THE EFFECT OF CHANGES IN HEARING STATUS ON SPEECH SOUND LEVEL AND SPEECH BREATHING - A STUDY CONDUCTED WITH COCHLEAR IMPLANT USERS AND NF-2PATIENTS

According to a dual-process theory of the role of hearing in speech pr oduction, hearing helps maintain an internal model used by the speech control mechanism to achieve phonemic goals. It also monitors the acou stic environment and guides relatively rapid adjustments in postural p arameters, such as those underlying average speech sound level and rat e, in order to achieve suprasegmental goals that are a compromise betw een intelligibility and economy of effort. In order to obtain evidence bearing on this theory, acoustic and aerodynamic measures were collec ted from seven adventitiously deaf speakers who received cochlear impl ants, three speakers who had severe reduction in hearing following sur gery for Neurofibromatosis-2, and one hard of hearing speaker. These s peakers made recordings of the Rainbow Passage and an English vowel in ventory before and after intervention. All but one of the postlinguall y deaf speakers who received prosthetic hearing reduced speech sound l evel, SPL. Three of these significantly increased a measure of inferre d glottal aperture, H1-H2, and their session means for these two param eters were inversely correlated longitudinally. All but one of the spe akers terminated respiratory limbs closer to functional residual capac ity (FRC) once prosthetic hearing was supplied, Finally, the implant u sers' average values of air expenditure moved toward normative values with prosthetic hearing. These results are attributed to the mediation of changes in respiratory and glottal posture aimed at reducing speec h sound level and economizing effort. (C) 1998 Acoustical Society of A merica. [S0001-4966(98)04211-8].