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PubMed1983

Central auditory processing. I. Ear dominance--a perceptual or an attentional asymmetry?

The phenomenon of ear dominance for pitch described by Efron and Yund has been attributed by them to an asymmetry of sensory origin in the binaural integration of dichotic tone pairs. An explanation of this phenomenon in terms of an attentional bias is rejected on the basis of two experiments where the possibility of such bias was excluded. These and other experiments indicate that a simple explanation of this ear dominance in terms of a hemispheric specialization in the processing of tonal stimuli also must be rejected.

Attention↗
PubMed1989

An auditory Stroop effect for pitch, loudness, and time.

Increased reaction time to pitch, loudness, or duration of an auditorily presented word whose meaning is in conflict with the response label (i.e., high/low, loud/soft, or fast/slow) demonstrates an auditory Stroop effect. Fifteen normal adults participated in an auditory Stroop test. Analysis of reaction time data supports the existence of an auditory Stroop effect for pitch and loudness, but not duration. The interaction between psychoacoustic and semantic attributes of speech stimuli is discussed.

Adult↗
PubMed1981

Auditory event-related potentials in schizophrenia and depression.

Event-related potentials in two auditory target detection paradigms and two auditory paradigms without overt tasks were studied in 22 schizophrenic, 21 depressed, and 28 matched control subjects meeting Research Diagnostic Criteria. In the target detection paradigms, schizophrenics showed a pattern of reduced N120 amplitude and shorter P200 latency to frequently occurring tones, and reduced P300 and Slow Wave amplitude to infrequent target and nontarget tones. This pattern is consistent with impaired selective attention for stimuli. For depressed patients these variables were generally intermediate between those of schizophrenics and controls. In the other paradigms N120 latency was greater for schizophrenics, and P200 amplitude was less for depressed patients.

Adult↗
PubMed1995

Tone discrimination performance in schizophrenic patients and normal volunteers: impact of stimulus presentation levels and frequency differences.

Psychophysical and cognitive studies carried out in schizophrenic patients show high within-group performance variance and sizable differences between patients and normal volunteers. Experimental manipulation of a target's signal-to-noise characteristics can, however, make a given task more or less difficult for a given subject. Such signal-to-noise manipulations can substantially reduce performance differences between individuals. Frequency and presentation level (volume) changes of an auditory tone can make a sound more or less difficult to recognize. This study determined how the discrimination accuracy of medicated schizophrenic patients and normal volunteers changed when the frequency difference between two tones (high frequency vs. low frequency) and the presentation levels of tones were systematically degraded. The investigators hypothesized that each group would become impaired in its discrimination accuracy when tone signals were degraded by making the frequencies more similar and the presentation levels lower. Schizophrenic patients were slower and less accurate than normal volunteers on tests using four tone levels and two frequency differences; the schizophrenic patient group showed a significant decrement in accuracy when the signal-to-noise characteristics of the target tones were degraded. The benefits of controlling stimulus discrimination difficulty in functional imaging paradigms are discussed.

Adult↗
PubMed1990

Neural representation of sound amplitude in the auditory cortex: effects of noise masking.

Single auditory cortical neurons express their sensitivity to the amplitude of a preferred-frequency tone pulse as either a monotonic, saturating intensity profile or as a non-monotonic, bell-shaped intensity function. In the presence of continuous, wideband noise masking, the tone intensity profile is displaced toward higher tone levels. The magnitude of the tone threshold adjustments brought about by increments in noise level very closely match the elevations in noise amplitude. The mechanisms underlying the threshold adjustments likely include neural adaptation. This is because the tone threshold shifts seen in the spike count data are paralleled by spike latency data, and because recovery of tonal sensitivity following noise offset proceeds in a negatively-accelerating fashion. In some instances, the slope of the masked tone intensity profile is greater than that for unmasked tones. For masked tone levels evoking submaximal responses, this has the consequence that cortical responses to masked tones are somewhat more salient than those for unmasked tones of comparable suprathreshold level. These observations bolster our understanding of the psychophysics of noise-masking in normal listeners, and they provide a partial explanation of the difficulty shown by patients with temporal lobe lesions in discriminating signals in noise.

Animals↗
PubMedDate not supplied

Attributes of tinnitus and the acceptance of masking.

Various characteristics of tinnitus were surveyed to determine whether they were associated with the acceptance of masking, which is used as a relief procedure for tinnitus. The characteristics considered were duration, loudness match, minimum masking level, and residual inhibition. Data for the characteristics of tinnitus were obtained from the Tinnitus Data Registry at the Oregon Hearing Research Center, which contains information on 784 tinnitus patients. The acceptance of masking was determined by each individual patient based on actual tests with wearable masking units. Variations in the individual characteristics listed above were not found to be significantly associated with the acceptance of masking and thus should not be used a priori to deny patients the opportunity for possible relief of their tinnitus. A masking indicator was found to be significantly (P = .03) associated with the acceptance of masking. This masking indicator is obtained by subtracting the loudness match of the tinnitus from the minimum masking level. When the masking indicator was 10 dB or less, the acceptance of masking was in excess of 50%. The data presented may help to dispel some current misconceptions about the masking of tinnitus.

