Effects of time intervals and tone durations on auditory stream segregation

Adult listeners rated the difficulty of hearing a single coherent stream in a sequence of high (H) and low (L) tones that alternated in a repetitive galloping pattern (HLH-HLH-HLH...). They could hear the gallop when the sequence was perceived as a single stream, but when it segregated into two substreams, they heard H-H- ... in one stream and L-L- ... in the other. The onset-to-onset time of the tones, their duration, the interstimulus interval (ISI) between tones of the same frequency, and the frequency separation between H and L tones were varied. Subjects' ratings on a 7-point scale showed that the well-known effect of speed's increasing stream segregation is primarily due to its effect on the ISI between tones in the same frequency region. This has implications for several theories of streaming.     

Prelexical facilitation and lexical interference in auditory word recognition.

Phonological priming effects were examined in an auditory single-word shadowing task. In 6 experiments, target items were preceded by auditorily or visually presented, phonologically similar, word or nonword primes. Results revealed facilitation in response time when a target was preceded by a word or nonword prime having the same initial phoneme when the prime was auditorily presented but not when it was visually presented. Second, modality-independent interference was observed when the phonological overlap between the prime and target increased from 1 to 3 phonemes for word primes but not for nonword primes. Taken together, these studies suggest that phonological information facilitates word recognition as a result of excitation at a prelexical level and increases response time as a result of competition at a lexical level. These processes are best characterized by connectionist models of word recognition.     

The effect of tone duration on auditory stream formation

In a study in which the effect of tone duration on the formation of auditory streams was investigated, subjects were presented with 15-sec alternating pure-tone sequences (ABAB …) and were asked to orient their attention over the duration of the sequence toward hearing either a temporally coherent or a segregated percept. At stimulus offset, the subjects indicated whether their percept at the end of the stimulus had been that of a temporally coherent ABAB trill or that of segregated A and B streams. The experimental results indicated that the occurrence of stream segregation increases as (1) the duration of the A and B tones increases in unison and (2) the difference in duration between the A and B tones increases, with the duration differences between the tones producing the strongest segregation effects. A comparison of these experimental results with those of other studies strongly suggests that the time interval between the offset and onset of consecutive tones in the same frequency range is the most important temporal factor affecting auditory stream formation. Furthermore, a simulation of the experimental results by the Beauvois and Meddis (1996) stream segregation model suggests that both the tone duration effects reported here and Gestalt auditory grouping on the basis of temporal proximity can be understood in terms of low-level neurophysiological processes and peripheral-channeling factors.     

Acoustic interference in a recognition task

Phonetic or acoustic characteristics of stimuli in recall studies have consistently been shown to generate more interference over short intervals than semantic characteristics. We performed three experiments to determine whether this characteristic also applied to recognition processes over short intervals. Subjects were shown study lists of eight words and were asked to recognize which of those words recurred on subsequent eight-word lists. Delays varied from 0 to 100 s between study and test, with a rehearsal-preventing task inserted during the delays. Phonetic distractors generated greater interference than semantic distractors at all delay levels, and semantic distractors generated greater interference than random distractors. These distractor-type differences were not present in long-term recognition tasks. The deterioration in performance over time was considerably slower in these recognition experiments than in previous recall studies.     

Effects of same-modality interference on immediate serial recall of auditory and visual information.

Two studies investigated the effects of same-modality interference on the immediate serial recall of auditorily and visually presented stimuli. Typically, research in which this task is used has been conducted in quiet rooms, excluding auditory information that is extraneous to the auditorily presented stimuli. However, visual information such as background items clearly within the subject's view have not been excluded during visual presentation. Therefore, in both the present studies, the authors used procedures that eliminated extra-list visual interference and introduced extra-list auditory interference. When same-modality interference was eliminated, weak visual recency effects were found, but they were smaller than those that were generated by auditorily presented items. Further, mid-list and end-of-list recall of visually presented stimuli was unaffected by the amount of interfering visual information. On the other hand, the introduction of auditory interference increased mid-list recall of auditory stimuli. The results of Experiment 2 showed that the mid-list effect occurred with a moderate, but not with a minimal or maximal, level of auditory interference, indicating that moderate amounts of auditory interference had an alerting effect that is not present in typical visual interference.     

Effect of locus of warning tone on auditory choice reaction time

Forty Ss pressed a left- or right-hand key depending on the ear in which they heard a 500-Hz stimulus tone. Half of the Ss were instructed to press the key on the same side as the ear stimulated (corresponding condition), while the other half pressed the key on the opposite side (noncorresponding condition). A 200-Hz warning tone preceded the stimulus tone by either 200 or 400 msec. The warning tone was presented to the left ear, the right ear, or to both ears in a predetermined random sequence. The locus of the warning tone affected RT on noncorresponding trials but not on corresponding trials. The effect consisted of a significant slowing of information processing on trials where the warning tone was contralateral to the response. Results were explained in terms of an initial tendency to respond toward the source of the warning tone.     

Effects of serial position and set size in auditory recognition memory

Auditorially presented lists of from one to six digits were memorized by Ss with instructions to scan the memory set to determine the presen’ce or absence of a single auditorially presented probe digit. Results showed cooccurrence of parallel linear increases in decision time with list length for positive and negative responses and effects of serial position of probes in the memory lists. A comparison with two previous studies using visual presentation of materials suggests faster encoding of auditorially presented probes but similarity in processing time in memory once probes have been encoded.     

