Because change happens: 1月 2008

Introduction to Instrumental Phonetics
The field of phonetics can be divided up into a number of sub-fields, and the term 'instrumental' is used to refer to the analysis of speech by means of instruments; this may be acoustic (the study of the physical properties of speech sound, as transmitted between mouth and ear) or articulatory (the study of the way speech sounds are made (‘articulated’) by vocal organs). Instrumental phonetics is a quantitative approach - it attempts to characterise speech in terms of measurements and numbers, rather than by relying on listeners' impressions.
Many different instruments have been devised for the study of speech sounds. The best known technique for acoustic analysis is spectrography, in which a computer produces a "picture" of speech sounds. Such computer systems can usually also carry out the analysis of fundamental frequency for producing "pitch displays". For analysis of articulatory activity there are many instrumental techniques in use, including radiography (X-rays) for examining activity inside the vocal tract, laryngography for inspecting the inside of the larynx, palatography for recording patterns of contact between tongue and palate, glottography for studying the vibration of the vocal folds and many others. Measurement of airflow from the vocal tract and of air pressure within it also give us a valuable indirect picture of other aspects of articulation.
Instrumental techniques are usually used in experimental phonetics, but this does not mean that all instrumental studies are experimental: when a theory or hypothesis is being tested under controlled conditions the research is experimental, but if one simply makes a collection of measurements using instruments this is not the case.
Spectrography
Spectrography is an instrument used in acoustic phonetics which provides a visual representation of the acoustic features that constitute the sounds in an utterance. The original sound spectrograph produced a three-dimensional visual record, or spectrogram, of an utterance, in which time is displayed horizontally, frequently vertically, and intensity by the relative blackness of the marks, on a sheet of sensitized paper. Since the development of acoustic analyses in the late 1940s, the sound spectrograph has been the single most useful device for the quantitative analysis of speech. The early applications of the spectrograph focused on the parameters of normal speaking patterns. Until the mid-1980s most of this research used the electro-mechanical sound spectrograph. The development of digital signal processing or the ability to convert analogue to digital (A/D) signals for analysis has produced radical change in spectrography. Today, spectrographic information can be generated electronically and displayed on a screen.

Electromyography
An introduction to electromyography
Electromyography (EMG) was developed by neurophysiologists, such as Adrian and Bronk (1929) and smith (1934). But it was at the end of World War II, when there was a marked improvement in the technology and electronic apparatus, that EMG began to be used by anatomists, kinesiologists, and clinicians.
EMG is a technique suited to the analysis of skilled movements in general, and of speech movements in particular. It gives the opportunity to study the dynamics of speech production, not only by describing which muscles are contracting and when, but also through revealing the co-articulation of different muscles involved in any one speech gesture. Speech sounds have been described primarily in terms of the position and shapes of the organs of speech, and little attention has been paid to the means by which these are affected. By the 1950s, EMG investigations of speech activity were becoming more common: laryngeal muscles were studied by Faaborg-Anderson (1957), and by Sawashima, Sato, Funasaka and Totsuka (1958); respiratory muscles were investigated by Stetson (1951), and by Draper, Ladeforged and Whitteridge (1959). During the 1960s, EMG was used to study various speech organs, such as the lips (McNeilage 1963; Fromkin, 1966; Lvsaught et al,1961; Ohman, 1967; Ohman et al, 1965), the soft palate (Fritzell 1963; 1969; Lubker, 1968), the tongue (MacNeilage and Sholes, 1964; Smith and Hirano, 1968), and the larynx (Faaborg-Anderson, 1964; Faaborg-Anderson and Vennard, 1964; Hirano et al, 1967). This pioneering electromyographic research into speech production involved single speech organs only. Then, several speech organs were studied at the same time (Sussman et al, 1973). Gay, Ushijima, Hirose and Cooper (1974) recorded EMG from muscles that control the movements of the lips, tongue and jaw. Folkins and Abbs (1975) studied labial compensation for unpredicted jaw loading: EMG activity was measured from three jaw muscles and one lip muscle. Tuller, Harris and Kelso (1982) and Tuller, Kelso and Harris (1982) observed the transformation of articulation, stress and rate using EMG and acoustic data: one lip muscle, one tongue muscle and three jaw muscles were recorded. Alfonso and Baer (1982) investigated the dynamics of vowel articulation: EMG signals were recorded from one lip muscle, one jaw muscle and two tongue muscles. More recently, much attention has been directed towards the interaction among speech muscles, because one muscle contracts in the context of many other opposing or augmenting forces (Folkins, 1981; Gentil and Gay, 1986; Gentil et al, 1983; Hirose, 1977; Honda et al, 1982; Tuller et al, 1981). Speech motor plasticity in the production of a particular spoken utterance, that is variations among a great number of muscles between several subjects, were also evaluated (Gentil, 1992).

