Introduction to
Instrumental Phonetics
The field of phonetics can be divided up into a
number of sub-fields¡Band 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¡Bas transmitted between mouth and ear) or
articulatory (the study of the way speech sounds
are made (¡yarticulated¡z) by vocal organs).
Instrumental phonetics is a quantitative
approach - it attempts to characterise speech in
terms of measurements and numbers¡Brather 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¡Bin 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¡Bincluding radiography (X-rays) for examining
activity inside the vocal tract¡Blaryngography
for inspecting the inside of the
larynx¡Bpalatography for recording patterns of
contact between tongue and palate¡Bglottography
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¡Bbut 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¡Bbut 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¡Bor spectrogram¡Bof an utterance¡Bin which
time is displayed horizontally¡Bfrequently
vertically¡Band intensity by the relative
blackness of the marks¡Bon a sheet of sensitized
paper. Since the development of acoustic
analyses in the late 1940s¡Bthe 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¡Bspectrographic information can be
generated electronically and displayed on a
screen.
X-ray technique
>Electromyography
An introduction to electromyography
Electromyography (EMG) was developed by
neurophysiologists¡Bsuch as Adrian and Bronk
(1929) and smith (1934). But it was at the end
of World War II¡Bwhen there was a marked
improvement in the technology and electronic
apparatus¡Bthat EMG began to be used by
anatomists¡Bkinesiologists¡Band clinicians.
EMG is a technique suited to the analysis of
skilled movements in general¡Band of speech
movements in particular. It gives the
opportunity to study the dynamics of speech
production¡Bnot only by describing which muscles
are contracting and when¡Bbut 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¡Band little attention has been paid to
the means by which these are affected. By the
1950s¡BEMG investigations of speech activity were
becoming more common: laryngeal muscles were
studied by Faaborg-Anderson (1957)¡Band by
Sawashima¡BSato¡BFunasaka and Totsuka (1958);
respiratory muscles were investigated by Stetson
(1951)¡Band by Draper¡BLadeforged and Whitteridge
(1959). During the 1960s¡BEMG was used to study
various speech organs¡Bsuch as the lips (McNeilage
1963; Fromkin¡B1966; Lvsaught et al,1961;
Ohman¡B1967; Ohman et al¡B1965)¡Bthe soft palate (Fritzell
1963; 1969; Lubker¡B1968)¡Bthe tongue (MacNeilage
and Sholes¡B1964; Smith and Hirano¡B1968)¡Band the
larynx (Faaborg-Anderson¡B1964; Faaborg-Anderson
and Vennard¡B1964; Hirano et al¡B1967). This
pioneering electromyographic research into
speech production involved single speech organs
only. Then¡Bseveral speech organs were studied at
the same time (Sussman et al¡B1973).
Gay¡BUshijima¡BHirose and Cooper (1974) recorded
EMG from muscles that control the movements of
the lips¡Btongue 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¡BHarris
and Kelso (1982) and Tuller¡BKelso and Harris
(1982) observed the transformation of
articulation¡Bstress and rate using EMG and
acoustic data: one lip muscle¡Bone 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¡Bone jaw muscle and two tongue
muscles. More recently¡Bmuch attention has been
directed towards the interaction among speech
muscles¡Bbecause one muscle contracts in the
context of many other opposing or augmenting
forces (Folkins¡B1981; Gentil and Gay¡B1986;
Gentil et al¡B1983; Hirose¡B1977; Honda et
al¡B1982; Tuller et al¡B1981). Speech motor
plasticity in the production of a particular
spoken utterance¡Bthat is variations among a
great number of muscles between several
subjects¡Bwere also evaluated (Gentil¡B1992).
EMG on the University of Oklahoma
EMG on University Stuttgart
Electrolaryngography
The eletectrolaryngograph (or simply ¡ylaryngograph¡z)
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¡Band also as the basis of PC-based
interactive voice therapy. Electrodes are
attached to the neck on each side of the thyroid
cartilage¡Band 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¡Band 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¡Banalysis and therapy
Electrolaryngography on the Macquarie University
electroglottography(EGG)
Electropalatography
Palatography
Electropalatography (EPG) is a technique
used to monitor contacts between the tongue and
hard palate¡Bparticularly 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¡Bparticularly between the
lateral margins of the tongue and the borders of
the hard palate¡B
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¡Bincluding children with
cleft palate¡Bchildren with
Down's Syndrome¡Bchildren who are
deaf¡Bchildren with
cochlear implants¡Bchildren 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
Electromagnetic
Articulography (EMA)
Introduction
Electromagnetic articulography is a non-invasive¡Band
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¡Bwhich could
lead to measurement errors. At present¡Bthere are
three different commercially available systems
that differ in technical details. The Carstens
Electromagentic Articulograph AG100 (Schonle et
al¡B1987; Tuller et al¡B1990). 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¡Bhave been developing the new
5-dimensional Articulograph AG500¡Bthe
Electromagnetic Midsagittal Articulometer EMMA (Perkell
et al¡B1992)¡Band the Movetrack from Swedwn
(Bran-derud¡B1985)¡Bwhich has¡Bin contrast to the
others¡Bno automatic tilt correction.
CARSTENS Medizinelektronik Company
UCLA Phonetics Lab Electromagnetic
Articulography
Introduction to
Instrumental Phonetics
Spectrography
X-ray technique
>Electromyography
Electrolaryngography
electroglottography(EGG)
Electropalatography
Palatography
Electromagnetic Articulography (EMA)
Spectrography
X-ray technique
>Electromyography
Electrolaryngography
electroglottography(EGG)
Electropalatography
Palatography
Electromagnetic Articulography (EMA)