bluuebunny/crossref_metadata_2025 huggingface dataset:
Some acoustic evidence of systematic patterns of pre-aspiration in Norwegian
Authors: Moxness Bente Henrikka
Published: October 2005

The study investigates the subphonemic feature of pre-aspiration in Norwegian. Pre-aspiration occurs between a vowel and a following voiceless stop consonant. Ten subjects were recorded (five females, five males), producing six repetitions of 36 Norwegian nonsense words (18 monosyllables and 18 disyllables). The acoustic analysis of the speech material was carried out using the Signalyze 3.12 software program. Previously, it has been proposed that pre-aspiration occurs in languages that have no voice/voiceless opposition in the phonetic sense [H. Thrainsson, Nord. J. Linguist. 1, 3–54 (1978)]. However, Norwegian does have a phonetic distinction between voiced and voiceless stops. The study will show that pre-aspiration is present in Norwegian VC[-voice]-rhymes. Norwegian also displays a phonemic opposition between V:C- and VC:-rhymes, an opposition manifested phonetically in segment durations [Behne and Moxness, J. Acoust. Soc. Am.95 , 2979(A) (1994)]. The present study will show that duration of pre-aspiration is greater in VC:-rhymes as opposed to V:C-rhymes, and that pre-aspiration is greater in disyllables as opposed to monosyllables. The conclusion drawn is that pre-aspiration may serve as a redundant feature to length, signaling voicelessness of the stop consonant in Norwegian VC[voice]-rhymes.
An acoustic study of Italian unstressed mid-vowels
Authors: Baroni Marco
Published: October 2005

In Italian, the contrast between the two mid front vowels |eε| and between the two mid back vowels |o■| is neutralized in unstressed syllables, where the two pairs merge into the unstressed mid ‘‘archiphonemes’’ |EO|. In this study, an instrumental investigation of the quality of the unstressed mid-vowels is presented to see if neutralization is complete (phonetically), and to determine the nature of |EO| in different contexts. The preliminary results show that there is no statistical difference between an |E| alternating with |e|, an |E| alternating with |ε|, and an |E| that does not alternate with any stressed vowel. The same holds for the mid-back vowel series. In addition, pre-tonic |EO| are realized as mid-high vowels (their average F1 values indicate that they are slightly higher than stressed |eo|), while post-tonic |EO| are realized as mid-low vowels (their average F1 values indicate that they are very similar to stressed |ε■|). In neither case is a significant centralization effect observed. Finer grain distinctions between pre and post-tonic |EO| in different contexts will be examined further.
The role of variable vowel duration in differentiating stop phonation in Korean
Authors: Cho Taehong
Published: October 2005

While vowel duration is known to be significantly influenced by the voicing of the following consonants, little has been found regarding environmental effects of the preceding consonants on vowel duration. This study investigates the environmental effect of both the preceding and the following consonants on vowel duration and shows that, in Korean, vowel length is affected by: (1) voicing of the following consonant and (2) phonation type (e.g., plain, aspirated, reinforced) of the preceding consonant. In the quantitative study of the durational relationship among temporal units (e.g., stop closure, VOT) and adjacent vowels, it is found that the vowel duration is correlated with the phonation type of the preceding consonant: A vowel is longer after reinforced stops, intermediate after plain stops, and shortest after aspirated stops. Unlike the anticipatory consonantal voicing effects, these progressive effects function as a cue for the three-way phonation distinction of Korean stops. The overall results indicate that to fully account for the three-way phonation distinction in Korean, it is necessary to expand the traditional approach (i.e., examining only the target consonant itself) by investigating the acoustic behavior of vocalic elements in the target’s immediate environment.
Variation in degree of nasalization for Mandarin vowels with superimposed rhoticity
Authors: Zhang Jie
Published: October 2005

It is documented that, in Mandarin Chinese, the realization of the diminutive suffix /r/ on a syllable with vowel-nasal finals is shaped by place of articulation of the nasal. For both [n] and [■] finals, the nasal is deleted and rhotacization is superimposed on the vowel. However, for [■] final, the vowel is also nasalized. Four native speakers of Beijing Mandarin (two male, two female) were recorded for this experiment. Nasal and oral airflow of rhotacized vowels with both nasal endings was measured, and the results agreed with the earlier documentation. Nasal and oral airflow of nonrhotacized vowels with both nasal endings will also be measured. To account for the difference in nasalization for rhotacized vowels, the following hypothesis will be tested: The anticipatory effect on the vowel preceding [■] is greater than that on the vowel preceding [n]. Therefore, the vowel preceding [■] is expected to be more nasalized than the vowel preceding [n] in nonrhotacized context although the degree of nasalization is small. This leads to the distinction in nasalization for vowels in rhotacized context. Other possible articulatory and acoustic accounts of the variation will also be discussed.
An analysis of fluctuation on sustained vowel waveforms from the viewpoint of 1/f shimmers
Authors: Aoki Naofumi , Ifukube Tohru
Published: October 2005

