Noise increment detection in children 1 to 3 years of age

Developmental Changes in the Perception of Vocal Loudness and Voice Quality in 3- to 6-Year-Old Children

PURPOSE

The study's primary aim was to investigate developmental changes in the perception of vocal loudness and voice quality in children 3-6 years of age. A second aim was to evaluate a testing procedure-the intermodal preferential looking paradigm (IPLP)-for the study of voice perception in young children.

METHOD

Participants were categorized in two age groups: 3- to 4-year-olds and 5- to 6-year-olds. Children were tested remotely via a Zoom appointment and completed two perceptual tasks: (a) voice discrimination and (b) voice identification. Each task consisted of two tests: a vocal loudness test and a voice quality test.

RESULTS

Children in the 5- to 6-year-old group were significantly more accurate than children in the 3- to 4-year-old group in discriminating and identifying differences between voices for both loudness and voice quality. The IPLP, used in the identification task, was found to successfully detect differences between the age groups for overall accuracy and for most of the sublevels of vocal loudness and voice quality.

CONCLUSIONS

Results suggest that children's ability to discriminate and identify differences in vocal loudness and voice quality improves with age. Findings also support the use of the IPLP as a useful tool to study voice perception in young children.

Effect of Realistic Test Conditions on Spectral and Temporal Processing in Normal-Hearing Listeners

Purpose To measure the effect of testing conditions (in the soundproof booth vs. quiet room), test order, and number of test sessions on spectral and temporal processing in normal-hearing (NH) listeners. Method Thirty-two adult NH listeners participated in the three experiments. For all three experiments, the stimuli were presented to the left ear at the subjects' most comfortable level through headphones. All tests were administered in an adaptive three-alternative forced-choice paradigm. Experiment 1 was designed to compare the effect of soundproof booth and quiet room test conditions on amplitude modulation detection threshold and modulation frequency discrimination threshold with each of the five modulation frequencies. Experiment 2 was designed to compare the effect of two test orders on the frequency discrimination thresholds under the quiet room test conditions. The thresholds were first measured in the ascending and descending order of four pure tones, and then with counterbalanced order. For Experiment 3, the amplitude discrimination threshold under the quiet room testing condition was assessed 3 times to determine the effect of the number of test sessions. Then the thresholds were compared over the sessions. Results Results showed no significant effect of test environment. The test order is an important variable for frequency discrimination, particularly between piano tunes and pure tones. Results also show no significant difference across test sessions. Conclusions These results suggest that a controlled test environment may not be required in spectral and temporal assessment for NH listeners. Under the quiet test environment, a single outcome measure is sufficient, but test orders should be counterbalanced.

Attention modifies sound level detection in young children

Have you ever shouted your child's name from the kitchen while they were watching television in the living room to no avail, so you shout their name again, only louder? Yet, still no response. The current study provides evidence that young children process loudness changes differently than pitch changes when they are engaged in another task such as watching a video. Intensity level changes were physiologically detected only when they were behaviorally relevant, but frequency level changes were physiologically detected without task relevance in younger children. This suggests that changes in pitch rather than changes in volume may be more effective in evoking a response when sounds are unexpected. Further, even though behavioral ability may appear to be similar in younger and older children, attention-based physiologic responses differ from automatic physiologic processes in children. Results indicate that 1) the automatic auditory processes leading to more efficient higher-level skills continue to become refined through childhood; and 2) there are different time courses for the maturation of physiological processes encoding the distinct acoustic attributes of sound pitch and sound intensity. The relevance of these findings to sound perception in real-world environments is discussed.

Factors affecting the processing of intensity in school-aged children

PURPOSE

Thresholds of school-aged children are elevated relative to those of adults for intensity discrimination and amplitude modulation (AM) detection. It is unclear how these findings are related or what role stimulus gating and dynamic envelope cues play in these results. Two experiments assessed the development of sensitivity to intensity increments in different stimulus contexts.

METHOD

Thresholds for detecting an increment in level were estimated for normal-hearing children (5- to 10-year-olds) and adults. Experiment 1 compared intensity discrimination for gated and continuous presentation of a 1-kHz tone, with a 65-dB-SPL standard level. Experiment 2 compared increment detection and 16-Hz AM detection introduced into a continuous 1-kHz tone, with either 35- or 75-dB-SPL standard levels.

RESULTS

Children had higher thresholds than adults overall. All listeners were more sensitive to increments in the continuous than the gated stimulus and performed better at the 75- than at the 35-dB-SPL standard level. Both effects were comparable for children and adults. There was some evidence that children's AM detection was more adultlike than increment detection.

CONCLUSION

These results imply that memory for loudness across gated intervals is not responsible for children's poor performance but that multiple dynamic envelope cues may benefit children more than adults.

