Barbara A. Morrongiello

Perceptual equivalence of acoustic cues in speech and nonspeech perception

Trading relations show that diverse acoustic consequences of minimal contrasts in speech are equivalent in perception of phonetic categories. This perceptual equivalence received stronger support from a recent finding that discrimination was differentially affected by the phonetic cooperation or conflict between two cues for the /slIt/-/splIt/contrast. Experiment 1 extended the trading relations and perceptual equivalence findings to the /sei/-/stei/contrast. With a more sensitive discrimination test, Experiment 2 found that cue equivalence is a characteristic of perceptual sensitivity to phonetic information. Using “sine-wave analogues” of the /sei/-/stei/stimuli, Experiment 3 showed that perceptual integration of the cues was phonetic, not psychoacoustic, in origin. Only subjects who perceived the sine-wave stimuli as “say” and “stay” showed a trading relation and perceptual equivalence; subjects who perceived them as nonspeech failed to integrate the two dimensions perceptually. Moreover, the pattern of differences between obtained and predicted discrimination was quite similar across the first two experiments and the “say”-“stay” group of Experiment 3, and suggested that phonetic perception was responsible even for better-than-predicted performance by these groups. Trading relations between speech cues, and the perceptual equivalence that underlies them, thus appear to derive specifically from perception of phonetic information.

Development of the perception of musical relations: Semitone and diatonic structure.

In the present research we examined the development of sensitivity to two musical relations significant in Western tonal music, the semitone and diatonic structure. Infants and preschool children were tested for their detection of a semitone change in any position of a five-note melody. Two standard melodies were used, one composed of diatonic tones only and the other containing a non-diatonic tone. In Experiment 1, children from 4 to 6 years of age were superior in detecting the semitone change in the diatonic context compared with the nondiatonic context. In Experiment 2, infants 9 to 11 months of age detected the semitone change in all positions, but their performance was not influenced by diatonic context. These findings indicate that infants and children can discriminate a semitone in a musical context and that the priority of diatonic structure emerges by 4 to 6 years of age.

Age-related changes in auditory temporal perception

The discrimination of signal and silence duration was evaluated in 6-month-old infants, 5 1/2-year-old children, and adults. Listeners were tested with a conditioned-discrimination procedure in which they were presented a sequence of 18 white-noise bursts and trained to discriminate a change in duration of the middle 6 signal or silence elements. There were no differential effects on performance for changes in signal compared to silence duration. At each age, performance varied only as a function of magnitude of duration change. Infants discriminated duration changes of 20 ms or greater, children discriminated 15 ms, and adults discriminated changes as small as 10 ms. These findings are consistent with other research in revealing age-related improvements in auditory temporal perception.

Infants' perception of melodies: Changes in a single tone*

Infants 6 to 8 months of age were exposed to repetitions of a 6-tone sequence or melody, then tested for their detection of six transformations of that sequence, each of which incorporated a frequency change in one of the six positions. In Experiment 1, infants showed evidence of discriminating all changes. Moreover, they performed significantly better on changes that extended the frequency range of the original melody. When the task was made more difficult in Experiment 2, performance deteriorated but frequency changes in all positions were still detectable.

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.

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.

Motivational Interviewing to Enhance Self-Efficacy and Promote Weight Loss in Overweight and Obese Adolescents: A Randomized Controlled Trial

OBJECTIVE To evaluate the efficacy of Motivational Interviewing (MI) as an intervention for promoting self-efficacy and weight loss in a sample of overweight and obese youth. METHODS /Design 40 participants (aged 10-18 years) were randomly assigned to control (social skills training) or treatment (MI) group. Both groups received individual therapy (~30 min/month) in addition to usual care of diet/exercise counseling. Pre- and post- (at 6 months follow-up) variables included measures of self-efficacy and anthropometrics. RESULTS Although significant between-group differences were not found, individuals in the MI group attended more sessions. Overall, participants in both groups showed significant increases in self-efficacy and a trend of decreased body mass index z-scores. CONCLUSIONS Health benefits from participation in individual therapy may have been accrued; however, specific benefits attributable to MI were limited. Findings suggest that more than one type of counseling intervention (i.e., MI and social skills training) may be beneficial when providing integrative treatment for obese youth.

Children's perception of melodies: The role of contour, frequency, and rate of presentation ☆

Children 4 to 6 years of age were exposed to repetitions of a six-tone melody, then tested for their detection of transformations that either preserved or changed the contour of the standard melody. Discrimination performance was examined as a function of contour condition, magnitude of contour change, rate of presentation, and the presence of novel frequencies. Performance was superior for transformations that changed contour compared to those that did not, for greater changes in contour, and for faster presentation rates. Melodies transformed by a reordering of component tones were no less discriminable than those transformed by the addition of novel frequencies.

Developmental Changes in Children's Perception of Musical Sequences: Effects of Musical Training.

Five- and 9-years-olds were presented a 9-note melody and asked to select the line drawing that best depicted the melodic contour, or the sequential pattern of rising and falling pitches. Melodies varied in tonality and contour complexity. Tonal melodies contained only diatonic notes, whereas atonal melodies also included some nondiatonic notes.

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.