Analysis of the variations in frequency for a trumpet B-flat to use “mute”.
Claudia Macías, Itzalá Rabadán, Ilhuicamina Servín · The Journal of the Acoustical Society of America · 2010
The effect that is produced in the acoustical characteristics of a B-flat trumpet when an obstacle is located at the exit of the bell has been investigated. To know how these characteristics have been modified, a professional trumpet player played some tones with three different conditions in the bell: bell free of obstacles, bell with a Harmon mute, and bell with the musician’s hand. The measurements were made in an anechoic chamber. Data were registered through a sound level meter type II which was connected to a computer and data were saved in a computer program, then the results were analyzed. The sound radiation patterns reveal that the energy that is radiated by the trumpet diminishes in all directions. The spectra show that the amplitude as well as the frequency of the signals change for all the tones. That is to say, when there is an obstacle at the exit of the bell, the boundary condition is different, and with this, the impedance and the effective length of the trumpet are affected. As a result, the frequency of the modes of vibration, the standing wave pattern as well as the timbre are affected.