Jeremy R. Gaston

Auditory event perception: The source—perception loop for posture in human gait

There is a small but growing literature on the perception of natural acoustic events, but few attempts have been made to investigate complex sounds not systematically controlled within a laboratory setting. The present study investigates listeners’ ability to make judgments about the posture (upright—stooped) of the walker who generated acoustic stimuli contrasted on each trial. We use a comprehensive three-stage approach to event perception, in which we develop a solid understanding of the source event and its sound properties, as well as the relationships between these two event stages. Developing this understanding helps both to identify the limitations of common statistical procedures and to develop effective new procedures for investigating not only the two information stages above, but also the decision strategies employed by listeners in making source judgments from sound. The result is a comprehensive, ultimately logical, but not necessarily expected picture of both the source—sound—perception loop and the utility of alternative research tools.

Did you hear that? The role of stimulus similarity and uncertainty in auditory change deafness.

Change deafness, the auditory analog to change blindness, occurs when salient, and behaviorally relevant changes to sound sources are missed. Missing significant changes in the environment can have serious consequences, however, this effect, has remained little more than a lab phenomenon and a party trick. It is only recently that researchers have begun to explore the nature of these profound errors in change perception. Despite a wealth of examples of the change blindness phenomenon, work on change deafness remains fairly limited. The purpose of the current paper is to review the state of the literature on change deafness and propose an explanation of change deafness that relies on factors related to stimulus information rather than attentional or memory limits. To achieve this, work on across several auditory research domains, including environmental sound classification, informational masking, and change deafness are synthesized to present a unified perspective on the perception of change errors in complex, dynamic sound environments. We hope to extend previous research by describing how it may be possible to predict specific patters of change perception errors based on varying degrees of similarity in stimulus features and uncertainty about which stimuli and features are important for a given perceptual decision.

Listener perception of single-shot small arms fire

The ability to identify and interpret impulse sounds from small arms weaponsfire is a very important element of a soldier’s situational awareness that is criti-cally needed to avoid potential danger. For example, differentiation of hostilefrom friendly weapons fire can indicate the need for increased vigilance andcanrevealtheapproximatelocationofanenemyelement.Inaddition,estimationofweaponsizecanbeusedtoinfertheresourcesofanenemyelement.Despitethepotential operational importance of these sounds, little is known about listenerperception of impulse weapons sounds. The present work investigates listenerability to differentiate signatures of various small arms weapons on the basis ofhigh-quality recordings of single-shot impulse sounds. Experiment 1 measuredlistener perceived similarity for paired small arms impulse sounds. A multi-dimensional scaling solution (MDS) based on listener ratings showed significantoverlap in perceptual space for most rifle sounds, but the mappings of handgunsounds were largely segregated from all rifle sounds. These mappings corre-lated well with measured source and sound properties of the small arms weap-ons. Experiment 2 measured discrimination performance for selected sets ofcontrasted weapon pairings. In general, discrimination performance correlatedwell with the listener perceptual space measured in Experiment 1, with bestperformance for handgun-rifle pairings and worst performance for rifle-riflepairings.

Backward recognition masking as a general type of interference in needed poststimulus processing

Auditory backward recognition masking (ABRM) has been argued to reflect interference in the storage and/or processing of a short-lived sensory form of information and has been viewed as a relatively invariant attribute of auditory pitch processing for very brief stimuli that are minimally separated in frequency (ΔF). In contrast, the present study demonstrates that ABRM reflects interference with several basic principles of auditory processing. Measured in terms of target tone duration, rather than ΔF, ABRM is demonstrated for target stimuli representing the interval of a musical fifth and masker—target stimulus intervals of a musical third, with thresholds ranging from approximately 22 to 55 msec and psychometric functions that are indicative of more than one contributing factor. On the basis of common underlying principles, the possibility that the threshold for the identification of temporal order of onset reflects ABRM and possible implications for the perception of complex stimuli, including speech, are discussed.

A three‐stage approach to understanding listener perception of weapon signature for small arms.

The ability to identify and interpret impulse sounds from small arms weapon fire is a very important element of soldier’s situational awareness that is critically needed to avoid potential danger. For example, differentiation of hostile from friendly weapon fire can indicate the need for increased vigilance and can reveal the approximate location of an enemy element. In addition, estimation of weapon size can be used to infer the resources of an enemy element. Despite the potential operational importance of these sounds, little is known about listener perception of impulse weapon sounds. The present work investigates listener ability to differentiate signatures of various small arms based on high‐quality recordings of single‐shot impulse sounds. Following the three‐stage approach developed by Pastore et al. (2008) for studying natural sound perception, the interrelationships between weapon source properties, the physical attributes of the sounds produced and listener perception are evaluated for a number ...

