Abstract: A deviation in the acoustic environment activates an automatic change-detection system based on a memory mechanism that builds a neural trace representing the preceding sounds. The present study revealed that the auditory-cortex mechanisms underlying this sensory memory integrate acoustic events over time, producing a perception of a unitary auditory event. We recorded magnetic responses (MMNm) to occasional stimulus omissions in trains of stimuli presented at a constant stimulus-onset asynchrony (SOA) that was, in different blocks, either shorter or longer in duration than the assumed length of the temporal window of integration. A definite MMNm was elicited by stimulus omission only with the three shortest SOAs used: 100, 125, and 150 ms, but not with 175 ms. Thus, 160-170 ms was estimated as the length of the temporal window used by the central auditory system in integrating successive auditory input into auditory event percepts.

Abstract: A number of sex differences have been documented in the human auditory system. Females as a group have greater hearing sensitivity, greater susceptibility to noise exposure at high frequencies, shorter latencies in their auditory brain‐stem responses, more spontaneous otoacoustic emissions (SOAEs), and stronger click‐evoked otoacoustic emissions than males as a group. Males are better at sound localization, detecting binaural beats, and detecting signals in complex masking tasks than are females. During the first half of the menstrual cycle, several aspects of female hearing move in the male direction. The sex difference normally present in SOAEs is absent in females from opposite‐sex twin pairs. The implication is that their auditory systems have been masculinized prenatally by exposure to high levels of androgens produced by their male cotwins, analogous to an effect well established in other mammals. This suggests that some of the other sex differences in hearing are also attributable to differences in...

Abstract: It is currently controversial whether auditory events produce inhibition of return (IOR). Although some authors argue that this can arise, others propose that peripheral auditory cues do not produce the characteristic IOR pattern of delayed detection latencies for ipsilaterally presented auditory or visual targets, unless a saccade is made to the cued location. We suggest that these previous discrepancies may depend on whether attention is reoriented centrally following the peripheral sound. We presented spatially uninformative peripheral auditory cues prior to visual targets requiring speeded detection responses. IOR was found in the absence of eye movements, provided an auditory reorienting event was presented at central fixation between onset of the peripheral cue and the subsequent target, but not when the central reorienting event was visual. A subsequent experiment demonstrated that auditory IOR between successive targets is similarly significantly reduced in the absence of an appropriate central reorienting event. These results imply that auditory stimuli can induce IOR directly. Previous failures to demonstrate IOR following auditory cues may have been due to an opposing influence of long-lasting attentional facilitation at the cued location, rather than to the putative inability of auditory stimuli to engage oculomotor processes generating IOR.

Abstract: The cochlea is the window through which the central auditory system views its acoustic environment. The transduction of air borne sound by the hair cells and the neural encoding at the periphery place constraints on the acoustic features that are available for further processing by auditory neurons in the brain. At birth, the cochlea in most altricial mammals is still very immature. It is effectively unresponsive to sound and generates little sustained (spontaneous) activity. During the first month after the onset of hearing, significant changes occur in cochlear functioning, changes that are reflected in both the overall level and spatiotemporal pattern of nerve impulses that are transmitted centrally over the auditory nerve. The task of determining the extent to which maturational changes in auditory perception, spontaneous activity, and central responses to sound originate within the cochlea and to what degree these changes reflect the development of central synaptic processes remains a formidable challenge.

Abstract: : The quality of realism in virtual environments is typically considered to be a function of visual and audio fidelity mutually exclusive of each other. However, the virtual environment participant, being human, is multi-modal by nature. Therefore, in order to more accurately validate the levels of auditory and visual fidelity required in a virtual environment, a better understanding is needed of the intersensory or cross modal effects between the auditory and visual sense modalities. To identify whether any pertinent auditory visual cross modal perception phenomena exist, 108 subjects participated in three main experiments which were completely automated using HTML, Java, and JavaScript computer programming languages. Visual and auditory display quality perception were measured intramodally and intermodally by manipulating visual display pixel resolution and Gaussian white noise level and by manipulating auditory display sampling frequency and Gaussian white noise level. Statistically significant results indicate that: (1) medium or high quality auditory displays coupled with high quality visual displays increase the quality perception of the visual displays relative to the evaluation of the visual display alone, and (2) low quality auditory displays coupled with high quality visual displays decrease the quality perception of the auditory displays relative to the evaluation of the auditory display alone. These findings strongly suggest that the quality of realism in virtual environments must be a function of both auditory and visual display fidelities inclusive of each other.

Abstract: After preliminary computerized training on visual-visual identity matching, a 5-year-old boy with autism (Sam) was given visual-visual and auditory-visual matching-to-sample tests with new stimuli. He did well in matching dictated name samples to 20 pictures, 26 printed upper case letters, and 9 single-digit numbers. In matching the visual stimuli (pictures, letters, or numbers) to themselves, however, he did not perform well. We then increased the number of picture comparisons per trial from two to three. In tests after this three-comparison training, Sam correctly matched on 95% of the original 20-stimulus, four-comparison, identity-matching test trials. He went on to demonstrate accurate identity matching of the numbers, letters, and new pictures. In identity-matching tests on the table top, he performed poorly until the stimulus array was made to resemble the stimulus arrangement on the computer. These findings showed that seemingly small procedural changes can influence performance and demonstrated that successful auditory-visual matching does not guarantee proficiency in visual-visual identity matching.

