Effects of speaker variability and noise on Mandarin fricative identification by native and non-native listeners.

Speaker variability and noise are two common sources of acoustic variability. The goal of this study was to examine whether these two sources of acoustic variability affected native and non-native perception of Mandarin fricatives to different degrees. Multispeaker Mandarin fricative stimuli were presented to 40 native and 52 non-native listeners in two presentation formats (blocked by speaker and mixed across speakers). The stimuli were also mixed with speech-shaped noise to create five levels of signal-to- noise ratios. The results showed that noise affected non-native identification disproportionately. By contrast, the effect of speaker variability was comparable between the native and non-native listeners. Confusion patterns were interpreted with reference to the results of acoustic analysis, suggesting native and non-native listeners used distinct acoustic cues for fricative identification. It was concluded that not all sources of acoustic variability are treated equally by native and non-native listeners. Whereas noise compromised non-native fricative perception disproportionately, speaker variability did not pose a special challenge to the non-native listeners.

Identification of acoustically modified Mandarin tones by non-native listeners.

This study investigated identification of fragmented Mandarin tones by non-native listeners. Monosyllabic Mandarin words were digitally processed to generate intact, silent-center, center-only, and onset-only syllables. The syllables were recorded with two carrier phrases such that the offset of the carrier tone and the onset of the target tone were either continuous or discontinuous in fundamental frequency (F0). The syllables were presented with an original carrier phrase, excised from the carrier phrase, or excised and cross-spliced with another carrier phrase. Response accuracy and reaction time were measured, and tone confusion patterns were analyzed. Overall, tone identification varied as a function of modification and tone. Intact and center-only syllables were identified more accurately than silent-center and onset-only syllables. Tone 2 was consistently the most challenging tone to identify. Although the performance level of the third-year students approached that of native listeners reported in Lee, Tao, and Bond (2008), the non-native listeners did not show evidence of using coarticulatory information. Nonetheless, the continuity or discontinuity in F0 between the carrier and target tones did affect tone identification, suggesting the influence of context in non-native tone identification.

Morphological errors in casual conversation.

Occasionally, listeners' strategies for dealing with casual speech lead them into an erroneous perception of the intended message-a slip of the ear. When such errors occur, listeners report hearing, as clearly and distinctly as any correctly perceived stretch of speech, something that does not correspond to the speakers' utterance. From a collection of almost 1000 examples of misperceptions in English conversation, perceptual errors involving morphology suggest that listeners expect monomorphemic forms and treat phonological information as primary. Listeners are not particularly attentive to morphological information and may supply inflectional morphemes as needed by context.

Effect of whole-body vibration on acoustic measures of speech.

If Automatic Speech Recognition technology is to be applied in the cockpit, it must deal with speech produced under environmental conditions that may alter the acoustic characteristics of the speech to be recognized. The present study examines the acoustic-phonetic detail of selected words produced under vibration, with the talker wearing an oxygen mask. The duration of words and syllables showed small effects that were inconsistent and statistically non-significant. Statistically significant increases were found in fundamental frequency and in the proportion of energy in the higher frequencies (decreased spectral tilt). The vibration conditions examined had no consistent effect on the center frequencies of the vowel formants measured.

Effect of visual cuing on synthetic speech intelligibility: a comparison of native and nonnative speakers of English.

This study compared the effect of visual cuing on the intelligibility of DECtalk for native and nonnative speakers of English in both ideal listening conditions and in the presence of background noise at a signal to noise (S/N) ratio of + 10dB. Visual cuing improved DECtalk's intelligibility for nonnative speakers more than for native speakers, especially in the background noise condition. Implications of these findings and the need for further research are discussed.

Perceptual judgment of voice pitch during pitch-matching tasks.

This study investigated the perceptual judgment of voice pitch. 24 individuals were assigned to two groups to assess whether there is a difference in perceptual judgment of voice pitch during pitch-matching tasks. Group I, Naïve listeners, had no previous experience in anatomy, physiology, or voice pitch-evaluation methods. Group II, Experienced listeners, were master's level speech-language pathologists having completed academic training in evaluation of voice. Both groups listened to identical stimuli, which required matching audiotaped voice-pitch samples of a male and female voice to a note on an electronic keyboard. The experiment included two tasks. The first task assessed pitch range, which required matching of the lowest and highest voice pitch of both a male and female speaker singing /a/ to a note on a keyboard. The second task assessed habitual pitch, which required matching of the voice pitch of a word spoken by a male and female speaker to a note on a keyboard. A one-way analysis of variance indicated a significant difference between groups occurred for only one of four conditions measured, perceptual judgment of the female pitch range. No differences between groups were found in the perceptual judgments of the male pitch range or during perceptual judgment of the female or male habitual pitch, suggesting that the skill possessed by speech-language pathology students is no different from that of inexperienced listeners.

Possible influence of linguistic musical background on perceptual pitch-matching tasks: a pilot study.

