Effects of Altered Fundamental Frequency on Nasalance during Vowel Production by Adult Speakers at Targeted Sound Pressure Levels

Abstract

This study investigated the effects of altered fundamental frequency (F0) on nasalance levels of the vowels /i/ and /a/ produced by adults without cleft palate within a controlled sound pressure level (SPL) range. A prospective group design with convenience sampling from the University of North Carolina at Chapel Hill was used. 20 men and 20 women participated, aged 18 to 55 years. All were native English speakers with normal speech and language skills and adequate velopharyngeal function. The outcome measures were percentage nasalance obtained from the Nasometer 6200 (KayPentax) headset and the Computerized Speech Lab Model 4400 (CSL, KayPentax) during vowel production while speakers (1) targeted an SPL range of 75 to 85 dB and (2) targeted the SPL plus F0 range of 165 to 175 Hz. A significant univariate effect was found for the vowels /i/ and /a/ in the targeted SPL condition such that /i/ was produced with higher nasalance than /a/. A significant univariate effect was also found during production of /a/ in the targeted SPL plus F0 condition such that men produced /a/ with higher nasalance than women did. SPL appears to largely account for percentage nasalance differences between the vowels /i/ and /a/ produced by adult male and female speakers. Increased F0 by male speakers appears to influence percentage nasalance during production of the vowel /a/. Clinical implications in regard to assessment of hypernasality are discussed.