A voice accumulation--validation and application.

Studies of vocal behavior under natural conditions require suitable techniques for obtaining records of voice use. We describe the operation of a newly designed voice accumulator that allows registration of fundamental frequency and phonation time during a 12-hour period. The device is based on microprocessors and allows accumulation of the voice fundamental frequency within 60-600 Hz. The voice signal is picked up by a contact microphone attached to the front part of the neck. Analysis of fundamental frequency distribution and phonation time is made on a personal computer. Validation of the device shows it to provide accurate measurements of fundamental frequency, although it tends to underestimate phonation time. In a field test, the accumulator was used to analyze vocal behavior during two work-days in a group of nurses and a group of speech pathologists. Overall, the speech pathologists had a lower fundamental frequency level and higher values of phonation time than the nurses. These field results confirm the validation of the voice accumulator.