Ultrasonic components of musical instruments

There are few works characterizing the ultrasonic components emitted by musical instruments, primarily because it did not seem worthwhile to measure an energy that was difficult to register and that it is not perceived by humans. Registering sounds over 20 kHz is possible today with typical audio equipment. There exists low cost equipment such as microphones, sound cards and speakers that work with frequencies extending the traditional HiFi standard. The possibility of perceiving frequency components over the audible range is still a matter of debate, but we think that it is important to know how much energy there is in musical instruments in the ultrasonic range in order to fuel that debate. In a previous work, our research group performed energy measurements over the standard audible range for some musical instruments. This paper reports new findings about the ratio of high to low frequency energy over time for several musical instruments and different angles.