Praxis SLP Licensure Exam

What is the expected center of gravity for a sibilant fricative?

1. At the center of the spectrum

2. Off-center in the spectrum

3. Lower than its skewness

4. Higher than its skewness

The correct answer is: Higher than its skewness

For a sibilant fricative, the expected center of gravity is higher than its skewness. This is due to the characteristics of sibilant fricatives, which are produced with a high-frequency noise component. The center of gravity, a measure that represents the average frequency of the sound energy, tends to be located at a higher frequency because sibilants like /s/ and /ʃ/ involve prominent energy concentrated in the higher frequency regions of the auditory spectrum. The skewness of a sound spectrum indicates how frequencies are distributed, and for sibilants, this distribution is typically skewed towards the higher frequencies. Consequently, the center of gravity being higher than the skewness reflects the dominance of higher frequencies in the acoustic output of sibilant fricatives. Understanding this relationship is critical for speech-language pathology, as it helps in the assessment and treatment of speech sound disorders that involve these types of sounds.