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Biomedical subjects

B A Schneider

Publications and source records attributed to B A Schneider.

At least 19 recordsLinked to original sources
PubMed1997

Noise-limited detection in young and old observers.

11 young (M age = 24.3 yr.) and 11 old (M age = 67.4 yr.) observers attempted to detect signals of limited bandwidth in visual noise. The older observers did not perform as well as the young ones. We considered whether, as suggested by a current hypothesis, these differences could be attributed to higher internal additive noise in the elderly observers. The results suggested that internal noise did not differ across the two age groups and that the lower performance of the older observers stemmed instead from reduced processing efficiency.

Adult↗
PubMed1997

Binaural additivity of loudness in children and adults.

Thirty-six different binaural noises were formed by crossing six right-ear intensities of a broadband noise with the same six intensities in the left ear in a 6 X 6 factorial design. Children (6-7 years of age) and adults were presented with 2 of these 36 binaural noises on a trial and asked to indicate which noise was louder. In Experiment 1, the left- and right-ear noises were in phase and differed only in intensity. In Experiment 2, the left- and right-ear noises were in opposite phase. For both the children and adults in Experiments 1 and 2, the paired comparison judgments of binaural loudness were shown to satisfy the testable axioms of conjoint measurement (transitivity and double cancellation), permitting the determination of interval scales of loudness for the left ear, right ear, and the sum of the two ears. Power functions provided a good description of the relation between loudness and sound pressure for the left and right ears of both children and adults. For both adults and children, an examination of the pattern of differences in judgments between Experiments 1 and 2 indicated that, when the noises were in phase, the contribution of the right ear to fused loudness was greater than when the noises were presented in counterphase.

Adult↗
PubMed1995

Age-related changes in binocular vision: detection of noise-masked targets in young and old observers.

This study investigated the effects of age on binocular unmasking. This term denotes the fact that a visual signal embedded in noise is detected appreciably better when the stimulus complex contains interocular cues (dichoptic condition) than when such cues are absent (binoptic condition). Detection thresholds for two Gabor signals differing in spatial frequency were determined in young and old adults with no identifiable ocular pathologies. The signals were embedded, in both conditions, in two-dimensional Gaussian noise. Binocular Masking Level Differences, defined as the difference between the binoptic thresholds and the dichoptic thresholds, did not change with age; however, the older adults showed higher binoptic thresholds with both signals and higher dichoptic thresholds with only the lower-spatial-frequency signal. For both groups, binoptic and dichoptic thresholds increased with spatial frequency. The implications of these results are discussed.

Adult↗
PubMed1995

How young and old adults listen to and remember speech in noise.

Two experiments using the materials of the Revised Speech Perception in Noise (SPIN-R) Test [Bilger et al., J. Speech Hear. Res. 27, 32-48 (1984)] were conducted to investigate age-related differences in the identification and the recall of sentence-final words heard in a babble background. In experiment 1, the level of the babble was varied to determine psychometric functions (percent correct word identification as a function of S/N ratio) for presbycusics, old adults with near-normal hearing, and young normal-hearing adults, when the sentence-final words were either predictable (high context) or unpredictable (low context). Differences between the psychometric functions for high- and low-context conditions were used to show that both groups of old listeners derived more benefit from supportive context than did young listeners. In experiment 2, a working memory task [Daneman and Carpenter, J. Verb. Learn. Verb. Behav. 19, 450-466 (1980)] was added to the SPIN task for young and old adults. Specifically, after listening to and identifying the sentence-final words for a block of n sentences, the subjects were asked to recall the last n words that they had identified. Old subjects recalled fewer of the items they had perceived than did young subjects in all S/N conditions, even though there was no difference in the recall ability of the two age groups when sentences were read. Furthermore, the number of items recalled by both age groups was reduced in adverse S/N conditions. The resutls were interpreted as supporting a processing model in which reallocable processing resources are used to support auditory processing when listening becomes difficult either because of noise, or because of age-related deterioration in the auditory system. Because of this reallocation, these resources are unavailable to more central cognitive processes such as the storage and retrieval functions of working memory, so that "upstream" processing of auditory information is adversely affected.

Adult↗
PubMed1995

Gap detection in infants, children, and adults.

