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Results for “Auditory Perception”

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At least 1,081 records · Page 60Linked to original sources
PubMed1978

Auditory sensitivity, equal loudness, temporal resolving power, and vocalizations in the house finch (Carpodacus mexicanus).

Absolute thresholds for pure tones were measured in four house finches by use of avoidance conditioning and a modified method of limits. Response reaction time to each tone presentation served as a data base for generating a family of "equal loudness" contours. Temporal resolving power was measured in two additional birds and compared with similar measures in man. The results are discussed in relation to previous studies of vocalizations in the house finch, and the average power spectra of selected individual vocalizations are presented.

Animals↗
PubMed1982

Auditory signal detection and decision processes in the nervous system.

Neuronal unit activity was recorded from auditory nuclei, and dorsal hippocampus, and the cerebellum in rabbits behaviorally detecting a threshold-level constant intensity white noise stimulus. Stimulus-evoked neuronal unit activity was present and identical on both detection and nondetection trials in auditory nuclei but was dichotomous in the hippocampus and in the cerebellum, the latter two systems predicting the occurrence of behavioral detection. It is concluded that the behavioral absolute auditory threshold is not determined by differential activation of neurons in the primary auditory relay nuclei.

Animals↗
PubMed1998

Age-related changes in temporal resolution: envelope and intensity effects.

Gap-detection thresholds were determined for 10 younger and 10 older adults at two sensation levels (40 and 60 dB SL) for tone pips with Gaussian amplitude envelopes whose standard deviations were 0.5, 1, 1.5, and 2 ms. Gap-detection thresholds were larger for the older participants under all conditions. For all participants, gap-detection thresholds increased with the standard deviation of the Gaussian amplitude envelope, were relatively independent of sensation level, and were independent of the degree of hearing loss. Because spectral splatter decreases with increasing standard deviation of the Gaussian amplitude envelope, the age-related differences in gap-detection cannot be attributed to differences between how young and old listeners are affected by off-frequency cues. Furthermore, the consistent age difference in gap-detection at all amplitude envelope standard deviations was shown to be incompatible with the hypothesis that temporal integration time is longer for older listeners.

Adult↗
PubMed1996

Evidence for a sound movement area in the human cerebral cortex.

Human listeners can localize sounds by the difference in both arrival time (phase) and loudness between the two ears. Movement of the sound source modulates these cues, and responses to moving sounds have been detected in animals in primary auditory cortex and in humans in other cortical areas. Here we show that detection of changes in the interaural phase or amplitude difference occurs through a mechanism distinct from that used to detect changes in one ear alone. Moreover, a patient with a right hemisphere stroke is unable to detect sound movement, regardless of whether it is defined by phase or by loudness cues. We propose that this deficit reflects damage to a distinct cortical area, outside the classical auditory areas, that is specialized for the detection of sound motion. The deficit is analagous to cerebral akinotopsia (motion blindness) in the visual system, and so the auditory system may, like the visual system, show localization of specialized functions to different cortical regions.

Aged↗
PubMed2003

Acoustic factors govern developmental sharpening of spatial tuning in the auditory cortex.

Auditory localization relies on the detection and interpretation of acoustic cues that change in value as the head and external ears grow. Here we show that the maturation of these structures is an important determinant for the development of spatial selectivity in the ferret auditory cortex. Spatial response fields (SRFs) of high-frequency cortical neurons recorded at postnatal days (P) 33-39 were broader, and transmitted less information about stimulus direction, than in older ferrets. They also exhibited slightly broader frequency tuning than neurons recorded in adult animals. However, when infant neurons were stimulated through virtual ears of adults, SRFs sharpened significantly and the amount of transmitted information increased. This improvement was predicted by a model that generates SRF shape from the localization cue values and the neurons' binaural spectrotemporal response properties. The maturation of spatial response characteristics in auditory cortex therefore seems to be limited by peripheral rather than by central factors.

