Experimental and calculated frequencies of the Southeast Asian naw
Eric A. Dieckman, James P. Cottingham · The Journal of the Acoustical Society of America · 2006
The naw, an Asian free-reed gourd pipe, is constructed of pipes open at both ends with a free reed in the side of each pipe near one end. The pipes of the naw are cylindrical over a significant portion of their length but have a slightly tapered bore near the reed end. The bottom end of the pipe can be covered with the player’s thumb to bend the pitch. Previous research on the khaen, a similar instrument with a cylindrical bore, found that the sounding frequencies of the khaen are well approximated using the simple equation for an open cylindrical pipe. This is not possible for the naw. A method of transmission matrices has been used to calculate the theoretical resonant frequencies of the naw pipes, both open and closed. The calculated values agree well with the resonant frequencies determined experimentally by measuring the input impedance of the pipe. When blown normally, the open pipe sounds near its calculated frequency, while the closed pipe sounds slightly lower than the open pipe frequency. By underblowing the reed, however, the closed pipe can be made to sound near its predicted resonant frequency. [Research supported by NSF REU Grant PHY-0354058.]