The naturalness factor of sustained vowels has been mainly attributed to a fundamental frequency fluctuation called jitter. However, sustained human vowels, with a fundamental frequency that is made to be constant, still sound natural [Ifukube et al., J. Acoust. Soc. Jpn. 47, 903–910 (1991)]. In order to investigate this fact, 128 pitch periods of the sustained vowel /a/ were analyzed. The maximum peak amplitude of each pitch period, which was placed at relatively the same position through 128 pitch periods, was extracted to make a time series that is called shimmer. Using FFT analysis, the shimmer turned out to have a 1/f fluctuation characteristic. This time series characteristic is often found in the biomedical signal processing area. This finding is thought to be classified as one of these signals. Not only does the maximum peak shimmer show 1/f fluctuation characteristics, but other peak shimmers show the same characteristics. In order to investigate the role of 1/f shimmer, a psychoacoustic experiment was conducted. Acoustic stimuli that sound like the vowel /a/ were made by means of a PARCOR synthesizer with various kinds of shimmer. The results showed that the stimulus with 1/f shimmer was recognized to be more humanlike.
Matching verbal organizations heard with voiced and whispered vowel sequences
Authors: Chalikia Magdalene H. , Laurila Jessica
Published: October 2005

Research shows that listeners exposed to a repeated sequence of steady-state vowels experience phonemic transformations, and hear words and phrases absent in the original stimulus. Similar observations have been made with whispered stimuli. This study investigated the similarity in the organizations heard with voiced and whispered vowel sequences, each made up of six vowels. Listeners heard each set of stimuli and reported what they heard with each arrangement. Then, additional stimuli were presented identical to the first two sets but with the duration of each vowel longer by 40 ms. These stimuli were presented in a different order, and listeners were asked to match each sequence to the verbal organizations heard initially. Most listeners were able to perform the task when the stimulus conditions corresponded to the organization conditions: ‘‘all voiced’’ or ‘‘all whispered.’’ Listeners also performed the matching task in the ‘‘voiced/whispered’’ condition (when they were asked to match voiced stimuli to organizations heard with whispered stimuli) and in the ‘‘whispered/voiced’’ condition (when whispered stimuli were matched to organizations heard with voiced stimuli). The results suggest similarities between perceptual mechanisms responsible for these effects and mechanisms involved in the processing of speech.
Logistic regression analysis of the perception of natural and synthesized /hVd/ syllables
Authors: Nearey Terrance M. , Kiefte Michael , Hillenbrand James M.
Published: October 2005

Hillenbrand and Nearey (abstract 3aSC12) present results of a perceptual experiment involving the identification of 300 natural and 600 synthetic /hVd/ syllables of American English. Results of linear logistic regression of the same data are presented which confirm and clarify the basic findings of the companion paper. This analysis allows the optimized fitting of a generalized linear model to listeners’ responses using stimulus properties as predictors [T. M. Nearey, J. Phon. 18, 347–373 (1990)]. Models including both nucleus and offglide formant measures (from steady-state and 80% of the total duration portions of the vocoids, respectively) reduce prediction error measures by about 50% over models including steady state measures only for dynamic formant stimuli. Evaluation of the contribution of individual formant and formant difference measures to specific vowel contrasts will be discussed. Comparisons will be made with results from linear discriminant analysis reported by Hillenbrand and Nearey.
Vowel formant discrimination in ordinary listening conditions. I
Authors: Kewley-Port Diane , Zheng Yijian
Published: October 2005

Compared to thresholds obtained with psychophysical procedures [Kewley-Port, J. Acoust. Soc. Am. 97, 3139–3146 (1995)], formant-frequency discrimination tasks using less well-trained listeners and relatively higher stimulus uncertainty yield severely degraded performance. The present study is the first step to examine formant discrimination under more natural listening conditions simulated by increasing the trial-to-trial stimulus uncertainty, the phonetic context of the target vowels, and the level of cognitive load. Difference limens (DLs) were obtained for F1 and F2 from four vowels in either CVC syllables, a three-word phrase or a nine-word sentence under medium stimulus uncertainty. Cognitive load was presumably increased in the sentence task with the addition of an identification response. Analyses of effects of the phonetic context demonstrated that DLs were significantly degraded between CVCs, phrases, and sentences in the F2 region, but in the F1 region were relative similar. For the sentence task, the effect of training was shown to improve discrimination significantly by about a factor of 2. However, after training, little difference was observed between the two tasks, discrimination only and discrimination and identification combined. These results suggest that effects of more central levels of auditory processing on discrimination need to be further investigated. [Supported by NIH-NIDCD-02229.]
The gestural organization of vowels: A cinefluorographic study of articulator gestures in Greenlandic
Authors: Wood Sidney A. J.
Published: October 2005

