Speech production in hearing-impaired children.

Investigations in recent years have indicated that only about 20% of the speech output of the deaf is understood by the "person-on-the-street." This lack of intelligibility has been associated with some frequently occurring segmental and suprasegmental errors. Errors of voicing and omission of consonants as well as vowel substitutions are common articulatory problems. Suprasegmental errors are associated with problems of timing, intonation, and voice quality. Yet, in spite of the relatively consistent findings regarding these frequently occurring errors, the correlation between the errors and overall speech intelligibility is less clear. The interrelationship between error types and the frequency of occurrence of a particular error type must be taken into consideration when interpreting the true effect of the error type on speech intelligibility. It is only when this is determined that one can begin to predict how much improvement to expect from correction of specific errors.