Identification Of Environmental Sounds Research Articles

Scalable identification of mixed environmental sounds, recorded from heterogeneous sources

Sound events can be used to establish context to assist a user to perform context-dependent tasks. The state of the art methods allow the identification of isolated sound events, even with background noise when it can be modeled, however for mixed sound recognition the challenge still stands. The problem consist in identifying all the sounds occurring in a stream. In this paper we propose an audio representation suitable for mixed sounds identification without background/foreground modeling. Our approach is also lightweight, both in computational and space complexity and the final representation does not depend on the length of the input sound. We extract spectral, band-split, frame level features and their first and second derivatives in each band. The final representation is a set of histograms, one for each band. We proved experimentally that this representation is robust and allows the identification of overlapped sound events. We compared our approach against a representation based on the Mel Frequency Cepstral Coefficients and Non Negative Matrix Factorization for blind source separation using a single microphone, this was the only approach comparable to ours. For testing we conducted two different set of experiments. In the first one we collected poor quality audio recordings using a low-end smartphone for training. Without further enhancing or processing we were able to identify the components of classes of sound mixtures, even with sounds downloaded from the Internet where we had no control on the recording conditions or the foreground noise. In the second set of experiments we recorded 15 challenging sound classes of similar spectrum, from an application scenario and identified them in a continuous recording with three types of background noise. Our results outperform the state of the art in speed, precision and recall.

Identification of environmental sounds and melodies in syndromes of anterior temporal lobe degeneration

Recognition of nonverbal sounds in semantic dementia and other syndromes of anterior temporal lobe degeneration may determine clinical symptoms and help to define phenotypic profiles. However, nonverbal auditory semantic function has not been widely studied in these syndromes. Here we investigated semantic processing in two key nonverbal auditory domains – environmental sounds and melodies – in patients with semantic dementia (SD group; n=9) and in patients with anterior temporal lobe atrophy presenting with behavioural decline (TL group; n=7, including four cases with MAPT mutations) in relation to healthy older controls (n=20). We assessed auditory semantic performance in each domain using novel, uniform within-modality neuropsychological procedures that determined sound identification based on semantic classification of sound pairs. Both the SD and TL groups showed comparable overall impairments of environmental sound and melody identification; individual patients generally showed superior identification of environmental sounds than melodies, however relative sparing of melody over environmental sound identification also occurred in both groups. Our findings suggest that nonverbal auditory semantic impairment is a common feature of neurodegenerative syndromes with anterior temporal lobe atrophy. However, the profile of auditory domain involvement varies substantially between individuals.

The effect of experience on environmental sound identification

The perception of environmental stimuli was compared across normal hearing (NH) listeners exposed to an eight-channel sinewave vocoder and experienced bilateral, unilateral, and bimodal cochlear implant (CI) users. Three groups of NH listeners underwent no training (control), one day of training with environmental stimuli (exposure), or four days of training with a variety of speech and environmental stimuli (experimental). A significant effect of training was observed. The experimental group performed significantly better than exposure or control groups, equal to bilateral CI users, but worse than bimodal users. Participants were divided into low, medium and high-performing groups using a two-step cluster algorithm. High-performing members were only observed for the CI and experimental conditions, and significantly more low-performing members were observed for exposure and control conditions, demonstrating the effectiveness of training. A detailed item-analysis revealed that the most accurately identified sounds were often temporal in nature or contained iconic repeating patterns (e.g., a horse galloping). Easily identified stimuli were common across all groups, with experimental subjects identifying more short or spectrally driven stimuli, and CI users identifying more animal vocalizations. These data demonstrate that explicit training in identifying environmental stimuli improves sound perception, and could be beneficial for new CI users.

