Robert F. Port

Cross-Language Phonetic Interference: Arabic to English.

This study compares phonetic implementation of the stop voicing contrast produced in Arabic by Saudi Arabians and by both Americans and Saudis in English. The English stops produced by Saudis manifested temporal acoustic correlates of stop voicing (VOT, stop closure duration, and vowel duration) similar to those found in Arabic stops. Despite such phonetic interference from Arabic to English, however, American listeners generally had little difficulty identifying the English stops produced by the Saudis, with the exception of /p/. This phoneme, which is absent in Arabic, was frequently produced with glottal pulsing during the stop closure interval. The timing of /p/, however, suggests that the Saudis did grasp the phonological nature of /p/ (i.e., that the contrast between /p—b/ is analogous to that between /t—d/ and /k—g/) but were unable to control all the articulatory dimensions by which this sound is produced.

Meter and speech

Speech is easily produced with regular periodic patterns—as if spoken to a metronome.If we ask what it is that is periodically spaced, the answer is a perceptual ‘beat’ that occurs near the onset of vowels (especially stressed ones).Surprisingly, when periodically produced speech is studied it exhibits attractors at harmonic fractions (especially halves and thirds) of the basic periodicity.It is shown that the Haken–Kelso– Bunz model provides conceptual tools to account for the frequency histogram of acoustic beats in the speech.Why might there be attractors at periodically spaced phase angles? It is hypothesized that there are neural oscillations producing a pulse on every cycle, and that these pulses act as attractors for the beats at the onsets of syllables.Presumably these periodic time locations are generated by the same physiological mechanism as the periodic attentional pulse studied for some years by Jones (Psychol.Rev.96 (1989) 459; Psychol.Rev.106 (1999) 119).We propose that neurocognitive oscillators produce periodic pulses that apparently do several things: (1) they attract perceptual attention; (2) they influence the motor system (e.g., when producing speech) by biasing motor timing so that perceptually salient events line up in time close to the neurocognitive pulses.The consequent pattern of integer-ratio timings in music and speech is called meter.Speakers can control the degree to which they allow these metrical vector fields to constrain their timing.

Consonant/vowel ratio as a cue for voicing in English

Several experiments investigate voicing judgments in minimal pairs likerabid-rapid when the duration of the first vowel and the medial stop are varied factorially and other cues for voicing remain ambiguous. In Experiments 1 and 2, in which synthetic labial and velar-stop voicing pairs are investigated, the perceptual boundary along a continuum of silent consonant durations varies in constant proportion to increases in the duration of the preceding vocalic interval. In Experiment 3, it is shown that speaking tempo external to the test word has far smaller effects on a closure duration boundary for voicing than does the tempo within the test word. Experiment 4 shows that, even within the word, it is primarily the preceding vowel that accounts for changes in the consonant duration effects. Furthermore, in Experiments 3 and 4, the effects of timing outside the vowel-consonant interval are independent of the duration of that interval itself. These findings suggest that consonant/vowel ratio serves as a primary acoustic cue for English voicing in syllable-final position and imply that this ratio possibly is directly extracted from the speech signal.

Effects of timing regularity and metrical expectancy on spoken-word perception.

Certain types of speech, e.g. lists of words or numbers, are usually spoken with highly regular inter-stress timing. The main hypothesis of this study (derived from the Dynamic Attending Theory) is that listeners attend in particular to speech events at these regular time points. Better timing regularity should improve spoken-word perception. Previous studies have suggested only a weak effect of speech rhythm on spoken-word perception, but the timing of inter-stress intervals was not controlled in these studies. A phoneme monitoring experiment is reported, in which listeners heard lists of disyllabic words in which the timing of the stressed vowels was either regular (with equidistant inter-stress intervals) or irregular. In addition, metrical expectancy was controlled by varying the stress pattern of the target word, as either the same or the opposite of the stress pattern in its preceding words. Resulting reac-tion times show a main effect of timing regularity, but not of metrical expectancy. These results suggest that listeners employ attentional rhythms in spoken-word per-ception, and that regular speech timing improves speech communication.

Fractally configured neural networks

Abstract A model is described for one method of instantiating constraints in neural networks, such as are required to account for nativist assertions in an associationist context. An implementation, inspired by some of the processes of biological development, is presented for the construction of networks with such constraints. This implementation, which generates fractally configured neural networks, is investigated by applying it to a simple generalization problem.

Temporal Compensation and Universal Phonetics

Two experiments were conducted, on Japanese and on Arabic, to explore the extent to which vowels adjacent to longer and shorter apical consonants would compensate for the consonant durations. In the A

Representation and recognition of temporal patterns

How can a nervous system represent for itself the temporal relations of patterns that it knows? In order to label auditory patterns, the nervous system must store early portions in order to identify the whole. Both linguists and engineer-scientists have a similar need to record spoken words. This paper reviews three basic models for handling the information-collection problem that supports pattern recognition, whether by scientists or others. Many of these techniques have been implemented in connectionist networks. In linguistic models for words, there are only ordered symbols, i.e. either phonemic segments or words. In engineering and speech science, time windows are built that store the entire signal and allow parametric description of time. But such windows are not plausible for nervous systems. A third alternative is a memory in the form of a dynamic system. These models are driven through a trajectory in state space by the input signals. Thus, the recognition process for familiar patterns produces a ...

Neural representation of temporal patterns

Papers from the April 1993 workshop present findings on questions related to temporal pattern representation and discuss possible future strategies for studying temporal pattern analysis, detailing the many approaches to the representation of time-varying information in the nervous system. Contains

Language as a Social Institution: Why Phonemes and Words Do Not Live in the Brain

It is proposed that a language, in a rich, high-dimensional form, is part of the cultural environment of the child learner. A language is the product of a community of speakers who develop its phonological, lexical, and phrasal patterns over many generations. The language emerges from the joint behavior of many agents in the community acting as a complex adaptive system. Its form only roughly approximates the low-dimensional structures that our traditional phonology highlights. Those who study spoken language have attempted to approach it as an internal knowledge structure rather than as a communal institution or set of conventions for coordination of activity. We also find it very difficult to avoid being deceived into seeing language in the form employed by our writing system as letters, words, and sentences. But our writing system is a further set of conventions that approximate the high-dimensional spoken language in a consistent and regularized graphical form.

Neutralization of obstruent voicing in german is incomplete

A familiar phonological neutralization rule is the merger of voiced and voiceless obstruents in syllable‐final position in German. Thus, the /d/ in Leid ‘sorrow’ is pronounced [‐voice] like the /t/ in leit ‘lead.’ A spectrographic test of minimal pairs by nine Germans, however, revealed (1) vowels before underlying voiced consonants were 10% longer than before underlying voiceless ones, (2) there was a slightly longer interval of glottal pulsing into the consonant closure for the underlying voiced consonants, yet (3) consonant closure durations were the same. Since these consonants all sounded voiceless to us, a listening test was performed. Native speakers of German listened to these utterances and indicated which word of the minimal pair was heard. Subjects were able to guess the intended word about 70% correct—significantly better than chance. This “semicontrast” must be nearly useless in conversation. These results show that voicing neutralization is only partially achieved in German and disprove any ...