Beginning at the age of about 14 months, eight children who lived in a rhotic dialect region of the United States were recorded approximately every 2 months interacting with their parents. All were recorded until at least the age of 26 months, and some until the age of 31 months. Acoustic analyses of speech samples indicated that these young children acquired [inverted r] production ability at different ages for [inverted r]'s in different syllable positions. The children, as a group, had started to produce postvocalic and syllabic [inverted r] in an adult-like manner by the end of the recording sessions, but were not yet showing evidence of having acquired prevocalic [inverted r]. Articulatory limitations of young children are posited as a cause for the difference in development of [inverted r] according to syllable position. Specifically, it is speculated that adult-like prevocalic [inverted r] production requires two lingual constrictions: one in the mouth, and the other in the pharynx, while postvocalic and syllabic [inverted r] requires only one oral constriction. Two lingual constrictions could be difficult for young children to produce.

Objective-To determine the maximum stimulus levels at which a measured auditory steady-state response (ASSR) can be assumed to be a reliable measure of auditory thresholds.Design-ASSR thresholds were measured at octave frequencies from 500 to 4000 Hz in 10 subjects with profound hearing loss. These subjects provided no behavioral responses to sound at the limits of pure-tone audiometers and at the limits of the stimulus levels produced by the ASSR device. Subjects were divided into two groups of five, with repeated measures obtained within the same session in one group and repeated measures obtained in a separate session on a different day in the other group.Results-ASSR thresholds were observed in all 10 subjects at each of four frequencies and in both trials. On average, these ASSR thresholds were observed at 100 dB HL (SD = 5 dB). Because these responses were at least 18 to 22 dB below the limits of the equipment where all subjects had no behavioral responses, it is reasonable to conclude that the ASSRs were not generated by the auditory system.Conclusions-An artifact or distortion may be present in the recording of ASSRs at high levels. These data bring into question the view that there is a wider dynamic range for ASSR measurements compared with auditory brain stem response measurements, at least with current implementation.With the advent of universal newborn hearing screening (UNHS), clinicians are being asked to provide diagnostic audiological evaluations on infants within the first few weeks or months of life. This seems reasonable, since it is widely thought that the success of intervention will depend, at least in part, on the age at which intervention begins (Moeller, 2000; YoshinagaItano et al., 1998). Thus, if UNHS identifies newborn infants with hearing loss, it will be important to initiate intervention as soon as possible after the identification. At these ages, however, it is not clinically feasible to rely on behavioral responses to sound to provide an estimate of the magnitude and configuration of hearing loss. Clinicians must rely on measurements that do not require a voluntary response on the part of the infant if intervention is to be initiated soon after identification.The auditory brainstem response (ABR) is considered an objective electrophysiological measure and has been used to provide information about auditory sensitivity in patients who are either too young or who are functioning at a developmental level at which reliable behavioral response measurements are not possible. These responses are elicited by stimuli with rapid onsets. Such stimuli are characterized by a spread of energy, the extent of which depends on how these stimuli are generated. Several stimulus paradigms have been combined with ABR measurements to obtain frequency-specific responses. These methods include the derived-band technique (Don, Eggermont and Brackman, 1979), the notched-noise technique (Picton et al., 1979;Stapells, Gravel and Martin, 1995), and the use of tone bursts in quiet (Gorga et al., 1988...

Previous studies found that children’s judgments of syllable-initial /s/ and /∫/ are more related to the vocalic F2 transition and less related to the fricative-noise spectrum than are adults’ judgments [e.g., Nittrouer, J. Phon. 20, 351–382 (1992)]. Such results have led to a model of speech development proposing that children’s weighting of acoustic cues changes as they gain linguistic experience. The present study tested two requisites of that model, namely that the perceptual weighting of acoustic cues must be flexible and cannot simply reflect a listener’s auditory sensitivities. Adults and 3-year olds participated in two tasks: Identification tasks, using synthetic fricative noises and either natural or synthetic vocalic portions; and discrimination tasks, measuring sensitivity to fricative-noise spectrum and F2 transition. Identification tasks showed the same age-related differences found in earlier studies when natural vocalic portions were used, but these age effects were reduced when synthetic vocalic portions were used. Discrimination tasks showed slightly larger difference thresholds for both the fricative noise and the F2 transition for children than for adults, but this age effect could not explain the age effect on the weighting of those cues for identification. It was concluded that the weighting of acoustic cues is flexible both for adults and for children, and that age-related differences in the weighting of the cues to /s/ and /∫/ are not explained by age-related differences in auditory sensitivities. [Work supported by NIH.]

The development of children’s /r/ production is the subject of a current investigation of a longitudinal database of children’s speech. Nine children were recorded interacting with a parent in approximately 2-month intervals from the age of about 15 months to the age of about 31 months. It would be expected that many of these children would not produce /r/ in an adult manner [e.g., M. M. Vihman and M. Greenlee, J. Speech Hear. Res. 30 (1987)], but the properties of children’s production of /r/ as a function syllable position and the production of r-colored vowels has not been examined closely. We have examined two children from this database for their ability to produce /r/ and r-colored vowels in various syllable positions. These children more readily produce postvocalic /r/ and r-colored vowels than they produce prevocalic /r/. Further, it may be that practice with intervocalic /r/ may help in future productions of prevocalic /r/’s. These observations will be quantified using formant frequency and amplitude measures and compared with the productions of /r/ by other children in the database.

Several acoustic properties can influence listeners’ judgments of voicing for syllable-final stops, including vocalic length. Developmental and cross-linguistic experiments have suggested that listeners with little experience about how vocalic length is related to final-stop voicing weight this property less than more-experienced listeners. For five (English, CVC) minimal pairs, we examined the acoustic consequences of final-stop voicing, as well as listeners’ weighting of two properties that signal voicing: vocalic length and syllable-offset transitions. First, an acoustic analysis of words showed that differences in vocalic length associated with final-stop voicing are attenuated when words occur in continuous speech, raising questions about how much experience any listener really has hearing vocalic-length differences correlated with final-stop voicing. Next, adults and children (3, 5, and 7 years old) labeled natural stimuli made from words that originally had voiced or voiceless stops, in which we modified vocalic length. Partial correlations revealed that listeners of all ages weighted offset transitions more than vocalic length. In fact, listeners were reluctant to label any stimulus that did not have transitions clearly indicating closure as ‘‘voiced,’’ and so the traditional ‘‘vocalic-length effect’’ was apparent only for originally voiced stimuli. We conclude that dynamic information takes precedence in this perceptual decision.