IDENTIFICATION OF ENVIRONMENTAL SOUNDS AND MELODIES IN SYNDROMES OF ANTERIOR TEMPORAL LOBE DEGENERATION

article i nfo Recognition of nonverbal sounds in semantic dementia and other syndromes of anterior temporal lobe degener- ation may determine clinical symptoms and help to define phenotypic profiles. However, nonverbal auditory semantic function has not been widely studied in these syndromes. Here we investigated semantic processing in two key nonverbal auditory domains - environmental sounds and melodies - in patients with semantic dementia (SD group; n = 9) and in patients with anterior temporal lobe atrophy presenting with behavioural decline (TL group; n = 7, including four cases with MAPT mutations) in relation to healthy older controls (n = 20). We assessed auditory semantic performance in each domain using novel, uniform within-modality neuropsychological procedures that determined sound identification based on semantic classification of sound pairs. Both the SD and TL groups showed comparable overall impairments of environmental sound and melody identification; individual patients generally showed superior identification of environmental sounds than melodies, however relative sparing of melody over environmental sound identification also occurred in both groups. Our findings suggest that nonverbal auditory semantic impairment is a common feature of neurodegen- erative syndromes with anterior temporal lobe atrophy. However, the profile of auditory domain involvement varies substantially between individuals. © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license

Signal Processing Methods for Improvement of Environmental Perception of Persons with Deafblindness

Environmental perception is a functional area that is severely limited in persons with deafblindness (DB) who belong a category of people with severe disabilities. Monitor is a vibratory aid developed with the aim to improve environmental perception of persons with DB. The aid consists of a mobile phone with an application connected to a microphone and vibrator. Monitor picks up the sounds produced by events by microphone, processes the sound using an algorithm programmed as an application in the mobile phone and then presents the signal via the vibrator to the persons with DB to be sensed and interpreted. In previous laboratory studies, four algorithms (AM, AMMC, TR, and TRHA) were developed based on modulating, and transposing principles. The algorithms were tested by persons with normal hearing/hearing impairment and selected as good candidates to improve vibratory identification of environmental sounds. In this on-going the algorithms are tested by 13 persons with congenital D and five persons with DB using Monitor in a realistic environment, living room, kitchen or office. Forty five recorded environmental sounds were used as test stimuli. The subjects tested the algorithms two times, Test and Retest each including a test session initiated by a training session. The four algorithms were tested in four days at Test and four days at Retest in total eight test days. Each test day began with a training session where a sound was presented as vibrations to be sensed by the person with the aim to remember its pattern and identity. The 45 sounds were grouped in four groups where an specific algorithm was chosen to process an specific sound group in a specific day. At the test session a sound was presented and the person was given 5 randomly chosen sound alternatives to choose the one as represented sound. The algorithms were different for different sound groups during four different test days so all algorithms were used to process all sounds. The algorithms were tested a second time, Retest, in same way as in Test. The mean value of identification of environmental sounds varied between 74.6% and 84.0% at Test and between 86.9% and 90.4% at Retest. The identification results at Retest were significantly improved (p<0.01) for all algorithms after a relatively short time of training indicating a good learning effect. At Test the algorithm AM was significantly better than the algorithms AMMC and TRHA (p< 0.01) and the algorithm TR was better than TRHA (p<0.01). The algorithms AM, AMMC, and TR were selected as good candidates to be implemented in the Monitor to improve environmental perception.

Right cerebral hemisphere and central auditory processing in children with developmental dyslexia

We hypothesized that if the right hemisphere auditory processing abilities can be altered in children with developmental dyslexia (DD), we can detect dysfunction using specific tests. We performed an analytical comparative cross-sectional study. We studied 20 right-handed children with DD and 20 healthy right-handed control subjects (CS). Children in both groups were age, gender, and school-grade matched. Focusing on the right hemisphere's contribution, we utilized tests to measure alterations in central auditory processing (CAP), such as determination of frequency patterns; sound duration; music pitch recognition; and identification of environmental sounds. We compared results among the two groups. Children with DD showed lower performance than CS in all CAP subtests, including those that preferentially engaged the cerebral right hemisphere. Our data suggests a significant contribution of the right hemisphere in alterations of CAP in children with DD. Thus, right hemisphere CAP must be considered for examination and rehabilitation of children with DD.

