Validity of the Nasometer Measuring the Temporal Characteristics of Nasalization

Abstract

Objective: To examine the validity of the Nasometer (KayPENTAX, Lincoln Park, NJ) in measuring the temporal characteristics of nasalization by comparing the Nasometer measures to the measures from an external criterion procedure. Design: Speech samples consisted of three rate-controlled nonsense syllables, which varied in their vowel compositions: /izinizi/, /azanaza/, and /uzunuzu/. Acoustic data were recorded simultaneously through the Nasometer and an external criterion procedure (a specialized microphone set that collected acoustic signals separately for the nasal and oral channels). Speech segment durations measured from the two instrumental conditions were compared on the Nasometer display and the Computerized Speech Lab (KayPENTAX, Lincoln Park, NJ) display. Five durational variables were measured: total utterance duration, nasal onset interval, nasal consonant duration, nasal offset interval, and total nasalization duration. Participants: Fourteen normal adults who speak American English as their first language participated in the study. Results: No significant differences were found between the measures from the Nasometer and those from an external criterion procedure in all the durational variables pertinent to nasalization. Different vowels, however, yielded significantly different patterns in these durational variables, in which the low vowel /a/ context revealed significantly longer total nasalization duration than did the high vowel /i/ and /u/ contexts. Conclusions: The results suggest that the Nasometer can be used as a valid tool to measure the temporal characteristics underlying nasalization and confirm significant vowel effects on the temporal patterns of nasalization.