Design, manufacturing and validation of low cost, miniature acoustic chamber

摘要

One of the most important aspects of project management is the cost. Cost carries equal importance along with assured acoustic performance in case of anechoic chamber. This study focuses on the design of an acoustic test chamber based on the size of the sound source. Also, it gives emphasis on the use of recyclable plant based fibers in acoustic treatment of chambers. The acoustic test chamber presented in this paper meets the requirements for noise reduction according to ISO 3745, assures optimal acoustical conditions with cost effectiveness. A new measurement methodology i.e. S/N has been implemented to curtail dependence on reverberation chamber for noise reduction measurements. The lowest S/N observed is 20 dB at 50 Hz and found to be increasing with frequency in case of reference loudspeaker operated for pure tones. Conformity of the results for noise reduction has been assured by Shruti Box selected to play Nishad in Madhyam Saptsur. 36.4 dB S/N for random noise signal has been reported. Free - field characterization of acoustic test chamber has been implemented using two different methods. 1 Watt, 1 kHz, 1 m method shows spatial deviation of 0.805 dB from mean surface SPL. Another such method is Inverse square law using fixed reference position method. Deviations observed in the experiment are comparable to those seen in the literature. From results it is observed that multilayer absorption treatment is most effective from the viewpoint of noise reduction, optimum free - field conditions and cost minimization. The total cost of acoustic test chamber is INR73000/-. We believe that the information presented in this paper will be useful to industries and research institutes for manufacturing of acoustic chamber in low cost for affordable noise studies.