Agnosia for accents in primary progressive aphasia

As an example of complex auditory signal processing, the analysis of accented speech is potentially vulnerable in the progressive aphasias. However, the brain basis of accent processing and the effects of neurodegenerative disease on this processing are not well understood. Here we undertook a detailed neuropsychological study of a patient, AA with progressive nonfluent aphasia, in whom agnosia for accents was a prominent clinical feature. We designed a battery to assess AA's ability to process accents in relation to other complex auditory signals. AA's performance was compared with a cohort of 12 healthy age and gender matched control participants and with a second patient, PA, who had semantic dementia with phonagnosia and prosopagnosia but no reported difficulties with accent processing. Relative to healthy controls, the patients showed distinct profiles of accent agnosia. AA showed markedly impaired ability to distinguish change in an individual's accent despite being able to discriminate phonemes and voices (apperceptive accent agnosia); and in addition, a severe deficit of accent identification. In contrast, PA was able to perceive changes in accents, phonemes and voices normally, but showed a relatively mild deficit of accent identification (associative accent agnosia). Both patients showed deficits of voice and environmental sound identification, however PA showed an additional deficit of face identification whereas AA was able to identify (though not name) faces normally. These profiles suggest that AA has conjoint (or interacting) deficits involving both apperceptive and semantic processing of accents, while PA has a primary semantic (associative) deficit affecting accents along with other kinds of auditory objects and extending beyond the auditory modality. Brain MRI revealed left peri-Sylvian atrophy in case AA and relatively focal asymmetric (predominantly right sided) temporal lobe atrophy in case PA. These cases provide further evidence for the fractionation of brain mechanisms for complex sound analysis, and for the stratification of progressive aphasia syndromes according to the signature of nonverbal auditory deficits they produce.

Multi-stage identification for abnormal/warning sounds detection based on maximum likelihood classification

In recent years, the methods utilizing environmental sounds have been increasingly employed for monitoring the safety of the elder who lives in distant place. Environmental sounds should consist of various sounds in daily life, and identified ones enables to detect abnormity. To detect abnormity, it is therefore required that abnormal/warning sounds are accurately identified among environmental sounds. In the past, environmental sound identification methods have generally utilized acoustic models constructed by each sound source for all environmental sounds. In our former research, we proposed multi-stage identification for detecting abnormal/warning sounds accurately. However, these methods design individual acoustic models from similar sounds. Therefore, the sound identification performance is degraded. To overcome this problem, in this study, we proposed environmental sound classification based on acoustic features for model construction. The proposed method classifies environmental sounds based on the difference of acoustic likelihood and designs acoustic models are constructed by classification results. Moreover, the proposed method detects the abnormal/warning sounds more accurately by combining it with the multi-stage identification. We carried out the evaluation experiment with environmental sound database. Experimental results of this experiment demonstrate that the identification performance for the proposed method is higher than that for the conventional methods.

Auditory and cognitive factors underlying individual differences in aided speech-understanding among older adults

This study was designed to address individual differences in aided speech understanding among a relatively large group of older adults. The group of older adults consisted of 98 adults (50 female and 48 male) ranging in age from 60 to 86 (mean = 69.2). Hearing loss was typical for this age group and about 90% had not worn hearing aids. All subjects completed a battery of tests, including cognitive (6 measures), psychophysical (17 measures), and speech-understanding (9 measures), as well as the Speech, Spatial, and Qualities of Hearing (SSQ) self-report scale. Most of the speech-understanding measures made use of competing speech and the non-speech psychophysical measures were designed to tap phenomena thought to be relevant for the perception of speech in competing speech (e.g., stream segregation, modulation-detection interference). All measures of speech understanding were administered with spectral shaping applied to the speech stimuli to fully restore audibility through at least 4000 Hz. The measures used were demonstrated to be reliable in older adults and, when compared to a reference group of 28 young normal-hearing adults, age-group differences were observed on many of the measures. Principal-components factor analysis was applied successfully to reduce the number of independent and dependent (speech understanding) measures for a multiple-regression analysis. Doing so yielded one global cognitive-processing factor and five non-speech psychoacoustic factors (hearing loss, dichotic signal detection, multi-burst masking, stream segregation, and modulation detection) as potential predictors. To this set of six potential predictor variables were added subject age, Environmental Sound Identification (ESI), and performance on the text-recognition-threshold (TRT) task (a visual analog of interrupted speech recognition). These variables were used to successfully predict one global aided speech-understanding factor, accounting for about 60% of the variance.

