This study investigated the effects of lengthened transitions on the perception of stop consonants.  In experiment I, three continua representing the phonetic categories [da] and [ga] containing transitions of 45, 95, or 145 ms were presented to 20 subjects for both labeling and discrimination.  results indicated that although there was a significant change in identification performance from 95 to 145 ms, the shape of the functions, and the locus and slope of the phonetic boundary did not significantly vary across transition lengths.  In addition, discrmination of within-category stimulus comparisons was significantly better at the 95-ms transition length than at 45 or 145 ms.  In experiment II, the availability of acoustic information was investigated further with the adaptation paradigm.  Eight subjects labeled the 45-ms series before and after adaptation with 45-, 95-, and 145-ms [da] stimuli.  No effect of transition length was found. These results suggest that the slope of duration of formant transitions seem to contribute minimally to the perception of place of articulation in stop consonants.

Abstract: "Fundamental frequency in the speech of infants and children" (1978)

Fundamental frequency ranges of six normal infants and children from 33 to 169 weeks were determined by narrow-band spectrographic analysis.  Fundamental frequency values ranged from 30 to 2500 Hz, well outside the values reported in previous studies of noncry utterances.  The use of fey, modal, and high registers is also discussed.

Abstract: A Phonetic Study of a Voicing Contrast in Polish (1979)

    A series of experiments on the production and perception of the voicing contrast in Polish was carried out to determine the importance of the phonetic dimension of Voice-Onset-Time (VOT) in that contrast.  Polish contrasts prevoiced and short-lag VOT categories, while English contrasts short-lag and long-lag VOT categories.  One goal of the study is to explore differences between the two types of contrasts that would account for their relative frequency of occurrence.
    Data was collected for 24 Polish speakers in Wroclaw, Poland.  It was found that the Polish contrast is relatively straightforward in production.  Initial and medial stops in isolated minimal pairs and in running speech styles show no overlap in VOT values between voiced and voiceless stops.  In running speech, voiced closure duration is used as a measure of VOT for voiced stops.  For voiced stops, there is always voicing during closure, while for voiceless stops there is not.  Perceptual experiments were carried out using both synthetic and natural stimuli.  Closure voicing and voicing lag were found to be strong cues for voicedness and voicelessness, respectively; burst voicing is a weaker cue.  However, when synthetic VOT continua are used, listeners' boundaries between the voicing categories are strongly affected by the range of VOT values in each continuum.  Only when the range corresponds to that found in natural Polish productions do the listeners' boundaries align with their production categories. For a range of VOT values corresponding to natural English productions, the Polsih listeners' category boundaries are too high.  On the other hand, American listeners show consistent boundaries on all three synthetic continua, regardless of the VOT range used.  Thus VOT seems to be a less stable perceptual dimension in Polish than in English.  It is proposed that Polish listeners respond to non-Polish ranges of VOT on the basis of psychoacoustic categories, giving the higher boundaries.  The English voicing categories are already aligned with psychoacoustic categories, so American listeners would not show range effects.  Thus the Polish voicing contrast is quite stable in production but less stable in perception.  The reverse is true of the English contrast.
    In medial stops additional cues are shown to enter into a trading relation that determines the percept.  The proportion of closure voicing to closure silence within the total closure duration fo a voiced stop has a perceptual effect that corresponds to the patterns seen in production.  On the other hand, the duration of the preceding vowel, which has been throught to be universally lengthened before voiced consonants, does not correlate with stop voicing in Polish.
    It is proposed that two-category voicing contrasts like those of Polish and English be represented at the phonological level by the feature [+voice] in all languages, so that phonological rules will be expressed equivalently.  At the phonetic level, however, the feature representation would be [n VOT], allowing phonetic detail in each language to be described.  The results of the experiments indicate that VOT is an excellent dimension for such description.

Abstract: "Word duration in early child speech" (1981)

    Word duration in early child speech was examined through a longitudinal study of a set of frequently occurring words for three subjects.  These samples were controlled for phonetic form.  Durations were measured from wide- and narrow-band spectrograms.  Results show that for some words, but not the majority, duration decreased over time; this effect does not appear to be due to increased familiarity with individual lexical items.  Generally, word duration variations within the tested time ranges can be attributed to the effect of position-in-utterance.  From the time a child first combines two words into a single phrase, a nonfinal word will be produced with a shorter duration than it would have in isolation or final position in an utterance.

Abstract: "A cross-language study of range of voice onset time in the perception of initial stop voicing" (1981)

A series of experiments was carried out to compare the extent of range effects in the phonetic categorization of voice onset time (VOT) by speakers of Polish and of Englishk, two languages which contrast different VOT categories.  Results indicate that Poles are more prone to range effects than are Americans.  For acoustic continua with appreciable numbers of prevoiced stimuli, monolingual Polish speakers' perceptual boundaries fall in the gap between their production categories.  For ranges of VOT which include few prevoiced stimuli, their boundaries are substantially shifted.  Americans show no shifts of this type, although they do show some small shifts.  It was determined that the much smaller shifts shown by the American subjects were not due to expectations about the test.  Results are interpreted in terms of the different VOT contrass involved: their spacing along the VOT continuum, and their psychophysical basis.

Abstract: "Patterns in allophone distribution for voiced and voiceless stops" (1983)

Do languages prefer certain types of stop consonants in certain environments?  A survey of 51 languages reveals two general trends.  First, many languages limit the occurrence of final stops; final devoicing is one instance of this phenomenon.  Second, other variation is largely limited to languages whose contrasts in initial position involve short lag vs. long lag VOT; that is, aspiration constrasts.  Among these languages, many sorts of variation are found, which therefore must be described by language-specific rules.

Abstract: "Comments on the jaw and syllable structure" (1983)

In light of a recent proposal by Lindblom (1983) on the relation between phonological sonority and segment coarticulation, various data on jaw movement are discussed.  These data suggest, contrary to Lindblom, that segments do not order themselves according to their propensity to coarticulate.  Rather, the jaw can produce segments in a variety of orders by accommodating those few segments that require a high jaw position while coarticulating other segments. 

Abstract: "Articulatory strengthening at edges of prosodic domains" (1997)

In this paper it is shown that at the edges of prosodic domains, initial consonant and final vowels have more extreme (less reduced) lingual articulations, which are called articulatory strengthening.  Linguopalatal contact for consonants and vowels in different prosodic positions was compared, using reiterant-speech versions of sentences with a variety of phrasings read by three speakers of American English.  Four prosodic domains were considered: the phonological word, the phonological (or intermediate) phrase, the intonational phrase, and the utterance.  Domain-initial consonants show more linguopalatal contact than domain-medial or domain-final consonants, at three prosodic levels.  Most vowels, on the other other hand, show less linguopalatal contact in domain-final syllables compared to domain-initial and domain-medial.  As a result, the articulatory difference between segments is greater around a prosodic boundary, increasing the articulatory contrast between consonant and vowels, and prosodic domains are marked at both edges.  Furthermore, the consonant initial strengthening is generally cumulative, i.e. the higher the prosodic domain, the more linguopalatal contact the consonant has.  However, speakers differed in how many and which levels were distinguished in this way.  It is suggested that this initial strengthening could provide an alternative account for previously observed supralaryngeal declination of consonants.  Acoustic duration of consonants is also affected by prosodic position, and this lengthening is cumulative like linguopalatal contact, but the two measures are only weakly correlated.