Application of Linear Discriminant Analysis to the Long-term Averaged Spectra of Simulated Disorders of Oral-Nasal Balance

Abstract

Objective Acoustic studies of oral-nasal balance disorders to date have focused on hypernasality. However, in patients with cleft palate, nasal obstruction may also be present, so that hypernasality and hyponasality co-occur. In this study, normal speakers simulated different disorders of oral-nasal balance. Linear discriminant analysis was used to create a tentative diagnostic formula based on the long-term averaged spectra (LTAS) of the speech stimuli. Materials and Methods Eleven female participants were recorded while reading nonnasal and nasal speech stimuli. LTASs of the recordings were run for their normal oral-nasal balance and their simulations of hyponasal, hypernasal, and mixed oral-nasal balance. The amplitude values (in decibels) were extracted in 100-Hz intervals over a range of 4 kHz. Results A repeated-measures analysis of variance of the normalized amplitudes revealed a resonance condition–frequency band amplitude interaction effect ( P < .001). A linear discriminant analysis of the participants’ LTAS led to formulas correctly classifying 80.7% of the oral-nasal balance conditions. Conclusion The simulations produced distinctive spectra enabling the creation of formulas that predicted the oral-nasal balance above chance level. Future research with speakers with oral-nasal balance disorders will be needed to investigate the potential of this approach for the clinical diagnosis of disorders of oral-nasal balance.