The Influence of Environmental Sound Training on the Perception of Spectrally Degraded Speech and Environmental Sounds

Perceptual training with spectrally degraded environmental sounds results in improved environmental sound identification, with benefits shown to extend to untrained speech perception as well. The present study extended those findings to examine longer-term training effects as well as effects of mere repeated exposure to sounds over time. Participants received two pretests (1 week apart) prior to a week-long environmental sound training regimen, which was followed by two posttest sessions, separated by another week without training. Spectrally degraded stimuli, processed with a four-channel vocoder, consisted of a 160-item environmental sound test, word and sentence tests, and a battery of basic auditory abilities and cognitive tests. Results indicated significant improvements in all speech and environmental sound scores between the initial pretest and the last posttest with performance increments following both exposure and training. For environmental sounds (the stimulus class that was trained), the magnitude of positive change that accompanied training was much greater than that due to exposure alone, with improvement for untrained sounds roughly comparable to the speech benefit from exposure. Additional tests of auditory and cognitive abilities showed that speech and environmental sound performance were differentially correlated with tests of spectral and temporal-fine-structure processing, whereas working memory and executive function were correlated with speech, but not environmental sound perception. These findings indicate generalizability of environmental sound training and provide a basis for implementing environmental sound training programs for cochlear implant (CI) patients.

Multi-stage identification for abnormal/warning sounds with onomatopoeia models

In recent years, the methods utilizing environmental sounds have been increasingly employed for monitoring the safety of the elder who lives in distant place. Environmental sounds should consist of various sounds in daily life, and identified ones enables to detect abnormity. To detect abnormity, it is therefore required that abnormal/warning sounds are accurately identified among environmental sounds. In the past, environmental sound identification method has utilized acoustic models constructed by each sound source for all environmental sounds. However, as it only stores a few training abnormal/warning sounds, it is difficult to accurately design each abnormal/warning acoustic model. To overcome this problem, we propose a multi-stage identification method for abnormal/warning sounds. In the first stage, it utilizes an abnormal/alarm acoustic sound model and each normal acoustic sound model for detecting the abnormal/alarm sounds with a few training abnormal/warning sounds. In the second stage, it utilizes some acoustic models specializing in onomatopoeia to accurately identify abnormal and alarm sounds. We conducted an evaluation experiment to confirm the effectiveness of the proposed method on identification accuracy of abnormal/warning sounds. As a result, we confirmed that the proposed method was superior to the conventional method in identification accuracy.

Perception of environmental sounds by experienced cochlear implant patients.

