A voice accumulator device: evaluation based on studio and field recordings.

A voice accumulator is a portable device for long-term measurements of voice use in natural conditions. A contact microphone attached to the front part of the neck registers vocal fold vibrations. The purposes of the present study were: 1) to evaluate the voice accumulator's two measuring programs optimized for registration of fundamental frequency (F0) and phonation time, respectively; and 2) to test the voice accumulator for field recordings. Four healthy subjects were recorded in a sound-proof booth simultaneously with one contact microphone into a voice accumulator and one contact microphone into a computer. In terms of F0 and phonation time, the results showed that correlations between the voice accumulator's two measuring programs and a signal-processing program were high (r > or = 0.85) for all subjects but one. The inter-subject variability was large. A prerequisite for reliable vocal fold vibration detection by the voice accumulator was a careful placement and a firm attachment of the contact microphone on the neck. Four subjects were recorded with the voice accumulator during a working day. It was concluded that the voice accumulator is an overall good instrument for measurements of F0 and phonation time, and thus is useful for both clinical work and research.