Since its inception, beam forming has become one of the most popular techniques in the acoustics society. Today acoustics engineers use this measurement technique for sound pressure visualization, noise source identification at mid and high frequencies. With the plentiful possibilities, many acoustics professionals want to use this technique but it could be very costly and time consuming at times.
The beam forming method complements near field acoustic holography method and can be used for mid to high frequencies (1000-10kHz). Since there are many ways to arrange the microphone positions in a sensor array, we introduced some reasoning and estimation as how to design an array with minimal sensors. In addition, in a stationary operating condition, the array could be rotated to gain more resolution and accuracy.
In this paper, we described the regular fixed position array designs with circular 8, cross 8 and circular 9 sensor arrays. Then, we introduced the design concept of a semi-random configuration, where the sensor location is replaced with a bar with A or B positions. Position A could be on one end of the bar and position B on the other. The fixture bar makes it easy to use, because based on the generated random number; you could slide sensor to either A or B position on the fly. The results are comparable to multi-sensor array with more sensors, thus the cost of the system is reduced since no phase-matched microphones and no large amount of microphones are needed.