Environmental sound perception serves an important ecological function by providing listeners with information about objects and events in their immediate environment. Environmental sounds such as car horns, baby cries, or chirping birds can alert listeners to imminent dangers as well as contribute to one's sense of awareness and well being. Perception of environmental sounds as acoustically and semantically complex stimuli may also involve some factors common to the processing of speech. However, very limited research has investigated the abilities of cochlear implant (CI) patients to identify common environmental sounds, despite patients' general enthusiasm about them. This project (1) investigated the ability of patients with modern-day CIs to perceive environmental sounds, (2) explored associations among speech, environmental sounds, and basic auditory abilities, and (3) examined acoustic factors that might be involved in environmental sound perception. Seventeen experienced postlingually deafened CI patients participated in the study. Environmental sound perception was assessed with a large-item test composed of 40 sound sources, each represented by four different tokens. The relationship between speech and environmental sound perception and the role of working memory and some basic auditory abilities were examined based on patient performance on a battery of speech tests (HINT, CNC, and individual consonant and vowel tests), tests of basic auditory abilities (audiometric thresholds, gap detection, temporal pattern, and temporal order for tones tests), and a backward digit recall test. The results indicated substantially reduced ability to identify common environmental sounds in CI patients (45.3%). Except for vowels, all speech test scores significantly correlated with the environmental sound test scores: r = 0.73 for HINT in quiet, r = 0.69 for HINT in noise, r = 0.70 for CNC, r = 0.64 for consonants, and r = 0.48 for vowels. HINT and CNC scores in quiet moderately correlated with the temporal order for tones. However, the correlation between speech and environmental sounds changed little after partialling out the variance due to other variables. Present findings indicate that environmental sound identification is difficult for CI patients. They further suggest that speech and environmental sounds may overlap considerably in their perceptual processing. Certain spectrotemproral processing abilities are separately associated with speech and environmental sound performance. However, they do not appear to mediate the relationship between speech and environmental sounds in CI patients. Environmental sound rehabilitation may be beneficial to some patients. Environmental sound testing may have potential diagnostic applications, especially with difficult-to-test populations and might also be predictive of speech performance for prelingually deafened patients with cochlear implants.

The incongruency advantage for environmental sounds presented in natural auditory scenes.

The effect of context on the identification of common environmental sounds (e.g., dogs barking or cars honking) was tested by embedding them in familiar auditory background scenes (street ambience, restaurants). Initial results with subjects trained on both the scenes and the sounds to be identified showed a significant advantage of about five percentage points better accuracy for sounds that were contextually incongruous with the background scene (e.g., a rooster crowing in a hospital). Further studies with naive (untrained) listeners showed that this incongruency advantage (IA) is level-dependent: there is no advantage for incongruent sounds lower than a Sound/Scene ratio (So/Sc) of -7.5 dB, but there is about five percentage points better accuracy for sounds with greater So/Sc. Testing a new group of trained listeners on a larger corpus of sounds and scenes showed that the effect is robust and not confined to a specific stimulus set. Modeling using spectral-temporal measures showed that neither analyses based on acoustic features, nor semantic assessments of sound-scene congruency can account for this difference, indicating the IA is a complex effect, possibly arising from the sensitivity of the auditory system to new and unexpected events, under particular listening conditions.

可聴周波数と視覚的コンテクストが難聴者の環境音識別に与える影響について : 事例の分析をもとに

可聴周波数と視覚的コンテクストが難聴者の環境音識別に与える影響について : 事例の分析をもとに

Transfer of Auditory Perceptual Learning with Spectrally Reduced Speech to Speech and Nonspeech Tasks: Implications for Cochlear Implants

The objective of this study was to assess whether training on speech processed with an eight-channel noise vocoder to simulate the output of a cochlear implant would produce transfer of auditory perceptual learning to the recognition of nonspeech environmental sounds, the identification of speaker gender, and the discrimination of talkers by voice. Twenty-four normal-hearing subjects were trained to transcribe meaningful English sentences processed with a noise vocoder simulation of a cochlear implant. An additional 24 subjects served as an untrained control group and transcribed the same sentences in their unprocessed form. All subjects completed pre- and post-test sessions in which they transcribed vocoded sentences to provide an assessment of training efficacy. Transfer of perceptual learning was assessed using a series of closed set, nonlinguistic tasks: subjects identified talker gender, discriminated the identity of pairs of talkers, and identified ecologically significant environmental sounds from a closed set of alternatives. Although both groups of subjects showed significant pre- to post-test improvements, subjects who transcribed vocoded sentences during training performed significantly better at post-test than those in the control group. Both groups performed equally well on gender identification and talker discrimination. Subjects who received explicit training on the vocoded sentences, however, performed significantly better on environmental sound identification than the untrained subjects. Moreover, across both groups, pre-test speech performance and, to a higher degree, post-test speech performance, were significantly correlated with environmental sound identification. For both groups, environmental sounds that were characterized as having more salient temporal information were identified more often than environmental sounds that were characterized as having more salient spectral information. Listeners trained to identify noise-vocoded sentences showed evidence of transfer of perceptual learning to the identification of environmental sounds. In addition, the correlation between environmental sound identification and sentence transcription indicates that subjects who were better able to use the degraded acoustic information to identify the environmental sounds were also better able to transcribe the linguistic content of novel sentences. Both trained and untrained groups performed equally well ( approximately 75% correct) on the gender-identification task, indicating that training did not have an effect on the ability to identify the gender of talkers. Although better than chance, performance on the talker discrimination task was poor overall ( approximately 55%), suggesting that either explicit training is required to discriminate talkers' voices reliably or that additional information (perhaps spectral in nature) not present in the vocoded speech is required to excel in such tasks. Taken together, the results suggest that although transfer of auditory perceptual learning with spectrally degraded speech does occur, explicit task-specific training may be necessary for tasks that cannot rely on temporal information alone.

