A preliminary account of phonological and morphophonological perception in young children with and without otitis media.

This investigation examined the effects of otitis media with effusion (OME) and its associated fluctuating conductive hearing loss on the perception of phonological and morphophonological /s/ and /z/ in young children. We predicted that children free of OME (OME-) would perform better than children with histories of OME (OME+). We also predicted that for the OME+ group morphological perception would be harder than phonological perception, because the former category carries an additional linguistic load (i.e., plurality). Sixteen children, ages 26 to 28 months (M = 26.5, SD = 0.6) were divided into two groups, the OME- (n = 8) and OME+ (n = 8) based on OME history during the first year of life. Subjects in the OME- group were free of the disease for 4/5 visits and pure tone average (PTA) was 12.6 dB HL (SD = 4.8). Subjects in the OME+ group had the disease on 3/5 visits and PTA was 23 dB HL (SD = 2.7). Experimental stimuli were six monosyllabic novel word-pairs. Members of each word-pair differed only in the presence of final voiced or voiceless fricative, marking the targets phonologically (e.g., [g [symbol: see text]]/[g [symbol: see text] s] as in 'law', 'loss') or morphophonologically (e.g., [daep]/[daeps] as in 'map' 'maps'). Subjects were taught the unfamiliar word pairs using a fast mapping procedure. Perception was tested with the bimodal preferential looking paradigm. Children in the OME- group performed significantly better than their OME+ counterparts. Individual word-pair analyses showed that OME+ group performed more poorly than the OME- group on one phonological and on two morphological targets, all ending with [s]. For the OME+ group, targets with final [s] posed greater difficulty than those with final [z], especially on morphophonological plural-(s) targets. The results suggested that the fluctuating hearing loss associated with OME might have a negative impact on speech perception.

Identification and discrimination of a synthesized voicing contrast by normal and sensorineural hearing-impaired children.

The identification and discrimination of a stop-consonant voicing contrast (/da/--/ta/) was assessed in children and adolescents who had moderate, severe, and profound sensorineural hearing losses. The location of the perceptual boundary between /da/ and /ta/ did not differ between normal listeners and listeners with moderate losses. Of the ten listeners with severe losses, five evidenced normal boundaries, three evidenced longer-than-normal boundaries, and two could not identify the stimuli at all. Of the three listeners with profound hearing losses, one could identify normally, and two could not identify at all. For the most part, discrimination data mirrored identification data. However, in some instances listeners were able to discriminate between stimuli they could not differentially identify. These subjects appeared to have the auditory capacity to resolve differences in voice-onset-time but could not use this capacity to make phonetic identification.

Distribution of acoustic cues for stop consonant place of articulation in VCV syllables.

Most theoretical accounts of the identification of stop consonant place of articulation have focused on how bursts and formant transitions conspire to signal place in CV syllables. In the present series of experiments we have examined the identification of place in VCV syllables and have found that not only do the burst and opening transitions affect the judgement of place, but so also do the closing transitions and the duration of the closure interval. This outcome is consistent with the outcomes of many other experiments in showing that there are multiple acoustic events which bear on the identification of a given phone and that those acoustic events are distributed over time. Theoretical accounts of place identification based on data of this kind may prove viable than theories based on data from the identification of place in the absolute, syllable-initial position.

Some experiments on the sound of silence in phonetic perception.

The results of several experiments demonstrate that silence is an important cue for the perception of stop-consonant and affricate manner. In some circumstances, silence is necessary; in others, it is sufficient. But silence is not the only cue to these manners. There are other cues that are more or less equivalent in their perceptual effects, though they are quite different acoustically. Finally, silence is effective as a cue when it separates utterances produced by male and female speakers. These findings are taken to imply that, in these instances, perception is constrained as if by some abstract conception of what vocal tracts do when they make linguistically significant gestures.

Some relationships between speech production and perception.

EMG studies of the American English vowel pairs /i-I/ and /e-epsilon/ reveal two different production strategies: some speakers appear to differentiate the members of each pair primarily on the basis to tongue height; for others the basis of differentiation appears to be tongue tension. There was no obvious reflection of these differences in the speech wave-forms or formant patterns of the two groups. To determine if these differences in production might correspond to differences in perception, two vowel identification tests were given to the EMG subjects. Subjects were asked to label the members of a seven-step vowel continuum, /i/ through /I/. In one condition each item had an equal probability of occurrence. The other condition was an anchoring test; the first stimulus, /i/, was heard four times as often as any other stimulus. Compared with the equal-probability test labelling boundary, the boundary in the anchoring test was displaced toward the more frequently occurring stimulus. The magnitude of the shift of the labelling boundary was greater for subjects using a production strategy based on tongue height than for subjects using tongue tension to differentiate these vowels, suggesting that the stimuli represent adjacent categories in the speakers' phonetic space for the former, but not for the latter, group.

Vowel and nasal duration as cues to voicing in word-final stop consonants: spectrographic and perceptual studies.

To determine durational differences between vowel and nasal segments preceding word-final /t/ and /d/, spectrograms were made of adult speakers' productions of minimal pairs of the type /pent/-/pend/. Vowel, nasal, and vowel plus nasal (vocalic nucleus) durations were greater before /d/ than before /t/. Assuming the voiceless context as a base, the increase in nasal duration in the voiced case was proportionately greater than the increase in vowel duration. This outcome suggests that nasal duration is a more powerful cue to the voicing characteristic of the following consonant than is vowel duration. To test this, adult listeners were presented synthetic CVNC utterances in which the nasal and vowel segments were independently varied in duration over a range of 40 msec to 200 msec and were instructed to label the final stop consonant as either voiced /d/ or voiceless /t/. Although changes in both vowel and nasal duration were sufficient to cue both voiced and voiceless judgements, listeners' categorization of final consonants shifted more rapidly as a result of varying nasal rather than vowel duration. Nasal duration, therefore, appears to be a stronger cue than vowel duration for the word-final voiced-voiceless consonant distinction in CVNC utterances.

Perception of temporal order in vowel sequences with and without formant transitions.

Temporal-order perception of phoneme segments in running speech is much superior to temporal-order perception in repeating vowel sequences. The more rapid rates possible in running speech may be due largely to the presence of formant transitions. In a series of five experiments we observed that many temporal-order misjudgements of repeating vowels can be explained in terms of auditory stream segregation, triggered for the most part by discontinuities in first-formant frequencies of adjacent vowels. Streaming, however, can be suppressed by formant transitions appropriate for the perception of stop consonants and by continuous transitions resembling those in coarticulated vowels. At rapid sequence rates, when the constraints of auditory streaming are removed, correct temporal-order identification is limited by linguistic transformations of vowels into other phoneme segments.

Tongue musculature and the feature of tension in English vowels.

Electromyographic techniques were employed to discover which, if any, intrinsic and extrinsic tongue muscles displayed a difference in overall amount of activity corresponding to the traditional tense-lax distinction between members of the English vowel pairs /i-I/, /e-epsilon/, and /u-u/. Although some muscles revealed a consistent difference, most did not. Even for those muscles where a tense-lax difference was found, the data do not support the notion that tension was a necessary of sufficient differentia of production.