Characterization of audible low frequency noise indoor environment

The propagation and attenuation characteristics of sound wave can signify and affect speech intelligibility in an enclosed room.Moreover, the lower frequency components of sound wave is the major concern for sound wave at this frequency range are the hardest to attenuate. The purpose of this research is to quantify the propagation and attenuation characteristics of sound wave at audible low frequency range. The project was kicked off by fabricating a new wedges design for the existing anechoic chamber in Makmal Penyelidikan Akustik, Fakulti Kejuruteraan Elektrik, UTMSkudai, Johor. Once the anechoic room was completely refurbished, measurement of reverberation time (RT60), sound pressure level (SPL) and SPL attenuation per doubling of distance were conducted. The results RT60, SPL and SPL attenuation per doubling of distance were obtained for one-octave center frequency from 125Hz to 4 kHz. It is concluded that the attenuation of energy of sound waves, bymeans of RT60 results, follow the established normal equal loudness contour. However, the SPL in anechoic room is found to be peaking up beginning at frequency 64Hz until 4 kHz. From SPL attenuation per doubling of distance results, it is concluded that the new refurbished anechoic room is able to handle test frequency of sound waves from 64Hz and above.