EMG on the University of Oklahoma

Electrolaryngography
The eletectrolaryngograph (or simply ‘laryngograph’) is a non-invasive device that has become a standard tool in the Voice Clinic as well as in teaching and research laboratories all over the world. It is used to provide qualitative and quantitative information on vocal fold vibration, and also as the basis of PC-based interactive voice therapy. Electrodes are attached to the neck on each side of the thyroid cartilage, and the vocal cord activity is displayed as traces on a screen. The rise and fall of the fundamental frequency of the vibrations (corresponding largely to the intonation of the voice) can be clearly seen. The technique was developed in the 1970s, and is now widely used in speech science in relation to both normal and abnormal use of the voice.

Speech production and perception tools for real-time assessment, analysis and therapy
Electrolaryngography on the Macquarie University
Electropalatography
Electropalatography (EPG) is a technique used to monitor contacts between the tongue and hard palate, particularly during articulation and speech.
The EPG palate has 62 silver electrodes embedded in it. When the tongue touches these electrodes the pattern is recorded by a computer. When contact occurs between the tongue surface and any of the electrodes, particularly between the lateral margins of the tongue and the borders of the hard palate,
electronic signals are sent to an external processing unit. EPG provides dynamic real-time visual feedback of the location and timing of tongue contacts with the hard palate.
This procedure can record details of tongue activity during speech. It can provide direct articulatory information that children can use in therapy to monitor and improve their articulation patterns. Visual feedback is very important in the success of treating deaf children.
Electropalatography has been studied in a variety of populations, including children with cleft palate, children with Down's Syndrome, children who are deaf, children with cochlear implants, children with cerebral palsy and adults with Parkinson's disease. Therapy has proved to be successful in tested populations. Longitudinal studies with large sample sizes are needed to determine the long-term success of therapy.

EPG at Queen Margaret University
UCLA Phonetics Lab Electropalotography

Electroglottography

EGG on the University Stuttgart

Electromagnetic Articulography (EMA)
Introduction
Electromagnetic articulography is a non-invasive, and biologically safe instrumentation system that records and displays articulatory movements. It is based on an inductive measuring principle. Hixon (1971) and Van der Giet (1977) developed early articulograph-systems to record articulatory movements by means of alternating electromagnetic fields. The crucial problem with these devices was the lack of any correcting mechanism for misalignment between the transmitter coils and receiver coils, which could lead to measurement errors. At present, there are three different commercially available systems that differ in technical details. The Carstens Electromagentic Articulograph AG100 (Schonle et al, 1987; Tuller et al, 1990). Since 1995 Carstens Medizinelektronik and the Phonetics department of the University of Munich under the direction of Prof. Hans G. Tillmann and with the support of NTT Japan, have been developing the new 5-dimensional Articulograph AG500, the Electromagnetic Midsagittal Articulometer EMMA (Perkell et al, 1992), and the Movetrack from Swedwn (Bran-derud, 1985), which has, in contrast to the others, no automatic tilt correction.
CARSTENS Medizinelektronik Company
UCLA Phonetics Lab Electromagnetic Articulography

Because change happens

2008年1月10日星期四

Phonetics Website III

2008年1月2日星期三

Phonetics Website II

標籤

網誌存檔

關於我自己