Attention effects on auditory scene analysis in children

Auditory scene analysis begins in infancy, making it possible for the baby to distinguish its mother's voice from other noises in the environment. Despite the importance of this process for human behavior, the question of how perceptual sound organization develops during childhood is not well understood. The current study investigated the role of attention for perceiving sound streams in a group of school-aged children and young adults. We behaviorally determined the frequency separation at which a set of sounds was detected as one integrated or two separated streams and compared these measures with passively and actively obtained electrophysiological indices (mismatch negativity (MMN) and P3b) of the same sounds. In adults, there was a high degree of concordance between passive and active electrophysiological indices of stream segregation that matched with perception. In contrast, there was a large disparity in children. Active electrophysiological indices of streaming were concordant with behavioral measures of perception, whereas passive indices were not. In addition, children required larger frequency separations to perceive two streams compared to adults. Our results suggest that differences in stream segregation between children and adults reflect an under-development of basic auditory processing mechanisms, and indicate a developmental role of attention for shaping physiological responses that optimize processes engaged during passive audition.

Psychometric functions for pure tone intensity discrimination: slope differences in school-aged children and adults

Previous work on pure tone intensity discrimination in school-aged children concluded that children might have higher levels of internal noise than adults for this task [J. Acoust. Soc. Am. 120, 2777-2788 (2006)]. If true, this would imply that psychometric function slopes are shallower for children than adults, a prediction that was tested in the present experiment. Normal hearing children (5-9 yr) and adults were tested in a two-stage protocol. The first stage used a tracking procedure to estimate 71% correct for intensity discrimination with a gated 500 Hz pure tone and a 65 dB sound pressure level standard level. The mean and standard deviation of these tracks were used to identify a set of five signal levels for each observer. In the second stage of the experiment percent correct was estimated at these five levels. Psychometric functions fitted to these data were significantly shallower for children than adults, as predicted by the internal noise hypothesis. Data from both stages of testing are consistent with a model wherein performance is based on a stable psychometric function, with sensitivity limited by psychometric function slope. Across observers the relationship between slope and threshold conformed closely to predictions of a simple signal detection model.

The development of the perceptual organization of sound by frequency separation in 5-11-year-old children

The analysis of the auditory scene begins from the moment we hear sounds, making it possible for the infant to distinguish the mother's voice from other sounds in the environment. The purpose of the study was to determine, in two experiments, whether the frequency separation threshold, at which the perception of a mixture of sounds turns from being perceived as one stream to two streams, differs between two groups of school-aged children (ages 5-8 and 9-11 years) and adults. The results show a developmental course for the perception of auditory streams that is not simply dependent upon frequency discrimination. This suggests that maturation of the stream segregation process follows a longer developmental course than maturation of simple feature discrimination. The data indicate that the ability to hear distinct sound streams in the environment takes time to develop and becomes sharpened with experience and maturity.

The influence of spectral distinctiveness on acoustic cue weighting in children's and adults' speech perception

Children and adults appear to weight some acoustic cues differently in perceiving certain speech contrasts. One possible explanation for this difference is that children and adults make use of different strategies in the way that they process speech. An alternative explanation is that adult-child cue weighting differences are due to more general sensory (auditory) processing differences between the two groups. It has been proposed that children may be less able to deal with incomplete or insufficient acoustic information than are adults, and thus may require cues that are longer, louder, or more spectrally distinct to identify or discriminate between auditory stimuli. The current study tested this hypothesis by examining adults' and 3- to 7-year-old children's cue weighting for contrasts in which vowel-onset formant transitions varied from spectrally distinct (/no/-/mo/, /do/-/bo/, and /ta/-/da/) to spectrally similar (/ni/-/mi/, /de/-/be/, and /ti/-/di/). Spectrally distinct cues were more likely to yield different consonantal responses than were spectrally similar cues, for all listeners. Furthermore, as predicted by a sensory hypothesis, children were less likely to give different consonantal responses to stimuli distinguished by spectrally similar transitional cues than were adults. However, this pattern of behavior did not hold for all contrasts. Implications for theories of adult-child cue weighting differences are discussed.

Vowel perception by adults and children with normal language and specific language impairment: based on steady states or transitions?

The current investigation studied whether adults, children with normally developing language aged 4-5 years, and children with specific language impairment, aged 5-6 years identified vowels on the basis of steady-state or transitional formant frequencies. Four types of synthetic tokens, created with a female voice, served as stimuli: (1) steady-state centers for the vowels [i] and [ae]; (2) voweless tokens with transitions appropriate for [bib] and [baeb]; (3) "congruent" tokens that combined the first two types of stimuli into [bib] and [baeb]; and (4) "conflicting" tokens that combined the transitions from [bib] with the vowel from [baeb] and vice versa. Results showed that children with language impairment identified the [i] vowel more poorly than other subjects for both the voweless and congruent tokens. Overall, children identified vowels most accurately in steady-state centers and congruent stimuli (ranging between 94%-96%). They identified the vowels on the basis of transitions only from "voweless" tokens with 89% and 83.5% accuracy for the normally developing and language impaired groups, respectively. Children with normally developing language used steady-state cues to identify vowels in 87% of the conflicting stimuli, whereas children with language impairment did so for 79% of the stimuli. Adults were equally accurate for voweless, steady-state, and congruent tokens (ranging between 99% to 100% accuracy) and used both steady-state and transition cues for vowel identification. Results suggest that most listeners prefer the steady state for vowel identification but are capable of using the onglide/offglide transitions for vowel identification. Results were discussed with regard to Nittrouer's developmental weighting shift hypothesis and Strange and Jenkin's dynamic specification theory.