The sound radiation and directivity of glockenspiel bars

The directivity of a musical instrument describes the predominant directions that sound radiates from that instrument when it is being played. The shape of an instrument, as well as the note and playing style, can greatly affect its sound radiation and directivity. The glockenspiel is a percussion instrument made of pitched metal bars of uniform thickness laid out in a keyboard pattern and set on a frame. It produces sound when the player strikes the bars with a mallet. Uniform beam theory is often used to describe the modal behavior of the individual glockenspiel bars. However, when a single bar is stuck, the other surrounding bars and support frame influence the sound radiation and directivity. Therefore, glockenspiel measurements were performed using a directivity measurement system which has previously been used to measure musical instrument directivity. To eliminate strike-to-strike variance, an automatic striking device was used. This work will compare the sound radiation and directivity of a glockenspiel bar in the standard configuration, to an individual glockenspiel bar outside of the frame.