Abstract: The range of acoustic features that are encoded and interpreted by the mature central auditory system has become a rapidly expanding topic of research (Bregman 1990; Handel 1990; Yost 1991). However, our understanding of the developmental processes that underlie auditory perception remains rudimentary. This chapter focuses on developmental mechanisms that contribute to central auditory processing of acoustic stimuli. The term processing will refer to the neural mechanisms by which the central auditory system represents acoustic information. In principle, this representation may take the form of a single neuron’s discharge pattern or the activity pattern of an entire central auditory structure.

Abstract: Conscious sensory perception and its modulation by volition are integral to human mental life. Functional neuroimaging techniques provide a direct means of identifying and characterizing in vivo th...

Abstract: The selective nature of human perception and action implies a modulatory interaction between sensorimotor processes and attentional processes. This paper explores the use of functional imaging in humans to explore the mechanisms of perceptual selection and the fate of irrelevant stimuli that are not selected. Experiments with positron emission tomography show that two qualitatively different patterns of modulation of cerebral blood flow can be observed in experiments where non-spatial visual attention and auditory attention are manipulated. These patterns of modulation of cerebral blood flow modulation can be described as gain control and bias signal mechanisms. In visual and auditory cortex, the dominant change in cerebral blood flow associated with attention to either modality is related to a bias signal. The relation of these patterns of modulation to attentional effects that have been observed in single neurons is discussed. The existence of mechanisms for selective perception raises the more general question of whether irrelevant ignored stimuli are nevertheless perceived. Lavie's theory of attention proposes that the degree to which ignored stimuli are processed varies depending on the perceptual load of the current task. Evidence from behavioural and functional magnetic resonance imaging studies of ignored visual motion processing is presented in support of this proposal.

Abstract: The relatonship between the intrinsic properties of sounds and how we hear them is often misunderstood. This article focuses on the relation between loudness and intensity; the concepts of pitch and timbre are dealt with in the following paper.

Abstract: This study presents a new auditory-based distance measure with application to concatenative speech synthesis. This measure employs the Carney auditory model to produce a feature vector related to auditory perception. For concatenative synthesis, the new measure is employed to assess perceived discontinuities at segment transitions. Evaluations using a restricted data base environment show that the new measure can be effective in improving speech synthesis performance.

Abstract: Music and information appear to be processed by means of the phonological loop, as opposed to the visuospatial sketchpad, in working memory. Is this also true of memory for nonverbal, nonmusical auditory images, such as the characteristic sounds made by objects? In the present study, university students were presented with equivalent verbal stimuli, nonsemantic auditory stimuli, or pictorial stimuli, by category or in random order. Significant category superiority effects (CSEs) were obtained for both verbal and auditory stimuli, but not for pictorial stimuli, consistent with the expectation of phonological loop processing. However, absolute levels of recall for auditory stimuli were significantly higher than for verbal stimuli and did not differ from the levels observed for pictures, suggesting a somewhat intermediate character of processing for nonverbal, nonmusical auditory information.

Abstract: The preceding paper discussed the difficulties in teaching various concepts in sound. This article extends the discussion to the concepts of pitch and timbre.

Abstract: This simulator-based study examined the use of conventional auditory warnings (tonal, non-verbal sounds) and auditory icons (representational, non-verbal sounds), alone and in combination with a dash-mounted visual display to warn commercial motor vehicle operators of impending front-to-rear and side collision situations. Driver performance was measured in the simulated driving task via brake response time in the front-to-rear collision scenarios and via a count of accident occurrence in the side collision scenarios. For both front-to-rear and side collision scenarios, auditory icons elicited significantly improved driver performance over conventional auditory warnings. Driver performance improved when collision warning information was presented through multiple modalities.

Abstract: Much of our present understanding of sensory processing by the human brain is obtained from studies of patients with sensory impairments. Past auditory studies have focused strongly on the peripheral mechanisms of hearing disorders, and have led to an overuse of stimuli that are good for testing the transfer functions of simple acoustic features but are not suitable for understanding the perception of complex auditory stimuli or stimulus sequences. Magnetoencephalography (MEG) is a non-invasive method for studying how the human brain processes and stores auditory information. The long-term groundwork in building up the basic understanding of cortical dynamics during various "simple" stimulations now allows the use of more complex, real-life-like stimuli, and clinical applications.

Abstract: Functional Magnetic Resonance Imaging (fMRI) holds exciting potential as a research and clinical tool for exploring the human auditory system. This noninvasive technique allows the measurement of d...

