Sound-Power Production in Wind Instruments
Arend Bouhuys · The Journal of the Acoustical Society of America · 1965
This paper presents data for output sound power PO of wind instruments relation to input power PI supplied by the player. PI was calculated as pV̇, where p equals mouth pressure and V̇ air flow rate through the instrument. PO was calculated from sound-pressure level and measurements of reverberation time in a live room of known volume. A part of the data was obtained in a room of unknown characteristics; from 15 comparable measurements on 8 different instruments in both the live and the unknown room, data were obtained that allowed calculation of PO also from other experiments in the unknown room. Measurements were made on single notes, played both pp and ff, on each instrument; one low and one high note on the scale of each instrument were chosen. The ratio PO/PI, representing the mechanical efficiency of wind instruments as sources of sound power, varies from less than 0.001% to about 2%. It appears to increase with increasing PI and, in some instruments, with frequency. The consistent results obtained for 3 different flutes played by one performer suggest that the variability noted in the other data at least partially reflects individual differences in mechanical efficiency.