Informational factors in identifying environmental sounds in natural auditory scenes

In a non-linguistic analog of the "cocktail-party" scenario, informational and contextual factors were found to affect the recognition of everyday environmental sounds embedded in naturalistic auditory scenes. Short environmental sound targets were presented in a dichotic background scene composed of either a single stereo background scene or a composite background scene created by playing different background scenes to the different ears. The side of presentation, time of onset, and number of target sounds were varied across trials to increase the uncertainty for the participant. Half the sounds were contextually congruent with the background sound (i.e., consistent with the meaningful real-world sound environment represented in the auditory scene) and half were incongruent. The presence of a single competing background scene decreased identification accuracy, suggesting an informational masking effect. In tandem, there was a contextual pop-out effect, with contextually incongruent sounds identified more accurately. However, when targets were incongruent with the real-world context of the background scene, informational masking was reduced. Acoustic analyses suggested that this contextual pop-out effect was driven by a mixture of perceptual differences between the target and background, as well as by higher-level cognitive factors. These findings indicate that identification of environmental sounds in naturalistic backgrounds is an active process that requires integrating perceptual, attentional, and cognitive resources.

The effect of visual context on the identification of ambiguous environmental sounds

The influence of the specificity of the visual context on the identification of environmental sounds (i.e., product sounds) was investigated. Two different visual context types (i.e., scene and object contexts)—which varied in the specificity of the semantic information—and a control condition (meaningless images) were employed. A contextual priming paradigm was used. Identification accuracy and response times were determined in two context conditions and one control condition. The results suggest that visual context has a positive effect on sound identification. In addition, two types of product sounds (location-specific and event-specific sounds) were observed which exhibited different sensitivities to scene and object contexts. Furthermore, the results suggest that conceptual interactions exist between an object and a context that do not share the same perceptual domain. Therefore, context should be regarded as a network of conceptually associated items in memory.

Non-verbal auditory cognition in patients with temporal epilepsy before and after anterior temporal lobectomy

For patients with pharmaco-resistant temporal epilepsy, unilateral anterior temporal lobectomy (ATL) – i.e. the surgical resection of the hippocampus, the amygdala, the temporal pole and the most anterior part of the temporal gyri – is an efficient treatment. There is growing evidence that anterior regions of the temporal lobe are involved in the integration and short-term memorization of object-related sound properties. However, non-verbal auditory processing in patients with temporal lobe epilepsy (TLE) has raised little attention. To assess non-verbal auditory cognition in patients with temporal epilepsy both before and after unilateral ATL, we developed a set of non-verbal auditory tests, including environmental sounds. We could evaluate auditory semantic identification, acoustic and object-related short-term memory, and sound extraction from a sound mixture. The performances of 26 TLE patients before and/or after ATL were compared to those of 18 healthy subjects. Patients before and after ATL were found to present with similar deficits in pitch retention, and in identification and short-term memorisation of environmental sounds, whereas not being impaired in basic acoustic processing compared to healthy subjects. It is most likely that the deficits observed before and after ATL are related to epileptic neuropathological processes. Therefore, in patients with drug-resistant TLE, ATL seems to significantly improve seizure control without producing additional auditory deficits.