Consumer Behavior↗
PubMed1982

Processing the intensity of dichotic syllables.

Subjects were required to match the intensity levels of the left- and right-ear members of dichotically presented nonsense syllables. When subjects matched the overall average intensities of a sequence of differing dichotic pairs no ear differences were observed. When repetitions of single dichotic pairs were matched right-ear syllables were judged louder than left-ear syllables. The results support a model predicting left-hemisphere superiority in a task permitting higher-level encoding of speech input.

Cerebral Cortex↗
PubMed1985

Music draws attention to the left and speech draws attention to the right.

Providing free-field music input prompts right-handers to attend to their left side in a loudness-matching task that requires no musical analysis. Conversely, speech prompts rightward attention. The processes inferred are akin to the attentional asymmetry demonstrated in the syndrome of hemispatial neglect.

Adult↗
PubMed1989

Stimulus intensity, attentional instructions, and the ear advantage during dichotic listening.

The present experiment was designed to investigate the effects of the following two variables on the identification of dichotically presented CV syllables: (1) the relative difference in intensity levels of the stimuli presented to the two ears and (2) the instructions to attend to both ears or to focus attention on one ear. As expected for a verbal task, more CV's were identified from the right ear than from the left ear. Furthermore, identification of stimuli presented to one ear improved when (1) those stimuli were relatively higher in volume than the stimuli presented to the other ear and (2) when subjects were instructed to focus attention on only that ear rather than distribute attention across both ears. Of particular importance is the finding that the effects of relative stimulus intensity are the same under conditions of focused attention as under conditions of divided attention. This finding is inconsistent with an attention explantation of the relative intensity effects. Instead, the results are consistent with a model of dichotic listening in which ear of stimulus presentation and relative stimulus intensity influence a perceptual stage of information processing and attentional instructions influence a subsequent response selection stage.

Adult↗
PubMed1986

P300 and alcohol consumption in normals and individuals at risk for alcoholism. A preliminary report.

Pairs of college student subjects (36 male, 36 female) were matched on age, sex, and personal drinking history. One pair member had a parent who met the DSM III criteria of alcoholism, while the other pair member had no close alcoholic relative. The P300 event-related brain potential (ERP) was obtained from each subject with auditory stimuli in an "oddball" paradigm. Target stimuli occurred randomly on 20% of the trials in a frequency discrimination task, a relatively easy intensity discrimination task, and a more difficult intensity discrimination task. Subjects indicated when the target items occurred by moving their index finger. No significant overall effects were obtained for family history for either P300 latency or amplitude. P300 latency increased and amplitude decreased with increases in the reported amount of alcohol consumption in all subjects only for the difficult intensity task but were statistically significant only for individuals with a negative family history for alcoholism.

Adolescent↗
PubMedDate not supplied

Orienting, habituation, sensitisation, and dishabituation in the electrodermal system of consecutive, drug free, admissions for schizophrenia.

Thirty-three consecutive admissions for schizophrenia with PSE diagnoses and free of neuroleptics were compared with 31 hospital staff for distinguishing features of bilateral electrodermal activity to a sequence of mild tones followed by a sequence of conspicuous tones with variation of temporal parameters. To mild tones most patients were either non-responders or non-habituators whereas most controls were habituators or non-habituators. To conspicuous tones patients as a group were more responsive but without the features of sensitisation to a test stimulus shown by controls. Patients as a group had more non-specific response and higher levels of skin conductance which showed less adaptation than controls. To a large extent previously reported difference in response latencies, rise-times and half-recovery times would appear to be a function of habituation rate. Patient -control differences may reflect anxiety and stress in patients, though lateral asymmetries in activity have a deeper salience for the nature of schizophrenia.

Acoustic Stimulation↗
PubMed1984

The augmenting/reducing phenomenon in the auditory evoked potential.

Auditory evoked potentials (AEPs) were recorded to 4 intensities of tones (70, 80, 90, 100 dB) in 22 normal subjects. Augmenting (generally increasing amplitude with increasing stimulus intensity) and reducing (a levelling off or decrease in amplitude with increasing stimulus intensity) were found to occur at both central (Cz, C3, C4) and temporal (T3, T4) placements, regardless of which peak or peak-through measure was examined. There were generally low levels of agreement between central amplitude/intensity response patterns and those at temporal placements. An individual was seldom classified the same way (i.e. augmenter or reducer) when the augmenting or reducing was assessed using different AEP measures. These results suggest that in the AEP the suitability of the conventional definition and the validity of certain interpretations of augmenting/reducing are questionable.

