An acoustic study of the tongue root contrast in Degema vowels.

Degema is an Edoid language of Nigeria whose ten vowels are organized phonologically into two sets of five. The two sets are thought to be differentiated by the degree of tongue root advancing. This paper examines the acoustic nature of these vowels as represented in field recordings of six speakers. The most consistent acoustic correlate of the tongue root contrast was found to be the first formant frequency which consistently distinguishes four of the five vowel pairs, the exception being the two low vowels. Three of the five pairs could also be distinguished by F2, though the direction of the difference was not consistent. Additionally, a comparison of corresponding advanced and retracted vowels using a normalized measure of relative formant intensity demonstrated that this correlate could also distinguish them in general, but only operated reliably in two of the five vowel pairs. The pair of low vowels could not be distinguished from each other by any of these measures. Finally, a perceptual study was conducted which demonstrates that Degema speakers do not classify their vowels very well using formant frequencies as the sole acoustic variable; only the two pairs of mid vowels were reliably singled out by native listeners from an array of synthesized vowels.

Individual differences in vowel production.

It is often assumed that a relatively small set of articulatory features are universally used in language sound systems. This paper presents a study which tests this assumption. The data are x-ray microbeam pellet trajectories during the production of the vowels of American English by five speakers. Speakers were consistent with themselves from one production of a word to the next, but the articulatory patterns manifested by this homogeneous group were speaker specific. Striking individual differences were found in speaking rate, the production of the tense/lax distinction of English, and in global patterns of articulation. In terms of a task-dynamic model of speech production, these differences suggested that the speakers used different gestural target and stiffness values, and employed different patterns of interarticulator coordination to produce the vowels of American English. The data thus suggest that, at some level of speech motor control, speech production tasks are specified in terms of acoustic output rather than spatiotemporal targets or gestures.

Stops in the world's languages.

This account of the great variety of stops in the world's languages shows that, apart from their place of articulation, these sounds can be described principally in terms of the activities that occur at three phases: onset, closure, and release. Other potentially contrastive features discussed include length, and the use of the glottalic airstream mechanism (other airstream mechanisms are not considered here). Phonologically only two phases--closure and release--are exploited; independent distinctions of features such as phonation type or articulatory manner cannot be found in the onset phase. We examine the combinatorial possibilities of the features that are used and discuss implications for phonological feature systems.

A note on "Information conveyed by vowels".

In an early experiment using synthetic speech, it was shown that raising or lowering the formants in an introductory sentence affected the identification of the vowel in a following test word [P. Ladefoged and D. Broadbent, J. Acoust. Soc. Am. 29, 98-104 (1957)]. This experiment has now been replicated using natural speech produced by a phonetician using two different overall settings of the vocal tract.

Cultivation of second and third passage cells from Cercopithecus monkey kidneys in monolayer cultures.

In order to further reduce the amount of monkeys used for production of inactivated poliovaccine without expensive investments, cultivation of second and third passage cells from Cercopithecus monkey kidneys in monolayer cultures has been attempted. Steep growth curves were obtained for all three passages. But the initial loss of cells in the first passage was a problem. Another one was the increased risk of contamination when higher passages of monolayer cultures were used. For practical purposes it may therefore be more favourable to use second instead of third passage cells.

Enzyme-linked immunosorbent assay for detection of poliovirus antigen and antibody.

A sensitive method is described to detect poliovirus antigen in diluted samples of semi-processed and processed Salk vaccine material using a double antibody sandwich enzyme-linked immunosorbent assay (ELISA). The introduction of a simple conjugate-blocking step permits confirmation of antigen specificity and allows evaluation of neutralising antibody concentration in the sera employed as soon as four hours after sample addition.

Generating vocal tract shapes from formant frequencies.

An algorithm that uses only the first three formant frequencies has been devised for generating vocal tract shapes as seen on midsagittal x-ray diagrams of most English vowels. The shape of the tongue is characterized in terms of the sum of two factors derived from PARAFAC analysis: a front raising component and a back raising component. Stepwise multiple regression techniques were used to show that the proportions of these two components, and of a third parameter corresponding to the distance between the lips, are highly correlated with the formant frequencies in 50 vowels. The recovery algorithm developed from these correlations was tested on a number of published sets of tracings from x-ray diagrams, and appears to be generalizable to other speakers.