Linguistic background has been identified as important in the perception of pitch, particularly between tonal versus nontonal languages. In addition, a link between native language and the perception of musical pitch has also been established. This pilot study examined the perception of pitch between listeners from tonal and nontonal linguistic cultures where two different styles of music originate. Listeners were 10 individuals born in China who ranged in age from 25 to 37 years and had spent on the average 30 mo. in the USA and 10 individuals, born on the Indian subcontinent, who ranged in age from 22 to 31 years, and had spent an average of 13 mo. in the USA. Listeners from both groups participated in two conditions. One condition involved listening to a selection of music characteristic of the individual's culture (China, pentatonic scale; Indian subcontinent, microtones), and one condition involved no music. All listeners within each condition participated in two voice pitch-matching tasks. One task involved matching the lowest and highest pitch of tape-recorded voices to a note on an electronic keyboard. Another task involved matching the voice pitch of tape-recorded orally read words to a note on the keyboard. There were no differences between the two linguistic groups. Methodological limitations preclude generalization but provide the basis for further research.

Interaction between auditory and oral sensory feedback in speech regulation.

To investigate the interaction between the auditory and oral sensory feedback modalities during speech production lingual vibrotactile thresholds were obtained from subjects in the following conditions: (1) before and after speech production with normal auditory feedback, (2) before and after speech production under exposure to auditory masking, and (3) before and after exposure to auditory masking without performing speech tasks. In addition duration measurements were obtained for selected speech sounds to investigate temporal changes in the articulatory patterns of subjects in the various conditions. Lingual sensory decreases and temporal reorganization were observed only in subjects speaking under auditory masking. These data suggest a balanced interaction between auditory and oral sensory feedback modalities which, when disturbed, results in non-phonemic change in speech production.

Interaction of sensory feedback: a child-adult comparison of oral sensory and temporal articulatory function.

Recent studies have demonstrated a systematic increase in lingual sensory thresholds and a temporal articulatory reorganization in subjects speaking under exposure to auditory masking. These data suggest that auditory and lingual sensory feedback systems exist in a balanced interaction specific to the oral articulations involved in speech production. The present study attempted to gain additional information on this proposed interaction. Lingual sensory and temporal articulatory measurements were obtained from 10 adults and 10 children under each of four feedback conditions: (1) normal feedback, (2) exposure to binaural auditory masking during speech, (3) topical application of anesthesia to the lingual dorsum prior to speech, and (4) combined masking and anesthesia. Analysis indicated that children had lower lingual sensory thresholds than adults in all conditions and that they were more susceptible to the disruption of auditory feedback. Also, measurements of durations of vowels indicated no age-related differences with durations in both groups increasing when auditory feedback was impaired.

Subjective phrase structure: An empirical investigation.

The present study represents an attempt to investigate the basis of subjective groupings of words in sentences, employing Edwin Martin's subjective phrase structure technique. Results indicate that subjects base their judgments not only on grammatical structure but also on constituent length and on stress and intonation patterns.

Identification of novel phonetic segments by children, adolescents and adults.

The ability of children, adolescents and adults to employ completely novel phonetic information was examined. Three groups of subjects were tested for their ability to identify minimal pairs contrasting voiced and implosive stops in syllable-initial position. Children's performance on this task was significantly superior to both adolescent and adult performance.

Acquisition of the voicing contrast language-delayed and normal-speaking children.

Voicing is a phonological contrast which emerges early in the speech of children. However, the acoustic correlates of the voicing contrast for stop consonants are fairly complex. In the initial position, voicing is cued primarily by the relative timing of articulatory versus laryngeal gestures. In the final position, the duration of the preceding vowel is associated with the voicing contrast of stop consonants. The purpose of this study was to examine the pattern of acquisition of the voicing contrast in the speech of ten children diagnosed as language-delayed in comparison with the acquisition of the voicing contrast by normal speaking children. The language-delayed and normal-speaking children were matched according to mean length of utterance (MLU) and placed in one of Brown's five developmental stages. Each participant was first given a short test, using natural speech, to determine his or her ability to identify minimal pairs differing in the voicing of stop consonants. Those who passed the test were recorded under standard recording conditions repeating 12 test words. The test words contrasted voiced and voiceless stop consonants in initial and final positions. Spectrograms of the three best productions of each word were used to examine voice-onset time for stops in initial position and preceding vowel duration for stops in final position. Although the language-delayed and normal-speaking children showed equivalent linguistic sophistication (as measured by MLU), the language-delayed children's control of the acoustic-phonetic details of the voicing contrast was less mature than that of the normal-speaking children.

/s/ plus stop clusters in children's speech.

Young children frequently substitute stops for fricative-stop clusters. In this paper, we report acoustic measurements for children's intended voiced and voiceless stops, and for stops substituting for clusters. Judging from voice-onset time measurements, children employ various strategies for assigning phonological status to the substituted stops.

Children's spontaneous and imitative speech: an acoustic-phonetic analysis.

The purpose of this study was to compare the voice onset time of voiced and voiceless stop consonants in children's spontaneous and imitative speech. Ten children (2:3 to 3:8) were recorded producing the same test words spontaneously and imitatively, following a model. There were no statistically significant differences between imitative and spontaneous productions.

Acoustic-phonetic characteristics of speech produced in noise and while wearing an oxygen mask.

The present study investigated changes in the prosodic and acoustic-phonetic features of isolated words by four male talkers speaking in quite and in pink noise at a level of 95 dB SPL. Speech samples were collected both with and without an oxygen mask. Changes in duration, fundamental frequency, total energy, and formant center frequency were analyzed. In addition to the expected changes of increased pitch and amplitude associated with speaking in noise without an oxygen mask, significant effects were found (particularly in the formant center frequencies) as a result of using the oxygen mask. When the oxygen mask was employed, no further significant changes were caused by adding noise to the speaking situation.