Vibrotactile identification of signal-processed sounds from environmental events

This study compared three different signal-processing principles (eight basic algorithms)-transposing, modulating, and filtering-to find the principle(s)/algorithm(s) that resulted in the best tactile identification of environmental sounds. The subjects were 19 volunteers (9 female/10 male) who were between 18 and 50 years old and profoundly hearing impaired. We processed sounds produced by 45 representative environmental events with the different algorithms and presented them to subjects as tactile stimuli using a wide-band stationary vibrator. We compared eight algorithms based on the three principles (one unprocessed, as reference). The subjects identified the stimuli by choosing among 10 alternatives drawn from the 45 events. We found that algorithm and subject were significant factors affecting the results (repeated measures analysis of variance, p < 0.001). We also found large differences between individuals regarding which algorithm was best. The test-retest variability was small (mean +/- 95% confidence interval = 8 +/- 3 percentage units), and no correlation was noted between identification score and individual vibratory thresholds. One transposing algorithm and two modulating algorithms led to significantly better results than did the unprocessed signals (p < 0.05). Thus, the two principles of transposing and modulating were appropriate, whereas filtering was unsuccessful. In future work, the two transposing algorithms and the modulating algorithm will be used in tests with a portable vibrator for people with dual sensory impairment (hearing and vision).

Development of a Large-Item Environmental Sound Test and the Effects of Short-Term Training with Spectrally-Degraded Stimuli

Accurate identification of environmental sounds plays an important role in maintaining listeners' awareness of their environment, and is a major concern for cochlear implant patients. Although research indicates that decreased spectral resolution has a negative effect on environmental sound identification, little is known about the processes underlying perceptual adaptation to spectrally-degraded input. The goals of this study were (1) to develop a test of environmental sound perception containing a large variety of easily identifiable and familiar sound sources, represented by multiple exemplars, and (2) to examine whether auditory training improves listeners' identification of spectrally-degraded environmental sounds. In experiment 1, familiarity ratings and identification accuracy were obtained for 21 normal-hearing subjects for 48 environmental sound sources; there were 4 exemplars of each sound source, for a total of 192 stimuli. A second test was developed using a subset of 40 sound sources (4 exemplars each, for a total of 160 stimuli). In experiment 2, seven normal-hearing subjects (who did not participate in experiment 1) were asked to identify spectrally-degraded environmental sounds processed by a four-channel noise-band vocoder. The second stimulus set developed in experiment 1 (40 sound sources, 4 exemplars each) was used in experiment 2. The subjects were tested in a pretest-posttest design with five training sessions between the pretest and the posttest. The training sounds were selected individually for each subject, and comprised one half of the sound sources that were misidentified in the pretest. Each sound source used in training was represented by two exemplars. During training, subjects received trial and block feedback. For each incorrect response, subjects were allowed to replay the stimulus up to five times after being shown the correct response. In experiment 1, listeners' average identification accuracy was 95% correct, with 178 of all sounds identified with an accuracy of 80% or more. The average identification accuracy of the 160 sounds selected for experiment 2 was 98% correct, and their average familiarity rating was 6.39 (on a 7-point scale). In experiment 2, the average identification accuracy of spectrally-degraded sounds was 33% correct on the pretest. However, after training, average identification accuracy across all sounds improved to 63% correct on the posttest. The largest improvement (86 percentage points) was obtained for the sound exemplars used during training. The identification accuracy for alternative exemplars of the training sounds (that referenced the same sources) improved by 36 percentage points. Finally, the identification of sound sources not included in the training, but perceived with equal difficulty on the pretest, improved by 18 percentage points. These results demonstrate positive effects of training on the identification of spectrally-degraded environmental sounds and suggest that training effects can generalize to other sound exemplars and sources, although with a reduced magnitude of improvement. The findings also indicate a timeline for initial perceptual adaptation to spectrally-degraded environmental sounds, and provide a preliminary basis for incorporating environmental sounds into auditory rehabilitation programs for cochlear implant patients.