Facilitation of auditory word recognition

An experiment that investigated facilitation of recognition of spoken words presented in noise IS described, Prior to the test session, the subjects either read words or heard them spoken in one of two. voices while making a semantic judgment upon them. There was a large effect of auditory priming on word recognition that did not depend upon the voice (male or female) of presentation, There were much smaller, but significant, effects of prior visual experience of the words. The implications of these data for the logogen model are discussed.     

Stimulus-response compatibility affects auditory Stroop interference

The contribution of stimulus-response compatibility to Stroop interference was tested in an auditory version of the Stroop test. The words “high” and “low” were presented in high and low pitches with either the pitch or the word designated as the relevant dimension. College students categorized the relevant stimulus dimension with a verbal response, a buttonpress, or a pitched hum. Significant interference occurred in the incompatible conditions (pitch-verbal, word-hum, pitch-button), but not in the compatible conditions (pitch-hum, word-verbal, word-button). The results indicated that stimulus-response compatibility was an important determinant of observed interference. It was suggested that stimulus-response incompatibility contributed to the response competition that presumably occurs in Stroop tasks.     

Things are sounding up: Affective influences on auditory tone perception

Recent studies have documented robust and intriguing associations between affect and performance in cognitive tasks. The present two experiments sought to extend this line of work with reference to potential cross-modal effects. Specifically, the present studies examined whether word evaluations would bias subsequent judgments of low- and high-pitch tones. Because affective metaphors and related associations consistently indicate that positive is high and negative is low, we predicted and found that positive evaluations biased tone judgment in the direction of high-pitch tones, whereas the opposite was true of negative evaluations. Effects were found on accuracy rates, response biases, and reaction times. These effects occurred despite the irrelevance of prime evaluations to the tone judgment task. In addition to clarifying the nature of these cross-modal associations, the present results further the idea that affective evaluations exert large effects on perceptual judgments related to verticality.     

Effects of social influence in a recognition task of auditory intensity: a temporary shift in criterion.

The effects of responses of another person or a computer occurring prior to the subjects' responses in tasks to recognition model which assumed that subjects shifted their decision criteria temporarily on each trial. A parameter representing the amount of criterion shift reliably estimated sensitivity to social influence. When the social sensitivity parameter was estimated from the data, discriminative ability, defined as d', was unaffected by the presence of social influence. Principal components analyses suggested that social sensitivity and discriminative ability represented essentially orthogonal components of subjects' decision behavior.     

Effects of length,tonal structure,and contour in the recognition of tone series

Four experiments on recognition of tone series are reported. The first experiment tested the accuracy of recognition in relation to length, contour complexity, and tonal structure of the series. Series comprised (1) 7 or 10 tones, (2) either a strong or a weak tonal structure, depending on the temporal ordering of the tones, and (3) few or many contour reversals. The second experiment used 7-tone series having either a strong or a weak tonal structure, depending on the mode (Ionian or Phrygian) in which the series was presented. Both experiments employed asamedifferent task in which a standard series was compared with either an exact or an inexact transposition, the latter type having one incorrectly transposed tone (mostly nondiatonic in Experiment 1 and always diatonic in Experiment 2) These experiments showed that (1) 7-tone series were better recognized than were 10-tone series, (2) series with a strong tonal structure were better recognized than were series with a weak tonal structure, and (3) contour complexity did not influence the responses. Two control experiments, using mistuned tone series, showed that the outcomes of Experiments 1 and 2 could not be attributed to nonmusical artifacts of the stimulus set.     

Human central auditory plasticity associated with tone sequence learning

We investigated learning-related changes in amplitude, scalp topography, and source localization of the mismatch negativity (MMN), a neurophysiological response correlated with auditory discrimination ability. Participants (n = 32) underwent two EEG recordings while they watched silent films and ignored auditory stimuli. Stimuli were a standard (probability = 85%) and two deviant (probability = 7.5% each for high [HD] and low [LD]) eight-tone sequences that differed in the frequency of one tone. Between recordings, subjects practiced discriminating the HD or LD from the standard for 6 min. The amplitude of the LD MMN increased significantly across recordings in both groups, whereas the amplitude of the HD MMN did not. The LD was easier to discriminate than was the HD. Thus, practicing either discrimination increased the MMN for the easier discrimination. Learning and changes in the LD MMN amplitude were highly correlated. Source localizations of event-related potentials (ERPs) to all stimuli revealed bilateral sources in superior temporal regions. Compared with the standard ERP, the LD ERP revealed a stronger source in the left superior temporal region in both recordings, whereas the right-sided source became stronger after learning. Consistent with prior studies of auditory plasticity in animals and humans, tone sequence learning induced rapid neurophysiological plasticity in the human central auditory system. The results also suggest that there is asymmetric hemispheric involvement in tone sequence discrimination learning and that discrimination difficulty influences the time course of learning-related neurophysiological changes.     

Detection and recognition of auditory patterns

The detection/recognition theorem (Starr, Metz, Lusted, & Goodenough, 1975) provides a signal detection theory prediction of an observer's ability to identify one of a set of possible signals on the basis of the observer's ability to detect whether any signal is presented. The present findings show that the theorem can be applied to complex auditory stimuli in a fashion that is not merely a trivial extension of the results obtained with simple auditory stimuli.     

Temporal interference effects in auditory amplitude discrimination

The efficiency, y,η of performance in amplitude discrimination is examined as a function of the temporal separation, Γ, of the two signals to be discriminated. Performance in a monaural amplitude discrimination task is compared with that in a dichotic amplitude discrimination task, in which the first of the two signals was always presented to one ear and the second signal to the other ear. The difference in the shape of the resulting η versus Γ functions for the monaural and dichotic cases is interpreted in terms of peripheral and central interference effects.