Acoustic Stimulation↗
PubMed2006

Spectrally enhanced acoustic environment disrupts frequency representation in cat auditory cortex.

Sensory environments are known to shape nervous system organization. Here we show that passive long-term exposure to a spectrally enhanced acoustic environment (EAE) causes reorganization of the tonotopic map in juvenile cat auditory cortex without inducing any hearing loss. The EAE consisted of tone pips of 32 different frequencies (5-20 kHz), presented in random order at an average rate of 96 Hz. The EAE caused a strong reduction of the representation of EAE frequencies and an over-representation of frequencies neighboring those of the EAE. This is in sharp contrast with earlier developmental studies showing an enlargement of the cortical representation of EAEs consisting of a narrow frequency band. We observed fewer than normal appropriately tuned short-latency responses to EAE frequencies, together with more common long-latency responses tuned to EAE-neighboring frequencies.

Acoustic Stimulation↗
PubMed2003

Neural correlates of cross-modal binding.

Little is known about how the brain binds together signals from multiple sensory modalities to produce unified percepts of objects and events in the external world. Using event-related functional magnetic resonance imaging (fMRI) in humans, we measured transient brain responses to auditory/visual binding, as evidenced by a sound-induced change in visual motion perception. Identical auditory and visual stimuli were presented in all trials, but in some trials they were perceived to be bound together and in others they were perceived as unbound unimodal events. Cross-modal binding was associated with higher activity in multimodal areas, but lower activity in predominantly unimodal areas. This activation pattern suggests that a reciprocal and 'competitive' interaction between multimodal and unimodal areas underlies the perceptual interpretation of simultaneous signals from multiple sensory modalities.

Acoustic Stimulation↗
PubMed2002

An electrophysiological measure of temporal resolution in normal subjects using frequency modulated signals.

This investigation was conducted to determine whether an exogenous event-related potential called the mismatch negativity (MMN) would change systematically in response to frequency-modulated signals with varying temporal properties. Both N1 and P2 waveforms were recorded for 50-ms frequency-modulated signals from normal hearing listeners. The standard stimuli for this investigation were continuous sweep tones with center frequencies of 1000 Hz that traversed a frequency range of 200 Hz in a single step. The rare stimuli were signals that traversed the same frequency range in two, four, six, or eight discrete steps. Results suggest that for the 10 participants, 1) the mean MMN peak-to-peak amplitude and mean area decreased significantly with decreases in step duration, 2) MMN area amplitude was the best indicator of psychophysical performance for the two magnitude measures, and 3) MMN onsets and peak latencies did not show either a significant increase or decrease in latency as step duration decreased.

Adult↗
PubMed2003

Effects of noise and reverberation on the precedence effect in listeners with normal hearing and impaired hearing.

The purpose of this study was to determine the effects of reverberation and noise on the precedence effect in listeners with hearing loss. Lag burst thresholds (LBTs) for 4-ms noise bursts were obtained for 2 groups of participants: impaired hearing and normal hearing. Data were collected in reverberant and anechoic environments in quiet and noise, at sensation levels of 10, 20, 30, 40, and 50 dB. Results indicated a significant effect of reverberation on LBTs for both participant groups. LBTs increased with sensation level in the reverberant environment and decreased with increasing sensation level in the anechoic environment. There was no effect of hearing loss on LBTs. When the change in LBT due to noise was compared, the effect of noise depended on group and environment, with a greater effect of noise on the performance of listeners with impaired hearing. It is likely that the ability to fuse direct sounds and early reflections is degraded in listeners with impaired hearing and that this contributes to the difficulties experienced by these listeners in reverberation and noise.

Adult↗
PubMed2004

Subtypes of severe speech and language impairments: psychometric evidence from 4-year-old children in The Netherlands.