Adult↗
PubMed1990

Facial electromyographic reactions and autonomic activity to auditory stimuli.

This study explored whether high- and low-intensity auditory stimuli evoke different facial electromyographic reactions and autonomic responses. Subjects were repeatedly exposed to 95-dB and 75-dB tones (1000 Hz, 40 ms rise and fall times) while their facial electromyograms from the corrugator and zygomatic muscle regions, heart rate, skin conductance responses, skin conductance half recovery time and ratings were measured. The 95-dB tone evoked a "negative" reaction with increased corrugator activity and an autonomic response pattern that carried aspects of a defense reaction, that is, slowly habituating skin conductance responses with retarded recovery rate and an initial tendency to heart rate acceleration. Furthermore, the 95-dB tone was rated as unpleasant. The 75-dB tone elicited an orienting response indicated by a distinct heart rate deceleration and fast habituating skin conductance responses with a relatively short recovery time. Thus, the present study demonstrated that the facial electromyographic technique is sensitive to simple environmental stimuli such as auditory stimuli and that the facial response is consistent with the autonomic response patterns and the experience of the stimuli.

Acoustic Stimulation↗
PubMed1993

Stimulus duration and the sensory memory trace: an event-related potential study.

The mismatch negativity (MMN) of the auditory event-related potential is elicited when a stimulus deviates from that represented by the neural memory trace developed by preceding stimuli. The effect of stimulus duration on this trace was studied by presenting sequences of 1000 Hz, 80 dB stimuli to subjects engaged in silent reading. Stimuli were, in different blocks, either of 4, 10, 30, 100 or 300 ms in duration. 5% of the stimuli were deviants which were either higher in frequency (1050 Hz) or lower in intensity (70 dB) than the standards. The "silent" period between two successive stimuli was constant at 300 ms. The minimum stimulus duration with which a distinct MMN was elicited by frequency deviants was 30 ms, but the MMN amplitude was not increased when stimulus duration was further prolonged. In contrast, the intensity MMN was elicited even when stimulus duration of 10 ms and its amplitude increased as a function of stimulus duration. Reaction times and hit percentages in response to these deviant stimuli in a separate discrimination task displayed analogous patterns of results.

Adult↗
PubMed1996

UCS inflation and human aversive autonomic conditioning.

Fifty students participated in a differential conditioning paradigm. In the first part of the experiment, one neutral slide (CS+) was paired with a tone (UCS) and another neutral slide (CS-) was never followed by a tone. During the subsequent inflation phase, unsignalled UCSs gradually increased in strength for the inflation group while they were kept constant for the control group. During extinction trials, the inflation group initially showed relatively stronger UCS expectancies on the CS+ trials than the control group. In contrast to what was predicted, the UCS inflation procedure did not result in stronger conditioning effects of the skin conductance response compared to the control procedure. The effectiveness of the UCS inflation procedure was not related to trait anxiety.

Acoustic Stimulation↗
PubMed1982

Cochlear potentials in the Bronx waltzer mutant mouse.

The Bronx waltzer mutant mouse has a unique cochlear abnormality in which the outer hair cells appear normal but the inner hair cells are absent. Potentials recorded from the round window indicate that the gross cochlear nerve action potential is very small or absent and cochlear microphonics are present but of small amplitude. Positive and negative summating potentials can both be recorded, indicating that mammalian outer hair cells are capable of producing both positive and negative DC potentials.

Animals↗
PubMed1995

Time course of loudness in tone patterns is automatically represented by the human brain.

The present study investigated the neural mechanisms of intensity coding by presenting human subjects repetitively with tone pairs consisting of two tones differing in intensity. The first tone was higher in sound pressure level than the second (70 versus 58 dB SPL). Infrequent order reversals of the two tones elicited the mismatch negativity (MMN), an event-related brain potential probe of preattentive auditory sensory memory. This finding indicates that the human auditory system automatically encodes information about the time course of intensity within tone patterns into neural representations.

Adult↗
PubMed1979

The effects of ethanol and meperidine on auditory evoked potentials.

The effects of ethanol and meperidine on the auditory evoked potential (AEP) to stimuli of different intensities were investigated. Sixteen normal male volunteers received ethanol, 0.8 ml/kg, 100 mg meperidine, and a placebo on different days in a double-blind study. AEPs were recorded from Fz, Cz and Pz electrode placements. The stimuli were 500 msec 1000 Hz tones at 50, 60, 70 and 80 dB sound pressure level presented in a pseudo-random sequence. Meperidine had no significant effect on AEP variables. Ethanol reduced AEP activity between 24 and 250 msec but had no effect on the sustained potential measured between 300 and 450 msec.

Adult↗