Intonation and Phonation in Young Adults with Down Syndrome

This paper investigates various aspects of intonation and phonation in young adults with Down syndrome. The speech of nine speakers with Down syndrome was analyzed acoustically for different aspects of intonation and phonation. The results of these analyses were compared to similar speech samples of nine typical speakers of Standard British English. The controls were matched for age and gender. Different aspects of speakersʹ individual pitch framework were analyzed, ie, organic and linguistic pitch ranges, voice compass, and declination. Phonation was investigated acoustically as maximum phonation time, jitter, and shimmer. The results suggest that speakers with Down syndrome exhibit normal respiratory capacity, a reduced organic pitch range, and a somewhat reduced linguistic pitch range. In terms of the melodic variation in the intonation patterns, a higher mean speaking fundamental frequency was found with generally a less melodious rendering of the intonation contours and a shallower declination. The analysis of phonation indicated reduced jitter, while shimmer did not deviate significantly from the control group. Although the observed deviations in the Down syndrome speakers are suggestive of lack of laryngeal control at the physiological level, it cannot be excluded at this stage that they may also reflect personality characteristics or the use of different linguistic strategies in implementing intonation patterns.