This study was designed as a replication and extension of the classic study of vowel acoustics by Peterson and Barney (PB) [J. Acoust. Soc. Am. 24, 175–184 (1952)]. Recordings were made of 50 men, 50 women, and 50 children producing the vowels /i, i, eh, ae, hooked backward eh, inverted vee), a, open oh, u, u/ in h–V–d syllables. Formant contours for F1–F4 were measured from LPC spectra using a custom interactive editing tool. For comparison with the PB data, formant patterns were sampled at a time that was judged by visual inspection to be maximally steady. Preliminary analysis shows numerous differences between the present data and those of PB, both in terms of average formant frequencies for vowels, and the degree of overlap among adjacent vowels. As with the original study, listening tests showed that the signals were nearly always identified as the vowel intended by the talker.

Acoustic characteristics of American English vowels

In this article the author proposes an episodic theory of spoken word representation, perception, and production. By most theories, idiosyncratic aspects of speech (voice details, ambient noise, etc.) are considered noise and are filtered in perception. However, episodic theories suggest that perceptual details are stored in memory and are integral to later perception. In this research the author tested an episodic model (MINERVA 2; D. L. Hintzman, 1986) against speech production data from a word-shadowing task. The model predicted the shadowing-response-time patterns, and it correctly predicted a tendency for shadowers to spontaneously imitate the acoustic patterns of words and nonwords. It also correctly predicted imitation strength as a function of "abstract" stimulus properties, such as word frequency. Taken together, the data and theory suggest that detailed episodes constitute the basic substrate of the mental lexicon. Early in the 20th century, Semon (1909/1923) described a memory theory that anticipated many aspects of contemporary theories (Schacter, Eich, & Tulving, 1978). In modem parlance, this was an episodic (or exemplar) theory, which assumes that every experience, such as perceiving a spoken word, leaves a unique memory trace. On presentation of a new word, all stored traces are activated, each according to its similarity to the stimulus. The most activated traces connect the new word to stored knowledge, the essence of recognition. The multiple-trace assumption allowed Semon's theory to explain the apparent permanence of specific memories; the challenge was also to create

/pdf/echoes-of-echoes-an-episodic-theory-of-lexical-access-4u3ubhcqbh.pdf

Echoes of echoes? An episodic theory of lexical access.

On the quantal nature of speech

http://jimflege.com/files/Flege_Bohn_effect_experience_JP_1997.pdf

Effects of experience on non-native speakers' production and perception of English vowels

During speech perception, linguistic elements such as consonants and vowels are extracted from a complex acoustic speech signal. The superior temporal gyrus (STG) participates in high-order auditory processing of speech, but how it encodes phonetic information is poorly understood. We used high-density direct cortical surface recordings in humans while they listened to natural, continuous speech to reveal the STG representation of the entire English phonetic inventory. At single electrodes, we found response selectivity to distinct phonetic features. Encoding of acoustic properties was mediated by a distributed population response. Phonetic features could be directly related to tuning for spectrotemporal acoustic cues, some of which were encoded in a nonlinear fashion or by integration of multiple cues. These findings demonstrate the acoustic-phonetic representation of speech in human STG.

/pdf/phonetic-feature-encoding-in-human-superior-temporal-gyrus-2e1sw7f1so.pdf

Phonetic feature encoding in human superior temporal gyrus

A quantitative perceptual model of human vowel recognition based upon psychoacoustic and speech perception data is described. At an intermediate auditory stage of processing, the specific bark difference level of the model represents the pattern of peripheral auditory excitation as the distance in critical bands (barks) between neighboring formants and between the fundamental frequency (F0) and first formant (F1). At a higher, phonetic stage of processing, represented by the critical bark difference level of the model, the transformed vowels may be dichotomously classified based on whether the difference between formants in each dimension falls within or exceeds the critical distance of 3 bark for the spectral center of gravity effect [Chistovich et al., Hear. Res. 1, 185–195 (1979)]. Vowel transformations and classifications correspond well to several major phonetic dimensions and features by which vowels are perceived and traditionally classified. The F1–F0 dimension represents vowel height, and high vo...

A perceptual model of vowel recognition based on the auditory representation of American English vowels.

Vowel duration is influenced both by speaking rate and by voicing of the postvocalic consonant. Our study systematically investigates how these two factors interact. Syllable and segment durations were measured for /pVC/ target syllables containing one of eight vowels and voiced or voiceless stops or fricatives. Target syllables were produced in sentence contexts at three speaking rates by four female and three male native American English speakers. Our findings replicate and extend Klatt's incompressibility model of vowel duration [D. H. Klatt, J. Acoust. Soc. Am. 54, 1102–1104 (1973)]. The two factors influencing vowel duration do not combine independently in a multiplicative or additive fashion. Instead, they interact such that vowels manifest a resistance to further shortening.

/pdf/interaction-of-speaking-rate-and-postvocalic-consonantal-5b37dkoec4.pdf

Interaction of speaking rate and postvocalic consonantal voicing on vowel duration in American English

A critical spectral distance of 3 to 3.5 critical bands (bark) between first and second formant frequencies in simplified two‐formant synthetic Russian vowels has been reported by Chistovich and her colleagues. Syrdal [J. Acoust. Soc. Am. Suppl. 1 71, S105 (1982)] transformed fundamental frequency and formant frequency values from naturally produced American English vowels into Bark values from which three distance measures were calculated: F1−F0, F2−F1, and F3−F2. Her proposed auditory‐model of vowel perception reduced between‐speaker variability and provided a perceptually based quantitatively defined link between some acoustic and phonetic features. In the present series of experiments, several synthetic two‐vowel continua were constructed, each with a varying frequency parameter which crossed a critical distance in either of the 3‐bark difference dimensions. Critical distances over the 3‐bark difference dimensions, estimated by phoneme boundaries calculated from vowel identification tests, will be compared with each other and with previous estimates. Some effects of duration on the phoneme boundary estimates of critical distance will also be discussed. [Work supported by NIH].

H. S. Gopal

Papers

A perceptual model of vowel recognition based on the auditory representation of American English vowels.

Interaction of speaking rate and postvocalic consonantal voicing on vowel duration in American English

Perceived critical distances between F1-F0, F2-F1, F3-F2