Movements of individual articulators are analyzed to elucidate principles of gestural organization in vowels. Procedures for tracking articulator gestures from x-ray motion films, and results obtained on coarticulation in Swedish, Bulgarian, and Greenlandic are reported in Wood [J. Phon. 19, 281–292 (1991); Proc. 3rd Congr. I. C. P. L. A. 191–200, Helsinki (1994); Proc. 13th I. C. Ph. Sc. 1, 392–395, Stockholm (1995); J. Phon. 24, 139–164 (1996); Proc. 4th Speech Prod. Seminar 61–64, Grenoble (1996)]. Tongue body movement was organized as predicted from a spectrographic study of Greenlandic vowels in Wood [Working Papers 4, 58–94, Lund (1971)] and according to the principles reported for English and Arabic in Wood [J. Phon. 7, 25–43 (1979)]. Greenlandic has three vowel phonemes, but the allophonic variation means all four tongue body gestures (palatal, velar, uvular, pharyngeal) are utilized. All articulator gestures needed for a vowel converged on a typical configuration, those arriving earlier being held until all were in position. The configuration was held briefly before the articulators were withdrawn. Coarticulation was organized by queuing oncoming gestures that are antagonistic to current gestures, avoiding conflicts.
The contribution of consonants versus vowels to word recognition in fluent speech
Authors: Cole Ron , Yan Yonghong , Mak Brian , Fanty Mark
Published: October 2005

Three perceptual experiments were conducted to test the relative importance of vowels versus consonants to recognition of fluent speech. Sentences were selected from the TIMIT corpus to obtain approximately equal numbers of vowels and consonants within each sentence and equal durations across the set of sentences. In experiments 1 and 2, subjects listened to (a) unaltered TIMIT sentences, (b) sentences in which all of the vowels were replaced by noise, or (c) sentences in which all of the consonants were replaced by noise. The subjects listened to each sentence five times, and attempted to transcribe what they heard. The results of these experiments show that recognition of words depends more upon vowels than consonants—about twice as many words are recognized when vowels are retained in the speech. The effect was observed when occurrences of [l], [r], [w], [y] [m], and [n] were included in the sentences (experiment 1) or replaced by noise (experiment 2). Experiment 3 tested the hypothesis that vowel boundaries contain more information about the neighboring consonants than vice versa.
Temporal effects on successive consonants in Swedish
Authors: Czigler Peter E. , Behne Dawn M.
Published: October 2005

The duration of phonetic components in a syllable is known to be affected by the syllable’s relative prominence, along with the number and articulatory nature of phonological segments in a word. This study addresses the durational effect of these factors on successive segments in Swedish consonant clusters. Ten native Swedish speakers were recorded producing monosyllabic and disyllabic target words which were either focused or not focused in a carrier phrase. Each word contained an /s/+stop cluster or stop+/s/ cluster in which the stop was /p,t/ or /k/. The durations of the /s/ frication and stop closure were measured. Results indicate that focus consistently increases the duration of a cluster and its constituents. In addition, little difference in closure duration was observed among /p,t,k/. Within disyllabic words, the cluster’s first segment, whether a stop or an /s/, was systematically longer than the second segment in both nonfocal and focal conditions. The reverse tendency was found for monosyllabic words; the cluster’s second segment was generally longer than the first segment in the focal condition, and no difference due to position in the cluster was observed for the nonfocal condition. These results are discussed in terms of the relative timing of successive consonants within clusters.
Voicing and aerodynamics of /h/ produced by women, men, and children
Authors: Koenig Laura L. , McGowan Richard S.
Published: October 2005

Patterns of consonantal voicing, especially as measured by voice onset time (VOT), have played an important role in discussions of speech timing control across populations. For example, relatively late acquisition of adultlike VOT values for voiceless aspirated stops in normal children has been attributed to the precise laryngeal-oral phasing required for these sounds. Implicit in such arguments is the assumption that the laryngeal and oral events themselves are comparable across subject groups. The present study attempts to assess the validity of this assumption in normal English-speaking women, men, and 5-year-old children. Recordings of oral airflow, intraoral air pressure, and acoustics were made as subjects produced a variety of voiceless consonants in prestress position within a carrier phrase. Analysis here focuses on /h/, which involves no oral obstruction and therefore affords the clearest picture of events at the glottis during the consonant. In these data, the patterns of flow increase, voicing offset and voicing onset during abduction for /h/ show certain differences across groups and suggest that some aspects of laryngeal behavior are not identical across these populations. Results are discussed in terms of group-related differences in anatomy and aerodynamic quantities.
On measuring native Japanese speakers’ sensitivity to English /r/–/l/ contrast in a one-interval identification task with confidence ratings
Authors: Takagi Naoyuki
Published: October 2005

The validity of applying the signal detection theory (SDT) in measuring native Japanese listeners’ sensitivity to large sets of English /r/ and /l/ tokens was tested in a one-interval identification task with confidence ratings. Two distinct sets of 200 tokens (100 /r/’s and 100 /l/’s produced by ten native English talkers) were used for each of the positions in which the target consonants appeared (i.e., word initial and consonant cluster). The response patterns of all 20 subjects (10 for word initial, 10 for cluster positions) except one in the word initial condition were consistent with the prediction of SDT, indicating that the application is valid for the majority of Japanese listeners. The two distinct sets of stimuli for each position condition, however, did not lead to identical results, reflecting strong observer–stimulus interaction. Reliability of this sensitivity estimation was also confirmed by comparing two blocks of presentations (200 trials each) for each stimulus set. The present paradigm thus offers a valid and reliable method of estimating native Japanese listeners’ sensitivity to a given large set of English /r/ and /l/ tokens. The underlying mathematical model of SDT and the interpretation of its statistics such as da (sensitivity) and ca (response bias) are shown.
Voice onset time of Japanese and English stop consonants uttered by the returnees (Japanese–English bilinguals)
Authors: Nakashima Hirotake
Published: October 2005

