Persons with neuro-physiological disorders or differences have to devote special attention and muscle effort to be understood, compared with talkers without such conditions. Some physical systems are likely to interfere with pronunciation or articulation and speech volume in several ways. Sharing this obstacle to understandable speech are those with multiple sclerosis, cerebral palsy, cleft palate, Parkinson disease, stroke, and other neuro-muscular diseases, as well as persons with significant hearing loss.
For these people, research has found differences in muscle tension or stiffness, differences in muscle movement, including less force and speed for speech muscles such as the tongue, lips and jaw. There also may be differences in speech volume and speech sounds due to differences in vocal fold movement (which makes the voice) and in lung muscle activity (which produces the breath needed to produce voice).
Several things must occur for a person’s speech to be understood. One of the most important is the audibility or loudness of the speech sounds. Another is the length or duration of the speech sounds. A third is for the sounds to be recognized as words.
In order to be understood, a talker has to make all three things happen, judge when each one occurs and know the amount of speech volume and type of enunciation or speech muscle tension needed to accomplish this. The result is intelligible speech.
The amount of speech volume and manner of enunciation required to produce intelligible speech depends both on the setting and on the talker’s physical system (neurological system, or brain and nerves, and speech muscle system).
Furthermore, a talker in a noisy place (such as a classroom or a car) has to devote special attention to speech volume and enunciation to be understood, compared to a talker in a quiet place. This is because speech sounds must be louder to be understood over the background noise.
A question for those individuals who have a speech disorder due to a medical condition is often “How understandable are they to listeners?” A second question is: “How can they best improve speech intelligibility so that people understand them?”
The assessment developed by Dr. Antonia Lawrence Johnson provides many answers about the understandability or intelligibility of speech.
The basis for Clear Talk Training Methods for Persons with Neuro-physiological Disorders or Differences
Dr. Antonia Lawrence Johnson’s study for her Ph.D. focused on intelligibility of speech. Research conducted in the last 50 years as well as investigations by Dr. Antonia Lawrence Johnson since 1996 have shown the importance of precise enunciation and speech volume instruction for persons with neuro-physiological disorders and differences.
Specifically, controlled clinical assessment has been done with persons with multiple sclerosis, cerebral palsy, cleft palate, Fredreich’s Ataxia, Progressive Supranuclear Palsy, moderate to advanced Parkinson’s disease (PD), PD and stuttering, PD and nonnative-born, closed head injury, cerebral vascular accidents (stroke), and vocal fold paralysis with stroke, cerebellar tumor, Reyes Syndrome, and persons with hearing loss. When trained explicitly to change their speech volume and enunciation using Clear Talk Therapeutic ™ strategies, these speakers with neuro-physiological disorders or differences increased their intelligibility significantly.