A quantitative output-cost ratio in voice production

Area of Science:

• Acoustics
• Speech Science
• Biophysics

Background:

• Objective voice analysis is crucial for diagnosing voice disorders.
• Existing methods may lack precision in quantifying vocal fold function.
• The output-cost ratio (OCR) offers a novel metric for voice production efficiency.

Purpose of the Study:

• To introduce and validate a quantitative output-cost ratio (OCR) for objective voice production analysis.
• To explore the relationship between OCR, glottal width, and subglottal pressure.
• To discuss the clinical implications of OCR for voice disorder assessment.

Main Methods:

• Developed a quantitative output-cost ratio (OCR) defined as acoustic output intensity divided by vocal fold collision intensity.
• Conducted laboratory experiments using 5 excised larynges at a constant fundamental frequency (150 Hz).
• Varied subglottal pressure (1.0–1.6 kPa) and glottal width (pressed to 2-mm gap), measuring OCR.

Main Results:

• Excised larynx experiments, without a vocal tract, showed a broad OCR maxima around 0.6 mm glottal width across tested pressures.
• OCR measurements were demonstrated using a specialized transducer suitable for human subjects.
• Computer simulations suggested sharper OCR maxima when vocal tract influence is included.

Conclusions:

• The quantitative output-cost ratio (OCR) provides an objective measure for voice production.
• OCR shows potential for clinical application in diagnosing and managing voice disorders, including hyper- and hypoadduction.
• Further research incorporating vocal tract dynamics could refine OCR's diagnostic accuracy.