The present study deals with the speech production by bilinguals in both languages. The objective speech sounds are Japanese and English stop consonants. Japanese stop consonants are very similar to English ones, but is is well-known that the voice onset time of stop consonants for both languages are different from one another. The aim of this study is to examine the voice onset time of Japanese and English stop consonants uttered by the returnees (Japanese–English bilinguals) under the different linguistic circumstances. It was found that there were three types for the returnees in the production of stop consonants. These results are compared with those of Japanese who learned English.
Articulatory and acoustical characteristics of lateral misarticulation in Japanese
Authors: Suzuki Noriko , Fujita Yukihiro , Michi Ken-ichi , Akagi Masato , Kitamura Tatsuya
Published: October 2005

Lateral misarticulation (LM) is a type of misarticulation in which the tongue dorsum contacts the hard palate continuously, forcing air out from the retromolar region to the buccal groove. To discuss the relationship between this articulatory gesture and acoustical characteristics, physiological experiments and acoustic analyses were performed during the production of sustained |sh| in functional articulation disorders and cleft palate misarticulation. Electropalatography, lateral radiographic film examination, and airflow measurements were used to analyze physiological features. Speech samples were analyzed using the improved cepstrum method to observe acoustical features. The following results were obtained: (1) The tongue dorsum maintained broad contact with the hard palate during LM production. (2) Air flow was directed from one side of the posterior region of the hard palate. (3) The spectral envelopes of the LM are flat in the frequency band above around 4000 Hz, whereas normal speech has a plateau. Moreover, there is a substantial peak around 3.2 kHz in the LM which varies with time, a variation not present in normal speech.
The glottal contrast in Babine/Witsuwit’en
Authors: Davis Katharine , Hargus Sharon
Published: October 2005

Babine/Witsuwit’en, an Athabaskan language, has been said to have a phonemic contrast between voiceless unaspirated, voiceless aspirated, and ‘‘glottalized’’ stops. A study of alveolars in initial position [K. Davis and S. Hargus, J. Acoust. Soc. Am. 96, 3348(A) (1994)] found that B/W has three types of ‘‘glottalized’’ consonant production: a classic ejective type, a type distinguishable only by lowered F0, and a type indistinguishable from the voiceless unaspirate. Speaker-dependent production type variation was proposed to be indicative of a sound change in progress. The present study investigates the same contrast in intervocalic position. Field recordings of ten native speakers were measured for closure duration, VOT, and the F0 of the following vowel. Many exemplars in the present study exhibited voicing during closure; depending on the speaker, this was true for stops in one, two, or all three phonemic categories. It was also found that some subjects produced a classic ejective with silent period after the burst and some did not. For all speakers, however, significantly lowered F0 and significantly longer VOTs were consistent indicators of the ‘‘glottalized’’ stops. Intervocalic data from additional speakers may yet reveal speaker-dependent neutralization, as was found in the case of initial stops. [Work supported by NSF.]
Velic and lingual articulations are affected by prosodic position for consonants but not vowels in French
Authors: Fougeron Cecile
Published: October 2005

This study investigates the effect of position-in-prosodic-domain on the velic and lingual articulation of French consonants and vowels. The segments were placed in five different prosodic positions: Utterance-initial, intonational phrase-initial, accentual phrase-initial, word-initial, and syllable-initial. Nasal airflow (considered as an indirect measurement of velum articulation) was recorded for [n] and the open nasal vowel [■] for four French subjects. Using electropalatography, linguopalatal contact was recorded for the dental consonants [n] and [t] and for the closed vowel [i] for two French subjects. Results show that consonants that are initial in a higher prosodic domain have more linguopalatal contact and less nasal flow. Moreover, more positions are distinguished by variation in linguopalatal contact than in nasal airflow. Results for vowels show that prosodic positions are distinguished by nasal airflow for only one speaker, and by linguopalatal contact for none of the speakers. Thus position-in-prosodic-domain can affect the articulation of two remote articulators but, at least for the articulators studied, the effect is restricted to consonant articulation. [Work supported by NSF.]
Phonetic evidence for the phonological status of the tense–lax distinction in German
Authors: Kroos Christian , Hoole Philip , Kühnert Barbara , Tillmann Hans-G.
Published: October 2005

