ASA 124th Meeting New Orleans 1992 October

3pNS6. Elimination of the influence of wearer's voice by a two-dosimeter system.

P. E. Giua

C. D. Messino

C. N. R., Via Cassia 1216, 00189 Rome, Italy

D. L. Johnson

EG&G Special Projects, Albuquerque, NM

Results are reported on a two-dosimeter system for the measurement of the daily personal exposure to noise. This system is supposed to estimate the true noise dose without the influence of the voice of the wearer. Two identical dosimeters were used with their microphones located on a helmet, in the front and back positions, respectively. The dosimeters simultaneously measured the L[sub eq] and the n-percentile-exceeded levels. These data were then used to eliminate the voice contribution to the noise dose. Provided certain constraints are fulfilled, preliminary results obtained in various environmental conditions have shown good performance of this system, especially at low noise levels. Main constraints are: (1) the daily measurement should be divided in homogeneous periods with respect to noise, and (2) if the wearer speaks for a certain period fraction, his or her voice level should be consistent with the Lombard effect. Examples are given.