Evaluation and modification of listener decision strategy in human gait perception

Beyond obvious differences, there are many similarities in the challenges faced in studies of speech and natural (nonspeech) sounds. The source events are dynamic, complex and highly variable. Source properties map only statistically in the sounds produced, resulting in many acoustic properties that are only sometimes accurate indicators of specific source properties. Finally, beyond the nonlinear mapping of acoustic to perceptual properties, listeners vary in decision weights assigned to the perceived attributes of the sounds. Beginning with this complex conceptualization of source‐sound‐perception relationships, our research on the perception of human gait from walking sounds investigated the perception of walker posture. The current research extends this project on human gait perception, evaluating both the decision strategy of listener individual listeners and alternative approaches to improving that decision strategy. Implications for studying of both natural nonspeech and speech will be briefly disc...

The relationship between perceived pleasantness and memory for environmental sounds

The everyday auditory environment contains many sounds that can be influenced by semantic information and listener experiences. Some sounds are more memorable than others and there is limited work examining the role of specific semantic or subjective attributes on retrieval success for environmental sounds. The present study examines the relationship between pleasantness ratings and memory performance on a cued-recall task. A group of listeners were presented with 36 environmental sounds and asked to rate each for perceived pleasantness to provide baseline evaluations for each sound. Based on the ratings, stimuli were sorted into two pleasantness-balanced groups. A second group of listeners evaluated half of the stimuli for pleasantness during the “study” phase, which was followed by a cued recall test. At test, half of the items were “old” (from the study phase), and half were “new” (from the set of 36 sounds). The results demonstrate that listener’s recalled more pleasant sounds more accurately than unp...

Sound source similarity influences change perception in complex scenes

Everyday listening involves identifying an ever-changing milieu of sound sources in the environment. Recent studies have demonstrated that change perception during complex listening tasks is highly error prone; errors can exceed 30% for sounds that are clearly detectable and identifiable in isolation. This change deafness has been generally attributed to failures of attention or memory. The current study investigates the possibility that lower-level informational effects such as acoustic or semantic similarity are predictive of change deafness. In experiment 1, listeners rated pairs of sounds for their overall similarity. These ratings were later used in experiments 2 and 3 to evaluate the effect of similarity on performance. In experiments 2 and 3, listeners were briefly presented with pairs of auditory scenes. In experiment 2 listeners were asked to identify if a change in a sound source occurred, and in experiment 3, listeners were asked to indicate where a change occurred across an array of loudspeake...

Sound source similarity influences change perception during complex scene perception

Everyday listening involves identifying an ever-changing milieu of sound sources in the environment. Recent studies have demonstrated that change perception during complex listening tasks is highly error prone; errors can exceed 30% for sounds that are clearly detectable and identifiable in isolation. This change deafness has been generally attributed to failures of attention or memory. The current study investigates the possibility that lower-level informational effects such as acoustic or semantic similarity are predictive of change perception errors. Listeners were briefly presented with pairs of auditory scenes. In experiment 1, the listeners’ were asked to identify if a change in sound source occurred. In experiment 2, listeners were asked to indicate where a change occurred across an array of loudspeakers. Results indicate that performance on the change identification and localization task was strongly influenced by the degree of similarity between the changed source and the “background” sources. Fu...

Auditory localization performance in the azimuth for tactical communication and protection systems

An important consideration in assessing auditory abilities is the effect personal protective equipment (PPE) can have on performance. Tactical Communication and Protection (TCAP) systems are a type of PPE that is becoming more common in military applications. These types of systems provide radio communications, while also protecting the user from hazardous noise through passive and active attenuation. These systems have an active acoustic pass-through mechanism that utilizes an external microphone and internal earphone to restore environmental hearing. Past research has shown that this type of pass-through mechanism can negatively affect localization ability. In the present study, six participants localization ability was tested for two different signals (AK-47 impulse, 500 ms white noise) across an array of eight loudspeakers arranged in a ring around the test participant. The systems tested consisted of three types of in-ear TCAPs, one over-the-ear TCAPs, and one passive nonlinear hearing protection dev...