Recently [Hoole et al., Proc. ICSLP 94, 1, 53–56 (1994)] a comparison was made with EMMA of the kinematic properties of German tense and lax vowels over changes in speech rate. They appeared not to differ in the internal organization of the elementary CV and VC movements, but the lax vowels showed tighter serial coupling of CV to VC movement. These results were expected given the strong phonological tradition (on a phonetically elusive substrate) of accounting for the differences between these vowels at the level of word prosody (especially in the link between vowel and following consonant). Nevertheless, important questions remain open: First, analysis of the velocity profiles of the CV and VC movements had been based on a parameter (ratio of peak to average velocity) that may not capture all relevant differences. Second, it was unclear whether tense–lax differences are equally clear-cut for all vowel subcategories (e.g, high, low, rounded, unrounded) and also for different consonantal contexts. The more refined and extensive analyses now carried out will be used to assess the well-foundedness of the earlier preliminary conclusions and to place the German results within the wider perspective of improved understanding of vowel-system typologies. [Work supported by German Research Council.]
Effects of place of articulation and first formant onset properties on voicing judgments
Authors: Benki Jose R.
Published: October 2005

The categorization of voiced and voiceless syllable-initial stops is dependent primarily on voice onset time (VOT), but has been proposed to be sensitive to first formant (F1) transitions and place of articulation. The present study tested the effect of both F1 transition and place cues on the categorization of voiced and voiceless stops in a /■Ca/ context (second syllable stress). Three different stop properties were independently manipulated: VOT, F1 onset frequency, and place of articulation. VOT was varied along a 0 to 65-ms continuum. Four different F1 onset frequencies for the /Ca/ transition were used. Place (labial, alveolar, and velar) was cued by both the release burst and higher formant transitions into and out of the stop. The effects of F1 transition and place on voicing judgments were measured by shifts in the VOT identification boundary. The effect of F1 on voicing judgments would be interpreted as resulting from a general mechanism of audition nonspecific to speech, following Kluender [J. Acoust. Soc. Am. 90, 83–96 (1991)] who found that categorization of burstless CV stimuli from a VOT continuum is sensitive to F1 onset frequency, but not place. In contrast, an effect of place on voicing judgments would be interpreted as the result of a phonological category determining phonetic criteria, in this case place determining VOT thresholds.
The level of perceptual integration of place of articulation of nasal consonants from short duration segments
Authors: Ohde Ralph N. , Vause Nancy L.
Published: October 2005

Recent findings [R. N. Ohde and A. H. Perry, J. Acoust. Soc. Am. 96, 1303–1313 (1994); R. N. Ohde and M. T. Ochs, J. Acoust. Soc. Am. (in press)] indicate that a peripheral mechanism may be involved in processing spectral discontinuities from the nasal murmur to vowel onset. The purpose of the current study was to assess the level of perceptual integration of nasal consonants. The speech sample was comprised of CV syllables produced by an adult female and male, and consisted of either [m] or [n] in the context of four vowels [i æ u ■]. Twelve adults identified the place of articulation of the nasal before and after the insertion of periods of silence ranging from 0 to 1000 ms between murmur and vowel transition segments of varying duration. In the experimental conditions, the murmur and the vowel were split and presented to different ears. The major findings were as follows: (1) Perceptual integration was significantly greater for the murmur + transition presented monaurally with a 0-ms gap duration than the comparable split channel condition; and (2) across the split channel conditions, identification of place of articulation of the nasal was near chance level (50%). The results support the conclusion that a major component of the observed perceptual integration effect is based on a peripheral mechanism. [Work supported by NIH and a Vanderbilt University Research Council Grant.]
Speech perception for hearing aid users versus cochlear implantees
Authors: Flynn Mark C. , Dowell Richard C. , Clark Graeme M.
Published: October 2005

Recent improvements in speech recognition for profoundly deaf cochlear implant patients have suggested that some severely hearing-impaired people would be more successful with a cochlear implant than a hearing aid. In order to investigate this possibility, a detailed investigation of the aided speech perception performance of people with severe hearing losses (n=30) was conducted. Speech recognition tests included 24 consonant recognition, 11 vowel recognition, CNC words, CUNY sentences, and the Connected Speech Test. Significant correlations (p<0.01) were found between pure-tone thresholds and speech recognition test results. A large proportion of the variance in the scores was not accounted for by this factor. Other factors, such as the configuration of the hearing loss, type of pathology, use of contextual cues, and age will be discussed. Comparisons of mean scores were made between the group of severely hearing-impaired people and a comparable group of multiple channel cochlear implant users. It was found that the severely hearing-impaired group performed better (p<0.01) than the group of cochlear implant users in the consonant, vowel, and word recognition tasks. Conversely, in assessments of sentence recognition the cochlear implant group performed better (p<0.01) than the group with severe hearing impairment.
Relational perception of formants and stop consonants: Evidence from missing first formant stimuli
Authors: Govindarajan Krishna K.
Published: October 2005

