Suitability of minidisc (MD) recordings for voice perturbation analysis.

A new digital recording format, Minidisc (MD), shows promise for high-quality voice recordings. It is available in a portable size and uses magneto-optical recording techniques on a miniature compact disc. The disc can be recorded an unlimited number of times with essentially the same playback life span: however, the digital recording technique uses a data compression algorithm that may interfere with acoustic voice perturbation analysis.

Conversion of a head-mounted microphone signal into calibrated SPL units.

A method is reviewed for conversion of a microphone signal into calibrated Sound Pressure Level (SPL) units. The method follows American National Standards Institute (ANSI) standard for S1.4 SPL meters and requires an accurate SPL meter and an accurate calibration sound source for conversion.

Miniature head-mounted microphone for voice perturbation analysis.

The miniature head-mounted microphone has become the microphone of choice in clinics, laboratories, and professional work settings where voice amplification or recording is needed and subject mobility is desirable. In this study, a miniature head-mounted condenser microphone was compared to a larger, professional grade stand-mounted condenser microphone for perturbation analysis. Amplitude and frequency perturbation measures of human phonation were made for comparison.

Effect of microphone type and placement on voice perturbation measurements.

This study was conducted to explore the effects of microphone type (dynamic vs. condenser) and pattern (omnidirectional vs. cardioid) on the extraction of voice perturbation measures for sustained phonation.

Rapid voice tremor, or "flutter," in amyotrophic lateral sclerosis.

In an attempt to clarify the origin and frequency characteristics of a rapid voice tremor, or "flutter," in patients with amyotrophic lateral sclerosis (ALS), eight patients (four men and four women; ages 42 to 70 years) who had ALS and rapid voice tremor and an age- and sex-matched control group of eight subjects were asked to sustain the vowel /a/ and their voices were recorded for later analysis. Each segment of phonation was demodulated into amplitude and frequency components. From each subject's 8-second amplitude and frequency signals, a fast Fourier transform analysis was done on a 1-second segment previously identified perceptually as having the most apparent tremor or flutter.