness growth at least for individuals with normal hearing and those with a flat configuration of cochlear hearing loss. Predictive equations were derived to estimate loudness growth for these groups. The use of frequency-specific stimuli may provide more precise information on the nature of the relationship between loudness growth and the ABR wave V latency, particularly for listeners with sloping configurations of cochlear hearing loss.

Acoustic Stimulation↗
PubMed1988

Helping themselves.

Explore the source record for details and available documents.

Community Health Nursing↗
PubMed1979

Relationship between psychophysical tuning curves and "suppression".

This study examined two-tone unmasking and auditory frequency selectivity about 3 kHz for the purpose of demonstrating a qualitative relationship between the two. An adaptive 2IFC forward-masking procedure was used to collect psychophysical tuning curves (PTC's) and two-tone masking data under a quiet and noise condition for the same normal-hearing listeners. In the noise condition, a narrowband noise masker, centered one decade down from the probe, was gated on with the tonal masker(s). Kiang and Moxon [J. Acoust. Soc. Am. 55, 620-630 (1974)] have found that low-frequency narrowband noise serves to decrease the sharpness of electrophysiological tuning curves by affecting only the tip segments. The data for four highly practiced listeners indicate that the gated-noise masker was effective in broadening the PTC's and in lessening the magnitude of two-tone unmasking. The mutually reflected changes in tuning curves and in two-tone unmasking indicate a close relationship between frequency selectivity and unmasking: the greater the magnitude of unmasking above the center frequency of the PTC, the sharper the tuning of the PTC.

Adult↗
PubMed1977

Two-tone auditory spectral resolution.

Two component complex tones were synthesized so that each member of a complementary pair exhibited identical amplitude modulations; frequency modulations, however, were in opposite directions. Previous work has shown that the discriminability of the members of a complementary pair is related to the envelope-weighted differences in their instantaneous frequency functions. Listeners report that they base their discriminations upon differences in pitch between complementary two component signals. We assumed that the high discriminability found for moderate separations between the two component frequencies would not obtain if the components were resolved into separate critical bands. Thus we could define the just discriminable (75%) frequency separation as a direct estimate of spectral resolving power without recourse to assumptions about masking effectiveness, loudness summation, or other subjective changes thought to depend upon auditory spectral resolving power. Our findings indicate that resolution bandwidths resulting from the discriminability of complex tone pairs approximate the width of the traveling-wave envelope observed by von Békèsy. In light of our results, the implications for other critical bandwidth estimates are discussed.

Humans↗
PubMed1975

Effects of dichotically presented simulatneous synchronous and delayed auditory feedback on key tapping performance.

A selective replication of Tsunoda's (1966) application of the DAF key tapping paradigm to the study of functional auditory asymmetry was conducted. Present findings do not offer confirmation of Tsunoda's assertion that most subjects will exhibit performance disruption at a lower intensity level when a vowel is delayed at the right ear and when a pure tone is delayed at the left ear. In the present study, it was found that no difference existed between the pure tone and the vowel delayed to the left ear conditions in terms of performance deterioration. The significant difference in performance disruption between the vowel delayed to the right ear condition and the pure tone delayed to the right ear condition was interpreted to be suggestive of functional auditory asymmetry.

Auditory Perception↗