If the first formant (F1) is missing, does the listener treat the second formant (F2) as the effective ‘‘F1’’ or does he/she substitute a default value for F1? Is stop consonant identification dictated by relational or absolute formant frequencies (e.g., locus theory)? To answer these questions, an experiment was carried out in which subjects identified synthetic consonant–vowel (CV) stimuli whereF 1 had a transition that rose into the vowel, had no transition (i.e., a flat transition), or was absent. Listeners identified stimuli with a rising F1 transition as either /ba/ or /da/ depending on the F2 transition, and stimuli with no F1 transition as /a/. For stimuli where F1 was absent and F2 had a rising transition, listeners perceived either /ba/ or /da/ depending on the F3 transition; and for stimuli with F1 absent and no F2 transition, listeners perceived /a/. Thus preliminary findings suggest that when F1 is missing, subjects do indeed treat F2 as ‘‘F1,’’ and respectively, F3 as ‘‘F2,’’ leading to the conclusion that stop consonant identification is not dictated by absolute formant frequencies, but uses relative measures. The results have implications for models of stop consonant perception. [Work supported by NIH grant DC00194-02.]
Categorical perception of [ba] and [pa]: Integration of acoustical cues
Authors: Slawinski Elzbieta B. , Lau Nhan L.
Published: October 2005

Multiple acoustical cues contribute to the perceptual distinction of many phonetic contrasts. For example, the basic and dominant phonetic correlate of the phonemic (voiced) contrast in stop consonants in word-initial position is the duration of voice onset time (VOT). However, as analysis of production data shows, voiced and voiceless stop consonants vary also in the intensity of a noise burst. The reported study focused on changes in the categorical perception of initial stop consonants [ba] and [pa]. Twenty-eight young adults with normal hearing (better than 10 dB HL) participated in the experiment. Ninety-nine syllables ranging from [ba] to [pa], and which varied in both the VOT and intensity of initial burst, were synthesized on a NEXT computer. Participants were asked to categorize 792 tokens into [ba] and [pa] categories. Results indicate that listeners relied on available cues in different ways. Thus listeners could be divided into two groups: those who used the intensity of burst in their categorization and those who relied exclusively on VOT. Those who integrated information about both acoustical cues did so especially within the ambiguity range.
The relative perceptibility of initial and final consonants
Authors: Redford Melissa A. , Diehl Randy L.
Published: October 2005

Syllable inventories allowing only initial consonants predominate over those allowing both initial and final consonants in the world’s languages. One possible explanation may be that final consonants are less perceptually salient than initial consonants. In this study the perceptibility of final consonants was examined relative to initial consonants. The relative perceptibility of final consonants preceding word initial consonants compared with those preceding word initial vowels was also examined. Fourteen subjects were presented with 147 different nonsense CVC syllables spoken by four talkers in two frame sentences in −15 dB S/N. Subjects were asked to write down the nonsense syllable that occurred in each frame sentence. Results indicated that initial consonants were significantly more perceptible than final consonants (p=0.0002) and that final consonants which preceded a word initial vowel were significantly more perceptible than those that preceded a word initial consonant (p=0.0001). Subsequent analyses of the nonsense syllable stimuli suggest that the relative perceptual status of initial and final consonants is partially attributable to differences in production. The findings from this study are consistent with the idea that syllable inventories in the world’s languages are influenced by perceptual factors. [Work supported by an NSF Fellowship and NIH.]
Asymmetries in consonant confusion
Authors: Plauché Madelaine , Delogu Cristina , Ohala John J.
Published: October 2005

Both historical sound change and laboratory confusion studies show strong asymmetries of consonant confusions. Historically [ki] commonly changes to [t∫i] (e.g., English chill, cognates with cool), but not the reverse. Similarly, Winitiz et al. [J. Acoust. Soc. Am. 51, 1309–1317 (1972)] in a consonant confusion study, found [ki] confused with [ti] more often than the reverse. It is hypothesized that such asymmetries arise when two sounds are acoustically similar except for one or more differentiating cues, which cues are subject to a highly directional perceptual error. For example, if soundx possesses a cue that y lacks, listeners are more likely to miss that cue than introduce it spuriously. /k/ and /t/ before /i/ have similar formant transitions but differ in their burst spectra: /k/ has a sharp mid-frequency peak that /t/ lacks. Listeners are more likely to miss the spectral peak for /k/ than introduce it in the burst of /t/. These consonant confusion studies of Italian syllables support this hypothesis: Italian listeners confused /ki/ with /ti/ with increasing asymmetry when the S/N ratio increased (where noise masks the burst more than the formant transitions) and when the burst was excised completely. Implications for phonetic theory and speech technology will be discussed.
Acoustic correlates of segmentalized speech patterns in motor speech disorders
Authors: Tjaden Kris
Published: October 2005

It has been argued that principles of gestural-based speech production theory may account for speech production aberrancies in motor speech disorders (MSDs) [Weismer et al., J. Phon. 23, 111–126 (1995)]. In the present study, four individuals with MSDs exhibiting segmentalized speech patterns (e.g., perceptual impression of speech being ‘‘metered out’’ segment by segment) and four controls produced CV words in carrier phrases at fast and habitual rates. Degree of gesture overlap was indexed by F2 onset frequency. Descriptive measures ofF 2 onset were used to evaluate whether segmentalized speech patterns in MSDs were associated with reduced gesture overlap in comparison to controls. Temporal variability in F2 formant trajectories for all speakers was modeled as the mutual sliding of adjacent gestures using regression analyses. Three disordered speakers showed evidence of reduced overlap for targets produced at habitual rates in comparison to controls; this difference generally was maintained at fast rates. For all speakers, fast rates were associated with reductions in both gesture magnitude and overlap relative to habitual rates. Regression analyses suggested that temporal variability in F2 trajectories of select targets produced at habitual rates may be modeled as the mutual sliding of gestures. Individual differences and stimuli effects are discussed.
Perception of lateral misarticulation and its physical correlates
Authors: Akagi Masato , Kitamura Tatsuya , Suzuki Noriko , Michi Ken-ichi
Published: October 2005