Most, if not all, of the studies of subtypes of children with language impairments have been conducted with English-speaking children. The possibility and validity of identified subtypes for non-English clinical populations are, as yet, unknown. This study was designed to provide cross-linguistic evidence of language subtypes. A broad battery of tests was administered to measure the phonological, lexical, morphosyntactic, semantic, discourse, and pragmatic abilities of a representative sample of 110 4-year-old Dutch children who had been previously diagnosed as severely speech and language impaired. Principal components analyses revealed 4 subtypes of speech and language impairments, which were labeled lexical-semantic, speech production, syntoctic-sequential, and auditory perception. These results were consistent with recent theoretical claims about the classification of English-speaking children with speech and language impairments.

Child, Preschool↗
PubMed2005

Effects of age and hearing loss on gap detection and the precedence effect: narrow-band stimuli.

Deficits in temporal resolution and/or the precedence effect may underlie part of the speech understanding difficulties experienced by older listeners in degraded acoustic environments. In a previous investigation, R. Roberts and J. Lister (2004) identified a positive correlation between measures of temporal resolution and the precedence effect, specifically across-channel gap detection (as measured dichotically) and fusion. Across-channel gap detection may also be measured using frequency-disparate markers. Thus, the present investigation was designed to determine if the relation is specific to dichotic gap detection or may generalize to all types of across-channel gap detection. Gap-detection thresholds (GDTs) for fixed-frequency and frequency-disparate markers and lag-burst thresholds (LBTs) were measured for 3 groups of listeners: young with normal hearing sensitivity (YNH), older with normal hearing sensitivity (ONH), and older with sensorineural hearing loss (OIH). Also included were conditions of diotic and dichotic GDT. Largest GDTs were measured for the frequency-disparate markers, whereas largest LBTs were measured for the fixed-frequency markers. ONH and OIH listeners exhibited larger frequency-disparate and dichotic GDTs than YNH listeners. Listener age and hearing loss appeared to influence temporal resolution for frequency-disparate and dichotic stimuli, which is potentially important for the resolution of timing cues in speech. Age and hearing loss did not significantly influence fusion as measured by LBTs. Within each participant group, most GDTs and LBTs were positively, but not significantly, correlated. For all participants combined, across-channel GDTs and LBTs were positively and significantly correlated. This suggests that the 2 tasks may rely on a common across-channel temporal mechanism.

Acoustic Stimulation↗
PubMed2006

Effect of memory support and elicited production on fast mapping of new words by adolescents with Down syndrome.

PURPOSE: The purpose of this study was to determine whether memory support and elicited production differentially benefited fast mapping of new vocabulary (comprehension, production accuracy, and speed) in adolescents with Down syndrome (DS) compared with typically developing (TD) children matched for syntax comprehension. The study also examined predictors of individual difference within groups. METHOD: The ability of 19 adolescents with DS to fast map new noun vocabulary was compared with 18 TD children matched for syntax comprehension. The effects of memory support (5 examiner repetitions of the novel word vs. 1) and elicited production (2 repetitions by child vs. none) were evaluated in a repeated-measures design with counterbalancing of tasks. RESULTS: For novel word comprehension, low memory support impaired the TD but not DS participants. DS participants were slower to respond correctly in all conditions but benefited more from memory support than TD participants in speed of response. For novel word production, high memory support benefited all participants in the no-elicited-production condition. Elicited production improved performance equally in the 2 memory conditions. Standard comprehension measures predicted fast-mapped comprehension: vocabulary in the case of the DS group, syntax in the case of the TD group. Auditory short-term memory measures predicted fast-mapped production in the TD group but not the DS group. Hearing and grammatical morpheme comprehension predicted novel word production in the DS group. CONCLUSIONS: DS participants' speed of comprehension of fast-mapped words was differentially increased compared with the TD syntax-comprehension-matched group, by memory support. Elicited production improved production fast-mapping for all participants, and memory support improved it in the absence of elicited production. Comprehension predicted individual differences in fast-mapped comprehension in DS; in addition, hearing predicted production.

Adolescent↗