Performance of Nonlinear Energy Difference Ratio and Voice Type Component Profile Across Phoneme, Relative Sound...

Area of Science:

• Speech science
• Acoustic analysis
• Voice disorders

Background:

• Nonlinear energy difference ratio (NEDR) and voice type component profile (VTCP) are established acoustic metrics for voice classification.
• Their reliability across varying vocal intensities, speech sounds, and recording environments requires thorough investigation for clinical application.

Purpose of the Study:

• To evaluate the effectiveness of NEDR and VTCP under real-world variability.
• To determine the clinical diagnostic potential of these acoustic measures.

Main Methods:

• Thirty-one adults produced sustained vowels and fricatives at five sound pressure levels.
• Acoustic samples were analyzed to compute NEDR and VTCP values.
• Repeated-measures ANOVA tested the effects of intensity, sound type, and environment.

Main Results:

• NEDR demonstrated stability across vowels and voiced fricatives, with minor deviations at very soft phonation and with the voiceless fricative /s/.
• VTCP showed higher sensitivity to low intensities and noisy environments, leading to misclassification of healthy voices.
• NEDR proved more robust than VTCP across different recording environments.

Conclusions:

• NEDR exhibits stability across vocal intensity, phoneme type, and recording environments, indicating potential clinical utility, including telepractice.
• Further validation is needed for NEDR, particularly concerning its performance at very low intensities and with voiceless fricatives in disordered populations.