To discuss the relationship between perceptual diagnosis of lateral misarticulation (LM) by sophisticated listeners and its physical correlates, two experiments using continuous speech /■/ were performed. Experiment 1 was a comparison of the spectral envelopes of normal speech /■/ with those of LM. Experiment 2 was the detection of similarities based on auditory impressions of sophisticated listeners between LM and normal speech /■/ with specific spectral envelope bands replaced. The stimuli for experiment 2 were resynthesized from modified spectral envelopes by using the LMA synthesizer. These experiments showed the following. (1) Spectral envelopes of the LM are flat in the frequency band above approximately 4 kHz, whereas normal speech presents a plateau. Moreover, there is a substantial peak around 3.2 kHz in the LM, which varies with time almost periodically, a variation not present in normal speech. (2) The replacement of the spectral envelope between 2.5 and 4.5 kHz of normal continuous speech with that of LM resulted in a remarkable increase in similarity to LM based on auditory impressions. These facts suggest, that the spectral envelope characteristic of the LM is a near-periodical variation around 3.2 kHz.
Vowel perception in 3- and 4-year-old children
Authors: Ohde Ralph N. , Haley Katarina L.
Published: October 2005

The purpose of this study was to assess the perceptual role of brief synthetic consonant–vowel syllables as cues for vowels in children and adults. The [d] and [g] stop-consonants were synthesized in the context of three vowels, [i u ■], with durations of 10, 30, or 46 ms. These syllables were produced with bursts, and contained formant motions and/or formant onset frequencies appropriate for each stop-consonant place of articulation. Ten adults and ten children in both of the age groups, 3 and 4 years, were trained to identify the vowel as either /i/, /u/, or /■/. The results revealed the following major findings: (1) Across consonant context, vowel identification by adults was significantly higher than vowel identification by 3- and 4-year-olds, and 4-year-olds were significantly higher than 3-year-olds; (2) Vowel identification was significantly higher at each level of duration for the 3-year olds, and the two longer-duration stimuli, were significantly different from the shorter stimulus for the 4-year-olds; and (3) The 3- and 4-year-olds generally identified the high vowels, [i u], at a significantly higher level than the low vowel, [■]. The results support the conclusions that vowel perception in young children interacts with stimulus duration and vowel quality, and that dynamic formant motion is no more important for young children than for adults. [Work supported by NIH and a Vanderbilt University Research Council Grant.]
Stereo acoustic echo cancellation: A review
Authors: Sondhi M. Mohan , Morgan Dennis R. , Benesty Jacob , Hall Joseph L.
Published: October 2005

Adaptive echo cancelers have been used successfully for over a decade to combat echoes that arise on a telephone network due to mismatches in impedance at various points in the circuit. Echoes arise in teleconferencing too, due to coupling between the loudspeaker and microphone in each room. This problem is similar to the network echo problem, although the impulse responses are longer and can change more rapidly. When echoes arise in a stereophonic system, however, the problem changes character due to an inherent nonuniqueness in estimating the echo paths. In this talk we will review the current status of the problem of stereo echo cancellation. After a brief introduction to the general problem of echo control, the nonuniqueness mentioned above will be discussed and then several approaches will be described to get around this nonuniqueness. At present echo path responses can be matched with an error of less than −20 dB, without any loss of the stereophonic effect.
Noise reduction for a sub-band acoustic echo canceller
Authors: Sasaki Junko , Haneda Yoichi , Makino Shoji
Published: October 2005

Noise reduction without speech distortion, which is combined with a sub-band acoustic echo canceller in hands-free communications, is proposed. In this method, ambient noise is suppressed by using each sub-band’s loss that is adaptively determined based on three conditions: the ratio of the current signal level to the estimated noise level (SNR), previous loss levels, and neighboring sub-band SNRs. The loss level is determined by smoothing out the current loss level and previous ones, where the current loss level is calculated from the sub-band’s SNR and neighboring sub-band SNRs. Consequently, this method has no ‘‘musical noise’’ due to time-varying loss levels. The noise level used in the calculation of SNR is estimated for each sub-band by maintaining histograms that show the level distribution of the sub-band signals. In addition, this estimated noise level is used simultaneously with the echo signal level to control the affine projection algorithm in a sub-band echo canceller. Using both signal levels, the adaptive algorithm can maintain a stable echo return loss enhancement for small far-end signals. The proposed noise reduction is evaluated in a 32-sub-band echo canceller. It is shown that transmission signals become clearer after reducing echo and ambient noise.
Design of a filter matrix used for stereo dipole transaural systems
Authors: Hamada Hareo , Tokunou Hironori , Watanabe Yuko , Kirkeby Ole , Nelson Philip A.
Published: October 2005

