DADiSP helps the New York Medical College investigate and research human speech disorders

Historically, human speech disorders have often been attributed to psychological rather than physical causes. Until recently, technological limitations prevented thorough investigation of such pathologies as stuttering and spasmodic dysphonia. Dr. Rick Roark and colleagues at the New York Medical College are using a PC-based computer system to gain an understanding of the function of the human central nervous system in normal and pathologic speech production in order to sort out the psychological and physiological aspects of speech problems. The team has had to solve many tough technical problems in order to do so.

It is difficult to choose instrumentation for a laboratory in any health science field because such research is characterised by huge data sets, complex quantitative measures, and invasive physiologic data acquired from human subjects. Large data sets slow down analysis. Complex data extraction and analysis use a great deal of computer power, resulting in skyrocketing research costs. Data are difficult to reacquire if the first set isn’t sufficient. Measuring the body’s many movements in speech and analysing their interactions is difficult, but it is the best way to get an accurate assessment of a problem. By using ingenious measurement techniques on human volunteers and analysing the resulting gigabytes of data in custom PC computer programs, Dr. Roark and colleagues are creating a picture of a long-misunderstood ailment. Their research requires an acquisition, data management, display, and analysis system that can perform complex, multi-dimensional data extraction tasks even when data are acquired by diverse instruments at several different sampling rates. The team’s software must be flexible, user-friendly, and backed up by superior technical support.

Dr. Roark and colleagues use DADiSP as the core graphical display and analysis tool in their extensive data acquisition and analysis system. Their system’s architecture promises a wide application in many areas of health science. The Vocal Motor Control Laboratory (VMCL) has a capability rivalled only by two other laboratories in the world, both of which are mainframe-based.

A typical acquisition task involves attaching an array of sensors to human volunteers. These sensors record up to 16 time-synchronous physiologic measurements at a variety of sampling rates while the subject says a word or sentence. Most digital signal processing software does not permit concurrent differential sampling rates, but DADiSP does. In one session, acquired data might include eight electromyographic (EMG) signals (electrical muscle potential signals recorded by needle electrodes inserted into muscles) sampled at 5 kHz, two laryngeal kinematic signals acquired via instruments inserted through nasal or oral pathways and sampled at 20 kHz, two respiration signals sampled at 200 Hz, and a speech acoustic signal sampled at 10 kHz. Simultaneous video filming of the larynx is performed via endoscopy. Because few volunteers would want to repeat this experience, maximum integrity of the signal quality is vital.

Depending on the number of signals involved, a typical experimental session yields 100,000 bytes of digital data per second per subject. A research project might require 25 subjects (10 normal and 15 pathologic) to attend four two-hour experimental sessions. During a project, some 50 gigabytes of physiologic data are acquired and stored directly to magnetic disk. Long-term storage of data is facilitated by the use of optical media. The research team created their own data analysis program with DADiSP. It is a menu-driven, continuous linked command file organised as a relational database. Time-marking, measure extraction, and signal annotation are all automated; one system feature permits extraction of a time subset of one signal in a worksheet for viewing or editing while all other signals in the worksheet are windowed automatically according to user-selected cursors. Acquired measures are updated automatically and stored. Accumulated measures are transferred to spreadsheets for final statistical analysis and comparison.

Dr. Roark believes that there is tremendous potential for DADiSP in health science research because current health science problems require solutions that make use of sophisticated architectures and multidisciplinary cooperation. He states that the success of his research group has depended upon dedicated collaborative effort. The group consists of two electrical engineers, two medical doctors, two speech scientists, and two computer scientists. Since the team has demonstrated that sophisticated research and development tasks can be performed using computer workstations instead of large, expensive mainframe computers, the VMCL is receiving attention from research groups that have relatively small budgets for hardware and software.

DADiSP is supplied and supported in the UK and Ireland by Adept Scientific plc, Amor Way, Letchworth, Herts. SG6 1ZA; telephone +44 (0) 203 695 7810, fax +44 (0) 203 695 7819, email; or see Adept’s World Wide Web site Adept Scientific is one of the world’s leading suppliers of software and hardware products for research, scientific, engineering and technical applications on desktop computers.

With offices in the UK, USA, Germany and throughout the Nordic region, Adept Scientific is one of the world’s leading suppliers of software and hardware products for research, scientific, engineering and technical applications on desktop computers.

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