Spectral properties and quantitative evaluation of hypernasality in vowels

Area of Science:

• Speech-Language Pathology
• Acoustic Analysis
• Speech Science

Background:

• Hypernasality, a speech disorder affecting resonance, is often assessed perceptually.
• Objective acoustic measures can provide valuable complementary data for hypernasality evaluation.

Purpose of the Study:

• To present a novel acoustic technique for evaluating hypernasality.
• To investigate the relationship between acoustic measures and perceptual judgments of hypernasality.

Main Methods:

• A preliminary study assessed nasal resonance in 17 normal and 16 hypernasal subjects.
• One-third-octave power spectra were analyzed.
• Factor analysis and multiple regression were used to correlate acoustic data with perceptual ratings.

Main Results:

• Hypernasal speech showed increased power between the first and second formants and reduced power in the second and third formant regions.
• Consensus perception of hypernasality accounted for 71% of the variance in perceptual ratings.
• Acoustic power levels strongly correlated with perceived hypernasality.

Conclusions:

• The proposed acoustic technique effectively differentiates hypernasal speech.
• Acoustic analysis of power spectra offers a reliable method for assessing hypernasality.
• This approach can enhance objective evaluation of speech resonance disorders.