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Objective: The ability to discriminate natural soundscapes recorded in a temperate terrestrial biome was measured in 15 hearing-impaired (HI) listeners with bilateral, mild to severe sensorineural hearing loss and 15 normal-hearing (NH) controls. Design: Soundscape discrimination was measured using a three-interval oddity paradigm and the method of constant stimuli. On each trial, sequences of 2-second recordings varying the habitat, season and period of the day were presented diotically at a nominal SPL of 60 or 80 dB. Results: Discrimination scores were above chance level for both groups, but they were poorer for HI than NH listeners. On average, the scores of HI listeners were relatively well accounted for by those of NH listeners tested with stimuli spectrally-shaped to match the frequency-dependent reduction in audibility of individual HI listeners. However, the scores of HI listeners were not significantly correlated with pure-tone audiometric thresholds and age. Conclusions: These results indicate that the ability to discriminate natural soundscapes associated with changes in habitat, season and period of the day is disrupted but it is not abolished. The deficits of the HI listeners are partly accounted for by reduced audibility. Supra-threshold auditory deficits and individual listening strategies may also explain differences between NH and HI listeners. [ABSTRACT FROM AUTHOR]

Purpose: Children with dyslexia have been suggested to experience deficits in both categorical perception (CP) and speech identification in noise (SIN) perception. However, results regarding both abilities are inconsistent, and the relationship between them is still unclear. Therefore, this study aimed to investigate the relationship between CP and the psychometric function of SIN perception. Method: Sixteen children with dyslexia, 16 chronological-age controls, and 16 reading-level controls were evaluated in CP of a voicing continuum and in consonant identification in both stationary and fluctuating noises. Results: There was a small but significant impairment in speech identification performance of children with dyslexia in stationary noise compared with chronological age--matched controls (but not reading level--matched controls). However, their performance increased in a fluctuating background, hence suggesting normal masking and unmasking effects and preserved sensory processing of speech information. Regarding CP, location of the phoneme boundary differed in the children with dyslexia compared with both control groups. However, scrutinizing individual profiles failed to reveal consistently poor performance in SIN and CP tasks. In addition, there was no significant correlation between CP, SIN perception, and reading scores in the group with dyslexia. Conclusions: The relationship between the SIN deficit and CP, and how they potentially affect reading in children with dyslexia, remains unclear. However, these results are inconsistent with the notion that children with dyslexia suffer from a low-level temporal processing deficit and rather suggest a role of nonsensory (e.g., attentional) factors in their speech perception difficulties.

Purpose: This study assessed the role of spectro-temporal modulation cues in the discrimination of 2 phonetic contrasts (voicing and place) for young infants. Method: A visual-habituation procedure was used to assess the ability of French-learning 6-month-old infants with normal hearing to discriminate voiced versus unvoiced (/aba/-/apa/) and labial versus dental (/aba/-/ada/) stop consonants. The stimuli were processed by tone-excited vocoders to degrade frequency-modulation cues while preserving: (a) amplitude-modulation (AM) cues within 32 analysis frequency bands, (b) slow AM cues only (<16 Hz) within 32 bands, and (c) AM cues within 8 bands. Results: Infants exhibited discrimination responses for both phonetic contrasts in each processing condition. However, when fast AM cues were degraded, infants required a longer exposure to vocoded stimuli to reach the habituation criterion. Conclusions: Altogether, these results indicate that the processing of modulation cues conveying phonetic information on voicing and place is "functional" at 6 months. The data also suggest that the perceptual weight of fast AM speech cues may change during development.

Research in hearing sciences has provided extensive knowledge about how the human auditory system processes speech and assists communication. In contrast, little is known about how this system processes "natural soundscapes," that is the complex arrangements of biological and geophysical sounds shaped by sound propagation through non-anthropogenic habitats [Grinfeder et al. (2022). Frontiers in Ecology and Evolution. 10: 894232]. This is surprising given that, for many species, the capacity to process natural soundscapes determines survival and reproduction through the ability to represent and monitor the immediate environment. Here we propose a framework to encourage research programmes in the field of "human auditory ecology," focusing on the study of human auditory perception of ecological processes at work in natural habitats. Based on large acoustic databases with high ecological validity, these programmes should investigate the extent to which this presumably ancestral monitoring function of the human auditory system is adapted to specific information conveyed by natural soundscapes, whether it operate throughout the life span or whether it emerges through individual learning or cultural transmission. Beyond fundamental knowledge of human hearing, these programmes should yield a better understanding of how normal-hearing and hearing-impaired listeners monitor rural and city green and blue spaces and benefit from them, and whether rehabilitation devices (hearing aids and cochlear implants) restore natural soundscape perception and emotional responses back to normal. Importantly, they should also reveal whether and how humans hear the rapid changes in the environment brought about by human activity. [ABSTRACT FROM AUTHOR]

Purpose: The capacity of 6-month-old infants to discriminate a voicing contrast (/aba/--/apa/) on the basis of "amplitude modulation (AM) cues" and "frequency modulation (FM) cues" was evaluated. Method: Several vocoded speech conditions were designed to either degrade FM cues in 4 or 32 bands or degrade AM in 32 bands. Infants were familiarized to the vocoded stimuli for a period of either 1 or 2 min. Vocoded speech discrimination was assessed using the head-turn preference procedure. Results: Infants discriminated /aba/ from /apa/ in each condition; however, familiarization time was found to influence strongly infants' responses (i.e., their preference for novel vs. familiar stimuli). Conclusions: Six-month-old infants do not require FM cues and can use the slowest (< 16 Hz) AM cues to discriminate voicing. Moreover, 6-month-old infants can use AM cues extracted from only 4 broad-frequency bands to discriminate voicing.

Purpose: To investigate the capacity of young children and adults with normal hearing to discriminate speech on the basis of either relatively slow (temporal envelope, E) or fast (temporal fine structure, TFS) auditory cues. Method: Vowel-consonant-vowel nonsense disyllables were processed to preserve either the E or the TFS information in 16 adjacent frequency bands. The band signals were then recombined and resulting stimuli were presented for discrimination to adults or 5-, 6-, and 7-year-old children using an odd-ball paradigm. Discrimination scores (d') and response latencies were measured in each listener. No training was given to listeners. Results: Overall, discrimination scores were high (d' greater than or equal to 1) in all speech-processing conditions, and did not differ across age groups. Overall, and irrespective of age, greater discrimination scores and shorter response latencies were observed for E speech than for TFS speech. Conclusions: These results suggest that normal-hearing children are able to encode and use E and TFS speech cues at adult levels by the age of 5 years. TFS- and E-coded speech stimuli might therefore prove to be a useful tool for the investigation of the developmental time course of speech perception, and for the early diagnosis of peripheral and central auditory processing disorders.

This study evaluated the ability to process auditory temporal-envelope cues in six children with dyslexia and two groups of six each normal control children and adults. Children with dyslexia showed poorer reception of voicing, manner, and place of articulation for unprocessed speech and poorer reception of voicing for "speech-envelope noise." (Contains references.) (Author/LC)