This research involves the design and implementation of a high spatial resolution acoustic radiation measurement system for the purpose of collecting data about the acoustic radiation in 3 dimensions from musical instruments while they are being played by musicians. It is also possible for the system to be used to capture 3 dimensional data about other sound sources.
Each musician may, when they perform upon their instrument, attempt to play consistently with the same dynamics and tone, the same timing and feeling, but will ultimately fail. This is not a failing in the musician themselves, but rather a function of the fact that musicians are, like all people, biological beings, and therefore cannot perform exactly the same movement with the consistency required for scientific data gathering when the purpose of the movement is to actuate another object (the instrument in this case). The problem has been attempted to be solved by taking the musician out of the measurement process, and by mechanically actuating the instrument in order to make repeatable and consistent measurements, but this rather defeats the purpose, as the instrument will not play (in performance) without the musician present.
The very presence of the musician will change the acoustic behaviour of the musical instrument as the musician will absorb some of the acoustic energy radiated from the instrument, especially at high frequencies, and to a lesser extent, the mid-range and lower frequencies within the audible spectrum. (This is related to the physical wavelength of the sound pressure wave – where it is smaller than the dimensions of the human body of the musician it will tend to be absorbed, but when longer it will tend to diffract around the body and will not be absorbed much, if at all).
So, it has been proposed to make the acoustic radiation measurement system compatible with an instrument actually being played. This will involve a grid of sensors which surround the musician, taking measurements of data at spatially averaged points, but with higher spatial resolution than in any of the previously surveyed literature. This will allow the interpolation of that data in order to predict the frequency-amplitude response and the phase of those frequency components in any given direction around the instrument (or other sound source) which has been measured.
In order to make high resolution measurements of the acoustic behaviour of musical instruments under performance conditions, a measurement system has been designed which consists of a number of interconnected parts. These include the sensors arranged in array on a 3 dimensional grid, signal conditioning circuits to bias the sensors, a set of analogue to digital convertors to send the signals to the data capture devices, and an array of hard disk data recorders to capture the data being generated by the sensors. When the data is captured, it can be then organised, processed, analysed and displayed in various ways