Listeners who were 6.5 months, 12 months, 5 years, and 21 years of age were required to discriminate a pair of 500-Hz, Gaussian-enveloped tone pips from a short 500-Hz tone of the same duration and total energy. Groups of 6.5-month-old infants were tested on a single gap duration: 8, 12, 16, 20, 28, or 40 ms. Groups of 12-month-olds were also tested on a single gap duration: 8, 12, 16, or 20 ms. The 5-year-old children and adults were tested on gap durations of 8, 12, and 16 ms. The mean performance of 6.5-month-olds significantly exceeded chance levels on all gap durations except 8 ms, and that of 12-month-olds was above chance levels on all gap durations. For 5-year-old children and adults, mean performance also exceeded chance levels for all gap durations tested. Adults performed significantly better than 5-year-old children on gap durations of 12 and 16 ms. Gap-detection thresholds, defined by a performance criterion of d' = 0.5, were estimated at 11, 5.6, and 5.2 ms for infants, children, and adults, respectively. It is likely that smaller adult-infant differences in the present study compared to those reported in previous research stem from our use of Gaussian-enveloped tone pips and the consequent minimization of adaptation effects.

Adolescent↗
PubMed1994

Gap detection and the precedence effect in young and old adults.

Thresholds for detecting a gap between two Gaussian-enveloped (standard deviation = 0.5 ms), 2-kHz tones were determined in young and old listeners. The gap-detection thresholds of old adults were more variable and about twice as large as those obtained from young adults. Moreover, gap-detection thresholds were not correlated with audiometric thresholds in either group. Estimates of the width of the temporal window of young subjects, based on the detection of a gap between two tone pips, were smaller than those typically obtained when a relatively long duration pure tone is interrupted [Moore et al., J. Acoust. Soc. Am. 85, 1266-1275 (1989)]. Because the amount of time it takes to recover from an adapting stimulus is likely to affect gap detection thresholds [Glasberg et al., J. Acoust. Soc. Am. 81, 1546-1556 (1987)], smaller estimates of temporal window size would be expected in this paradigm if the amount of adaptation produced by the first tone pip was negligible. The larger gap-detection thresholds of old subjects indicate that they may have larger temporal windows than young subjects. The lack of correlation between audiometric and gap-detection thresholds indicates that this loss of temporal acuity is not related to the degree of sensorineural hearing loss. In a second experiment on the precedence effect using the same subjects, a Gaussian-enveloped tone was presented over earphones to the left ear followed by the same tone pip presented to the right ear. To more realistically approximate a sound field situation, the tone pip presented to each ear was followed 0.6 ms later by an attenuated version presented to the contralateral ear. The delay between the left- and right-ear tone-pips was varied and the transition point between hearing a single tone on the left, and hearing two such sounds in close succession (one coming from the left and the other from the right) was determined. The transition point in this experiment did not differ between young and old subjects nor were these transition points correlated with gap-detection thresholds. These results indicate that monaural temporal acuity and binaural echo suppression may be based on different processes.

Acoustic Stimulation↗
PubMed1992

The effect of interaural delay of the masker on masking-level differences in young and old adults.

Diotic (SoNo) thresholds and dichotic (S pi N pi tau) thresholds were measured for young and old adults using a 500-Hz pure-tone signal and broadband burst masking noise at 37 dB SPL/Hz. In the dichotic condition both the signal and the masker were phase reversed and the masker was presented with an interaural delay of 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 3, or 5 ms. Masking-level differences (MLDs) were determined by subtracting dichotic thresholds from diotic thresholds. The SoNo thresholds for the old subjects did not differ significantly from those for the young subjects; however, when MLDs were plotted as a function of delay, the pattern of results differed significantly between young and old subjects. This difference in pattern was completely accounted for in terms of a delay-line version of Durlach's equalization and cancellation (EC) model [N. I. Durlach, in Foundations of Modern Auditory Theory, edited by J. V. Tobias (Academic, New York, 1972); B. A. Schneider and P. M. Zurek, J. Acoust. Soc. Am. 86, 1756-1763 (1989)] by assuming that temporal jitter increases with internal delay in young subjects but that it does not vary with the amount of internal delay in old subjects.

