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Thursday, May 15, 2008
Champagne Terrace/Bordeaux (Novotel London West)
10:30 AM
Background: Although the diagnosis of autism spectrum disorder (ASD) is largely based on abnormal social communication, and restricted/repetitive activities, abnormal sensory sensitivity is also prevalent. Anecdotal and experimental evidence suggest that individuals with ASD experience difficulty in understanding speech in noisy environments, such as classrooms.
Objectives: To investigate if this finding is the consequence of impaired masking release (defined as the difference between speech identification scores obtained in steady-state and temporally fluctuating noise), due to a less-than-normal ability to take advantage of the temporal dips in the background in order to take “glimpses” of the target speech signal.
Methods: Six normal-hearing children with Asperger’s syndrome (AS) and six age- and IQ-matched typically-developing control children were tested (age range = 11-15 years). Participants and their parents completed a questionnaire as a subjective measure of everyday listening difficulties. Identification scores were obtained for nonsense vowel-consonant-vowel (VCV) stimuli, containing 21 English consonants in an /a/ vowel context, presented in silence and a speech-shaped background noise that was either steady and sinusoidally amplitude modulated (SAM) at modulation frequencies from 4 to 128 Hz.
Results: Speech identification in steady noise was initially lower for participants with AS, but this difference disappeared with further practice. Relative improvement in SAM noise in terms of overall percent correct and reception of phonetic features (i.e., voicing, manner, and place of articulation) showed a similar dependence on modulation frequency in both groups, but could be lower by up to 17% points in the AS group. However, these differences generally failed to reach statistical significance. Again, performance improved with practice over several test sessions.
Conclusions: Participants with AS did not show abnormal levels of masking release for VCV stimuli if training was provided. This observation contrasts with the questionnaire data showing auditory aversiveness and impaired speech-in-noise perception in the AS group.
Objectives: To investigate if this finding is the consequence of impaired masking release (defined as the difference between speech identification scores obtained in steady-state and temporally fluctuating noise), due to a less-than-normal ability to take advantage of the temporal dips in the background in order to take “glimpses” of the target speech signal.
Methods: Six normal-hearing children with Asperger’s syndrome (AS) and six age- and IQ-matched typically-developing control children were tested (age range = 11-15 years). Participants and their parents completed a questionnaire as a subjective measure of everyday listening difficulties. Identification scores were obtained for nonsense vowel-consonant-vowel (VCV) stimuli, containing 21 English consonants in an /a/ vowel context, presented in silence and a speech-shaped background noise that was either steady and sinusoidally amplitude modulated (SAM) at modulation frequencies from 4 to 128 Hz.
Results: Speech identification in steady noise was initially lower for participants with AS, but this difference disappeared with further practice. Relative improvement in SAM noise in terms of overall percent correct and reception of phonetic features (i.e., voicing, manner, and place of articulation) showed a similar dependence on modulation frequency in both groups, but could be lower by up to 17% points in the AS group. However, these differences generally failed to reach statistical significance. Again, performance improved with practice over several test sessions.
Conclusions: Participants with AS did not show abnormal levels of masking release for VCV stimuli if training was provided. This observation contrasts with the questionnaire data showing auditory aversiveness and impaired speech-in-noise perception in the AS group.