Input acoustic impedance measurement of Ney with Pulse reflectometry method

Investigation of frequency variations of acoustic impedance can play an important role in identification and optimization of a musical instrument. For a simple tube, the input acoustic impedance can be calculated by analytical methods; for complex geometry objects like wind instrument, however, it cannot be simply computed. Therefore, the impedance is measured for wind instruments. This paper is report of first experiment for measuring the input acoustic impedance of Ney (an Iranian woodwind instrument). For this purpose, a pulse reflectometer device was made. For assurance of correct operation of the reflectometer, in the first step, the input acoustic impedance of a three sections step tube was measured and the results were compared with calculated results using well known formula. the acoustic impedances of a Do-ney for various fingering in six case (from closed all holes to opened all holes) were measured. The results show that, contrary to what seen for flout, the frequencies of minima of the impedance curves have some discrepancies with the frequencies of corresponding playable notes. This may relate to the role of mouth of instrument player in producing tones of ney.