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Biomedical subjects

J M Lindholm

Publications and source records attributed to J M Lindholm.

8 recordsLinked to original sources
PubMed1988

Stimulus factors influencing the identification of voiced stop consonants by normal-hearing and hearing-impaired adults.

The effects of mild-to-moderate hearing impairment on the perceptual importance of three acoustic correlates of stop consonant place of articulation were examined. Normal-hearing and hearing-impaired adults identified a stimulus set comprising all possible combinations of the levels of three factors: formant transition type (three levels), spectral tilt type (three levels), and abruptness of frequency change (two levels). The levels of these factors correspond to those appropriate for /b/, /d/, and /g/ in the /ae/ environment. Normal-hearing subjects responded primarily in accord with the place of articulation specified by the formant transitions. Hearing-impaired subjects showed less-than-normal reliance on formant transitions and greater-than-normal reliance on spectral tilt and abruptness of frequency change. These results suggest that hearing impairment affects the perceptual importance of cues to stop consonant identity, increasing the importance of information provided by both temporal characteristics and gross spectral shape and decreasing the importance of information provided by the formant transitions.

Adult↗
PubMed1987

Vowel intelligibility in the absence of the acoustic reflex: performance-intensity characteristics.

Performance-intensity functions were defined for ten synthetic vowels whose durations (50 ms) were shorter than the time necessary for the acoustic reflex to alter the transmission characteristics of the middle ear. Recognition accuracy for ten listeners with normal auditory function was asymptotic from 72 to 90 dB and then fell linearly to 108 dB. Thus, at SPLs greater than approximately 90 dB, the auditory encoding of vowels is altered by the absence of the acoustic reflex.

Adult↗
PubMed1986

Influence of the acoustic reflex on vowel recognition.

Computer synthesized vowels of 50- and 300-ms duration were presented to normal-hearing listeners at a moderate and high sound pressure level (SPL). Presentation at the high SPL resulted in poor recognition accuracy for vowels of a duration (50 ms) shorter than the latency of the acoustic stapedial reflex. Presentation level had no effect on recognition accuracy for vowels of sufficient duration (300 ms) to elicit the reflex. The poor recognition accuracy for the brief, high intensity vowels was significantly improved when the reflex was preactivated. These results demonstrate the importance of the acoustic reflex in extending the dynamic range of the auditory system for speech recognition.

Air Pressure↗
PubMed1985

Influence of the first formant on the recognition of voiced stop consonants by hearing-impaired listeners.

In order to examine first formant masking effects in hearing-impaired listeners, bay, day, and gay were synthesized with and without a first formant. The signals were presented at several levels. Removal of the first formant did not improve intelligibility at levels above, at, or below the point of maximum intelligibility. These results and others converge to suggest that masking spread from the first formant is not a significant factor in the identification of voiced stop consonants by listeners with sloping, mild-to-moderate hearing loss.

Aged↗
PubMed1985

Phonetic identification by elderly normal and hearing-impaired listeners.

Young normal-hearing listeners, elderly normal-hearing listeners, and elderly hearing-impaired listeners were tested on a variety of phonetic identification tasks. Where identity was cued by stimulus duration, the elderly hearing-impaired listeners evidenced normal identification functions. On a task in which there were multiple cues to vowel identity, performance was also normal. On a/b d g/identification task in which the starting frequency of the second formant was varied, performance was abnormal for both the elderly hearing-impaired listeners and the elderly normal-hearing listeners. We conclude that errors in phonetic identification among elderly hearing-impaired listeners with mild to moderate, sloping hearing impairment do not stem from abnormalities in processing stimulus duration. The results with the /b d g/continuum suggest that one factor underlying errors may be an inability to base identification on dynamic spectral information when relatively static information, which is normally characteristic of a phonetic segment, is unavailable.

Adult↗
PubMed1980

Aging, dichotic memory and digit span.

Comparisons were made between groups of old and young subjects in a dichotic task. In the first experiment old and young subjects had digit spans representative of their respective populations, and in accord with previous dichotic research younger subjects recalled with greater accuracy. The main effect of group and the Group x Test (ear reported first vs ear reported second) interaction were reliable with both serial and free recall scoring. In the second experiment young subjects were matched to old subjects on the basis of digit span. Matching eliminated the group and Group x Test interaction with seriall recall and the group effect with free recall, suggesting that digit span and dichotic memory are mediated by common mechanisms. Error trends and the Group x Test interactions with free recall revealed that some age related differences persisted even after matching. These differences are discussed in terms of regression artifact and processing capacity.

Adolescent↗