Adult↗
PubMed1991

Masking-level differences in the elderly: a comparison of antiphasic and time-delay dichotic conditions.

Four dichotic thresholds (S pi N0, S0 N pi, S0 N tau, and S pi N pi tau) were measured for young and old subjects using both burst and continuous broadband maskers. Masking-level differences (MLDs) were determined by subtracting dichotic thresholds from homophasic thresholds (S0 N0 or S pi N pi). The S0 N0 thresholds for the old subjects did not differ significantly from those for the young subjects in either the continuous or the burst masking noise conditions. The S pi N pi thresholds for the old subjects did not differ significantly from those for the young subjects in the continuous masking noise condition, but there was a significant age effect (3 dB) when burst masking noise was used. Both young and old subjects obtained larger MLDs in continuous masking noise than in burst masking noise. MLDs for old subjects were smaller than MLDs for young subjects by 4.3, 5.0, 2.7, and 1.6 dB in burst masking noise and by 4.9, 3.5, 2.5, and 1.4 dB in continuous masking noise, respectively in the S pi N0, S pi N pi tau, S0 N tau, and S0 N pi conditions. Four young subjects there was a hierarchy in the size of the MLD obtained in the four dichotic conditions, with the MLD being significantly larger in the S pi N0 and S pi N pi tau conditions; however, the size of the MLD was the same in all four conditions for the old subjects. Compared to young subjects, the performance of the old subjects was characterized by decreased ability to use homophasic cues in burst masking noise and decreased ability to use interaural difference cues. These findings were observed at four signal frequencies.

Acoustics↗
PubMed1991

Developmental perspectives on the localization and detection of auditory signals.

Responsiveness of 1-, 3-, and 5-year-old children and adults to octave-band noises at .4 and 10 kHz was assessed with a go/no-go version of visual reinforcement audiometry (VRA) (Moore, Thompson, & Thompson, 1975) and a two-alternative, forced-choice version (Suzuki & Ogiba, 1961; Trehub, Schneider, & Endman, 1980). Infants performed better on the two-alternative, forced-choice version in quiet and in noisy backgrounds, and adults performed better on the two-alternative, forced-choice version in quiet but not in noisy backgrounds. Performance on the two tasks was essentially equivalent for 3- and 5-year-old children. Superior performance on two-alternative VRA over go/no-go may be due to lesser cognitive demands in the case of infants and to the engagement of superior decision strategies in the case of adults.

Adolescent↗
PubMed1990

Size of critical band in infants, children, and adults.

Masked thresholds at two signal frequencies (0.8 and 4 kHz) were obtained from listeners aged 6.5 months, 2 years, 5 years, and 20.5 years in the presence of constant spectrum level, narrowband maskers of differing bandwidths. Consistent with the classical results of Fletcher (1940), masked threshold for all age groups increased with bandwidth up to a critical width, beyond which further increases in bandwidth were ineffective in increasing threshold. These critical widths (estimates of critical band size) did not change substantially with age (critical widths for infants were no more than 50% larger than those of adults) despite substantial changes in masked thresholds with age. Thus, contrary to previous claims, changes in auditory filter width cannot account for developmental changes in masked or absolute thresholds.

Adolescent↗
PubMed1990

Intensity discrimination and loudness for tones in broadband noise.

In two previous papers (Parker & Schneider, 1980; Schneider & Parker, 1987), we developed a model, based on Fechner's assumption, which successfully predicted the relationship between loudness and intensity discrimination for tones presented in quiet and in notched noise. In the present paper, pure-tone intensity-increment thresholds and loudness matches were determined for several levels of a standard tone in the presence of a broadband masker whose spectrum level was set to 35 dB below that of the standard tone. The model was unable to relate loudness to intensity discrimination under these conditions. Thus, the spectral composition of the masker affects the relationship between loudness and intensity discrimination in ways that cannot be accounted for by the model.

Adult↗
PubMed1989

Developmental changes in masked thresholds.