Abstract: The influence of visual information on auditory speech perception can be observed under conditions where the two sources of information are discrepant [McGurk and MacDonald (1976)]. Recent studies from our laboratory [Hall et al. (1996)] focused on one such condition, where a face producing /b/ is combined with a dubbed auditory /g/ token, resulting in the frequent auditory perception of /bg/. These studies used auditory tokens that varied in quality, and have suggested that the probability of auditory consonant identification as /g/ was sufficient to predict the probability of /bg/ responses. The current study extended this approach to the converse conditions, where an auditory /b/ was dubbed on a visual /g/ production, which typically results in the frequent auditory perception of /d/ or /th/. Additionally, similarity ratings were collected for sets of auditory /g/ and /b/ stimuli, as well as for both types of auditory‐visual conditions (/g/+/b/ and /b/+/g/). Multidimensional scaling (MDS) of these ratings was used to determine whether auditory category structure predicts MDS solutions for combined auditory and visual information. Implications of the results for the nature of auditory‐visual speech integration will be discussed. [Work supported by NICHD.]

Abstract: It is a continual challenge for clinical audiologists to obtain valid and reliable information concerning the auditory sensitivity and auditory processing abilities of young children, especially those with language disorders. The majority of the tests that are available for use with young children do not provide much information regarding the problems they are likely to encounter in typical communication situations. This paper describes a new “class” of auditory tests designed to evaluate the ability of young children to (1) detect commonly encountered sounds, (2) localize sound sources, and (3) understand speech in noise. These tests appear to be sensitive to the effects of auditory pathology and to the normal development of auditory processing skills.

Abstract: Event-related potentials (ERPs) evoked by light flashes and auditory tones in a standard odd-ball procedure were recorded from Fz, Cz and Pz scalp sites. Tonic pain was evoked by immersion of the hand in cold water (5 degrees C). Significant effects of pain were found in responses to target stimuli but not in responses to non-target stimuli. P300 wave was affected more than the earlier P200 component. The reduction of P300 amplitude was the strongest effect, both in auditory and visual tests. P300 latency was not significantly affected. Difference curves (target minus non-target ERPs) showed the additional effects: latency of P200 component was elongated and its amplitude enlarged but only in auditory experiments. In control experiments with warm water stimulation no significant alterations of P300 or P200 components were found. The results show that the effect of tonic pain is specific: it predominantly affects the processes that manifest themselves as amplitude changes of P300 components in responses to target stimuli.

Abstract: This study examines the accuracy of judgements of relative distance of traffic sounds (car and lorry) compared with nonattributed sounds (white noise). Adults judged whether sounds were comparatively nearer or further away in both conditions when decibel levels were the same and when decibel levels differed. Results indicated that judgement of relative distance is generally difficult and that such judgements are not based on loudness alone, particularly for traffic sounds. More errors were made when decibel levels were the same, indicating a reluctance to rely on loudness as an indicator of distance. Also more errors were made for traffic sounds. It was suggested that nonauditory criteria may be used in interpreting sounds, possibly including past experience and visual imagery. Finally, the implications of the results for road safety are discussed.

Abstract: In the last few years, Functional Magnetic Resonance Imaging (fMRI) has been widely accepted as an effective tool for mapping brain activities in both the neurosensorial and the cognitive field. The present work aims to assess the possibility of using fMRI methods to perform a non-invasive evaluation of the human auditory function. To this end the cortical response to different non speech stimuli (pure tones, pulsed tones) was examined for ten subjects with no audiological impairment. Our findings point out some remarkable differences in both the spatial and the temporal features of the primary auditory cortex response to pulsed tones and to pure tones.

Abstract: He may not say it, even to himself, but that is often how a child with auditory perceptual difficulties feels when he is asked to listen and learn in the classroom. He can probably hear sounds perfectly well, but he can't interpret their meaning. Although his peripheral hearing mechanism functions adequately, his brain does not accurately process auditory messages. Somewhere in the brain's pathways auditory information is garbled, delayed, or blocked. Because the incoming information is confused, the resulting interpretation is also confused.

Abstract: While non-stationary stochastic modeling techniques and the exponential growth of computational resources have led to substantial improvements in vocabulary size and speaker independence, most automatic speech recognition (ASR) systems remain overly sensitive to the acoustic environment, precluding widespread applications. The human auditory system, speech production mechanisms, and languages, on the other hand, are extremely well-tuned to facilitate speech communication in noise. Better modeling of these systems and mechanisms should illuminate robust strategies for speech processing applications. In this work, models of temporal adaptation, spectral peak isolation, an explicit parameterization of the position and motion of local spectral peaks, and the perception of pitch-rate amplitude modulation cues are shown to reduce the error rate of a word recognition system in noise by more than a factor of 4 over the typical current processing.

Abstract: The principles of time-frequency or time-scale analysis have been applied to study the processing of the human auditory system, which is often modeled as a bank of bandpass overlapping nonlinear filters. While a bandpass nonlinear model is an accurate portrayal of the physiological properties of the peripheral auditory system, and aspects of such organization have been shown to persist throughout the central auditory system, the "natural axes" of the human auditory perception appear to be time and pitch, rather than time and frequency or scale. Furthermore, "pitch" appears to have at least two perceptual attributes, chroma and tone height. We develop several mathematical structures for time-chroma and time-tone-height representations of acoustic signals and study, in particular, how these structures represent harmonic signals.