Assessment of nasalization in the speech of deaf children.

Nasality is widely recognized as a problem in the speech of many deaf people. This paper describes one approach to the assessment of nasalization and to the development of visual aids to assist in training of velopharyngeal control. The approach involves detection of the velopharyngeal opening during voiced sounds by means of a small accelerometer attached to the nose, and presentation of the accelerometer output on a computer-controlled visual display. The display may be used as a training aid, or for the purpose of analyzing either recorded or live speech. Objective data are presented on some of the properties of the accelerometer output for the speech of people with normal hearing and of a number of children whose hearing is severely impaired. These data show inadequate velopharyngeal control, particularly improper nasalization of certain vowels, for a significant number of the deaf children. For a group of the hearing-impaired children, subjective judgments of the adequacy of velopharyngeal control and of other speech attributes were obtained. Correlations among these judgments and relations between judgments of adequacy of velopharyngeal control and the objective measures of nasalization are shown. Some comments are made on the development of procedures for the training of velopharyngeal control using the display as an aid.