A new transaural system, referred to as the ‘‘stereo dipole’’ reproduction system (hereafter the SD system), using a closely spaced pair of loudspeakers in front of a listener, has been introduced recently. In this paper, the deconvolution techniques used in the SD system, in which a 2×2 matrix of digital filters is used to compensate for the response of the loudspeakers and to create virtual sound sources, are dealt with. The deconvolution method is based on the analysis of a matrix of exact least-squares inverse filters. Two kinds of design techniques are developed. One is a very fast FFT-based deconvolution method; the other is a time-domain counterpart to the FFT method. The well-known principles of least-squares optimization and regularization are introduced in both the design methods. The relationships between the characteristics of the deconvolution filters and loudspeaker arrangement are investigated. In particular, the theoretical analysis is concerned with the locations of poles and zeros and the required dynamic range of the filter. Computer simulation reveals that the SD system offers the robustness of the sound image and a wide range of equalization area relative to the ordinary loudspeaker arrangement system. Finally, the subjective effects of the filter characteristic are also discussed.
Adaptive noise cancellation with directional microphones
Authors: Elko Gary W.
Published: October 2005

The use of adaptive noise cancellation in communication devices has now been under investigation for more than two decades. Early studies predicted large SNR gains that were rarely obtained when actual devices were tested in typical acoustic noise environments. One of the problems encountered was the lack of coherence between the ‘‘noise’’ sensor and the actual corrupting noise signal. The measured low coherence values were most probably due to time-varying multipath, multiple uncorrelated noise sources, and nonlinearities in the signal and noise transmission paths. This talk will address the expected noise cancellation that can be obtained by using directional microphones to spatially filter the acoustic field into signal-plus-noise and noise channels. Analytical results for spherically and cylindrically isotropic noise fields will be shown and discussed.
Automated evaluation of acoustic talker direction finder algorithms in a computer-controlled varechoic chamber
Authors: Morgan Dennis R. , Parikh Vipul N.
Published: October 2005

Acoustic talker direction finders have potential applications to camera pointing for teleconferencing and microphone array beam steering for suppressing reverberation in all types of communication and voice processing systems. This paper describes a laboratory setup and computer interface that was developed for testing talker direction finder algorithms in the Bell Labs varechoic chamber, which is a room with computer-controlled absorbing panels. The procedure utilizes the full capability of the facility by automatically stepping through a sequence of room panel configurations, outputting a digital speech signal, running the processor, and collecting the data. The advantage of this technique is that it allows for testing under a multitude of different acoustic conditions in the same physical location, thereby enabling a general characterization of the algorithm under evaluation.
Estimation of wavefront arrival delay for acoustical signals using the cross-power spectrum phase technique
Authors: Rabinkin Daniel V. , Renomeron Richard J. , Flanagan James L. , French Joseph C.
Published: October 2005

In order to provide spatially selective sound capture in a teleconferencing environment, microphone array systems require accurate determination of the location of the desired source. Sound source location in turn relies on estimating time delay of arrival (TDOA) of a sound wavefront across a given microphone sensor pair. The cross-power spectrum phase (CPSP) method [M. Omologo and P. Svaizer, ICASSP 94] may be used for TDOA estimation. It is desirable to operate microphone array systems in untreated acoustical environments. Such an environment may produce multipath sound propagation and may contain moderate sources of interfering noise. The TDOA estimates computed using CPSP may become unreliable in such an environment. A strategy is presented to extract reliable TDOA information from the CPSP algorithm. The following measures are included: spectral weighting of the CPSP function based on knowledge of noise and sound source statistics, measuring the accuracy of the CPSP function by examining its shape, and evaluating the CPSP only when the captured signal has appropriate energy and spectral characteristics. This strategy enables less error-prone performance, and allows more effective utilization of computing resources in a constrained real-time system. Simulation and real-time results are presented to demonstrate system improvement.
The study of sound field control using reproduction of plane-wave sound
Authors: Miyahara Takeshi , Hamada Hareo
Published: October 2005

A system for teleconferences using a medium-size screen with 3-D sound reproduction having proper incoming direction of the talker’s speech by using the wavefront reproduction technique is discussed. In the ordinary configuration, the multiple loudspeakers are spanned in front of the screen. Therefore, it is expected to reproduce desired wavefronts by a small number of loudspeakers. The number of loudspeakers may depend on the sizes of the screen and service area for the listeners. On the other hand, the sizes of the filter coefficients of the equalizer are also very important to simplify the system configuration, in particular, the capability of computation tasks of the digital signal processor. In this paper, the simulations and the experiments on the wavefront reproduction from the viewpoint of number and location of the loudspeakers and filter for the equalizer were demonstrated. The experimental results, in which the achievements on retrieving the original wavefront are evaluated, will be very useful in constructing the actual system.