Frequency Content of Breath Pressure and Implications for Use in Control

The breath pressure signal applied to wind music instruments is generally considered to be a slowly varying function of time. In a context of music control, this assumption implies that a relatively low digital sample rate (100-200 Hz) is sufficient to capture and/or reproduce this signal. We tested this assumption by evaluating the frequency content in breath pressure, particularly during the use of extended performance techniques such as growling, humming, and flutter tonguing. Our results indicate frequency content in a breath pressure signal up to about 10 kHz, with especially significant energy within the first 1000 Hz. We further investigated the frequency response of several commercially available pressure sensors to assess their responsiveness to higher frequency breath signals. Though results were mixed, some devices were found capable of sensing frequencies up to at least 1.5 kHz. Finally, similar measurements were conducted with Yamaha WX11 and WX5 wind controllers and results suggest that their breath pressure outputs are sampled at about 320 Hz and 280 Hz, respectively.