Closing and Opening Phase Variability in Unilateral Paresis

Adrian Fourcin and Martin Ptok

Four examples of the use of vocal fold contact phase measurement are discussed for unilateral paresis. In each case this aspect of voice quality is of greater importance than the physical measurement of loudness and pitch related parameters. For three of the cases electro-stimulation has been used as a main part of the treatment. Phonation in both connected speech and, for comparison, in sustained sound production has been used with electro-laryngograph / egg signals providing the basis for measurement. The main new descriptors that have been found to be useful relate to: vocal fold closure and closure duration regularities and distributions; but reference is also made to related measures of peak acoustic amplitude. The new measures described give, in some cases, quite striking results that are of auditory significance and potentially of clinical value.

Measuring voice in the clinic - Laryngograph® Speech Studio analyses
Adrian Fourcin, Julian McGlashan and Richard Blowes
(Presented at the 6th Voice Symposium of Australia. Adelaide, Oct. 2002)

The aim is to get down to simple basics - and to provide a straightforward set of clinically useable quantitative acoustic analyses that reflect important aspects of what is so obvious to the ear of the listener.

Loudness, pitch and quality are widely used to describe essential aspects of a speaker’s voice. However, their basic links with simple parameters of auditory processing are currently little used either in analysis or therapy. In the present work the application of pitch perceptual criteria is described in the provision of an integrated framework for practical clinical assessment and therapy. Sustained sounds are shown to require quite different levels of sampling accuracy from those needed for ordinary connected speech. Radically useful results come from the application of these basic ideas to the representation and analysis of the pathological and the normal voice in case management and audit. Even very abnormal speech samples can be seen to have measurable structures of pitch, loudness and quality - in the midst of apparent disorder.

Examples are discussed of the application of these approaches to pathological voice samples from clinics in several countries. Results from five main analysis types are examined:-

- sustained vowel measurement using standard techniques but with 1MHz period time sampling
- vocal fold frequency distributions based on voice frequency difference limen related bin sizes and both first and second order (digram) analyses to show the effect of pitch perturbation
- crossplots of vocal fold period to period variability which give an overview of intrinsic structure and provide a base for the measurement of irregularity which takes account of normal intonational variation in the speaker’s voice
- phonetogram and amplitude distribution analyses of connected speech using both simple and digram plots for ordinary connected speech
- closed phase ratio distributions again using first and second order analyses to provide measures of this aspect of voice quality.

Two signal inputs have been used, from an acoustic microphone and an electrolaryngograph. These inputs are also basic to a related development in stroboscopy. Although sustained sounds depend on different mechanisms of auditory monitoring and productive control, data from connected speech analysis can be of vital help in guiding the design and clinical use of new stroboscopic equipment.

Aspects of Voice Quality
Eva Carlson and David Miller
(International Journal of Language and Communication Disorders, Vol.33 Suppl. 1998)

One approach to outcome measures for speech and language therapy is to display measures of the physical, acoustic, correlates of the perceptually salient features of the structure of speech. A difficulty with this approach is that there is no simple mapping of physical correlates onto speech percepts. In this workshop the physical measures of voice fundamental frequency and larynx contact quotient are explored in relation to the perception, analysis and treatment of aspects of voice quality in a speech and language therapy clinic. A fundamental principle is to analyse samples of continuous speech. The workshop will focus on clients with unilateral vocal fold paralysis.

Interactive Therapy Displays
Evelyn Abberton, Xinghui Hu and Adrian Fourcin
(International Journal of Language and Communication Disorders, Vol.33 Suppl. 1998)

New developments are presented and discussed for the interactive display and separate measurement of frication and nasality in addition to voice quality. Different clinical problems require appropriate combinations of speech pattern elements support different approaches and these are supported by appropriate combinations of speech pattern elements. Particular use has been made of the Laryngograph® signal so that the displays can be given a sense of immediacy and are highly accurate.

Non-invasive monitoring of reflexive swallowing
Helen Firmin, Sheena Reilly and Adrian Fourcin

Two standard techniques are used for the clinical examination of abnormal swallowing: Videofluoroscopy which depends on irradiation, and Cervical Auscultation, which makes use of a stethoscope. Both of these techniques have important disadvantages. The first does not lend itself to routine use and the second provides no reliable quantitative information. The aim of this work was to investigate the utility of some of the methods used in Speech and Hearing Sciences. These methods do not use radiation and have the potential to give more accurate timing information than can be derived from auditory/acoustic monitoring. Pilot data were obtained from the simultaneous use of four sensors: an ear-plug microphone of the type used successfully for the detection of otoacoustic emissions; a standard miniature electret microphone ordinarily used for speech recording; a miniature accelerometer of the type sometimes used for monitoring nasality; and a standard electrolaryngograph. Swallow measurements were made with twenty normal adult subjects. The most effective single signal was that provided by the use of standard electrolaryngograph hardware and software. A small but significant increase in reliability came from the combined appraisal of two signals, from the Laryngograph® and an accelerometer.

Speechreading of words and sentences by normally hearing and hearing impaired Chinese subjects: the enhancement effects of compound speech patterns
Xinghui Hu, Adrian Fourcin, Andrew Faulkner and Jianing Wei

Speech perception requires a receiver to make decisions both about trends and also about the language patterns of a speaker. Hearing people use the speaker's speech signal as the direct sensory evidence. In the special case of visual speech perception, otherwise known as speechreading, this sensory evidence is derived from the visible articulation movements of speech. Unfortunately, many important articulation movements are invisible. On the segmental level, some articulation positions are difficult or impossible to distinguish. Even for those sounds that are visible, few have unique visual cues. At the suprasegmental level, the basic speech elements intonation and lexical tone which are mainly conveyed by the vibrating frequencies of the larynx, are totally missing in visible facial gestures. Therefore, a successful speechreader has to compensate for the resulting shortage of sensory data by taking maximal advantage of prior knowledge of language structure and of the linguistic and situational context. This process is demanding, however, and even the most competent speechreaders have to accept a substantial probability of error.

Pattern element hearing aids and speech assessment and training
Adrian Fourcin and Evelyn Abberton

This paper has been prepared for a meeting (in Beijing 9-10 IX 1996) organised jointly by the Chinese Academy of Sciences and the Department of Phonetics and Linguistics at UCL. The meeting is concerned with new technology hearing aids, with special reference to phonetically important speech dimensions and bio-active implants. The particular aim here is to give examples of speech element processing with special reference to perceptual and productive assessment. The same basic principles apply to assessment and training for both prosthesis and patient, however, and they can be briefly defined by the following summary points concerning the present and potential advantages of using essential speech dimensions:-

- clarity of perception and relevance to communication
- targeted signal processing
- complementary assessment of prosthesis and patient
- simply structured adult rehabilitation and training
- matching acquisition to normal stages of development Background

Precision Stroboscopy, Voice Quality and Electrolaryngography
Adrian Fourcin

The aim of this brief overview is to introduce the use of Laryngograph®, and EGG, voice measurement equipment and to give some examples of the newer methods of voice quality assessment that these techniques are beginning to make available. Special reference is made to the use of these methods in: precision stroboscopy; the analysis of connected speech; and in regard to their auditory relevance.