Masked thresholds for octave-band noises with center frequencies of 0.4, 1, 2, 4, and 10 kHz and for a 1/3-octave-band noise centered at 10 kHz were obtained from listeners 6.5 months to 20.5 years of age at two levels of a broadband masker (0 and 10 dB/cycle). Thresholds declined exponentially as a function of age for all stimuli tested. The rate and extent of this decline, but not its asymptote, were independent of the frequency or bandwidth employed. The time course for this change parallels that found for electrophysiological maturation of more central auditory processes.

Adolescent↗
PubMed1989

Lateralization of coherent and incoherent targets added to a diotic background.

Lateralization responses to noise targets were obtained in a diotic noise background. On each trial, a noise target was added to the background noise in one earphone. Subjects were required to identify the earphone containing the target. Noise targets were either coherent or incoherent with the background. The long-term power spectrum of the incoherent target was identical to that of the background noise, and its amplitude was adjusted so that the addition of either the coherent or incoherent target to the background produced the same average increment in power. When 50-ms noise targets were presented in the middle of a 750-ms diotic background, lateralization thresholds were lower for the incoherent targets. The advantage with incoherent targets was shown to depend on the temporal relationships between target and masker. Superior performance with incoherent targets is inconsistent with predictions based on an analysis of interaural phase and amplitude differences. Models based on interaural subtraction, on the other hand, are able to account for the lateralization advantage shown by incoherent targets but are unable to account for the variations in threshold produced by altering the temporal relationships between target and masker.

Acoustic Stimulation↗
PubMed1989

Developmental changes in high-frequency sensitivity.

Sensitivity to 1/3-octave-band noises with centre frequencies of 10, 20, and 25 kHz was measured for 200 children between 1.5 and 16 years of age and for 20 young adults. In the case of the 25-kHz signal, listeners of 1.5 and 3 years of age as well as those 16 and 20 years of age were unable to detect it at its highest intensity (57 dB). In contrast, listeners 5-14 years of age could detect the 25-kHz signal. Sensitivity to the 20-kHz signal improved until about 8 years of age, deteriorating gradually thereafter. Finally, sensitivity to the 10-kHz signal improved rapidly, reaching young adult levels by 5 years of age, and remaining stable until 20 years of age. These findings are consistent with the onset of high-frequency hearing losses at around 10 years of age. Whether such hearing losses are due to normal aging (presbyacusis) or to noise exposure (socioacusis) remains to be determined.

Adolescent↗
PubMed1988

Auditory sensitivity in school-age children.

Thresholds for octave-band noises with center frequencies of 0.4, 1, 2, 4, and 10 kHz and 1/3-octave-band noises centered at 10 and 20 kHz were obtained from children 6 to 16 years of age. Such thresholds, combined with those obtained previously for infants, preschool children, and adults, provide a detailed picture of developing auditory sensitivity between infancy and maturity. Continuing improvements in sensitivity are evident from infancy through the preschool period, well into the school years. For stimuli with center frequencies of 0.4 and 1 kHz, maximal sensitivity is achieved at about 10 years of age, compared to 8 years for stimuli of 2 and 4 kHz. For 10-kHz stimuli, there is little change beyond 4 or 5 years of age. Finally, 20-kHz stimuli yield maximal sensitivity at about 6 or 8 years of age, followed by a progressive decline to adult levels. These findings are considered in relation to auditory sensitivity in nonhuman species, to structural and functional development of the ear, and to possible changes in the efficiency of neural processing.

Adolescent↗
PubMed1988

Binaural unmasking in infants.

Localization responses to a broadband noise signal presented against a broadband noise masker were obtained from 12-month-old infants and adults. Two loudspeakers, one to the left and one to the right of the listener, continuously presented identical broadband maskers. On a trial, a broadband signal was added to one of the loudspeakers. Subjects were required to identify the loudspeaker producing the signal. Noise signals were either coherent (from the same noise generator) or incoherent (from an independent noise generator). Both infants and adults found it easier to locate the incoherent signals even when the two types of signals were adjusted to produce equal increments in power. Since monaural performance, after this adjustment, should be equivalent for the two cases, superior performance for incoherent signals implies that binaural processing is involved. The same result was observed in control experiments in which coherent and incoherent signals were presented over earphones to adults. These results suggest that the mechanisms responsible for binaural unmasking are operative by 12 months of age.

Adult↗