1 .) A compressor is placed at a height of 0,5m above an acoustically-hard ground next to a vertical acoustically hard outside wall. Its Sound Power level spectrum has a strong peak in the 250Hz octave band, in which the A-weighted level is 100 dB(A). A long 2m high thin barrier is placed 2m from the compressor to reduce the noise level at a 1.2m high receiver located at a horizontal distance of 15m from the compressor
(a) Estimate the A-weighted sound pressure level in the 250Hz band at the receiver.
(b) If the barrier must instead be placed 7.5m from the compressor, calculate the height this
2.) A 0.5 m2 sample of building material is placed in a window between a receiving room and source room_ there is no significant sound transmission except through the sample. Average sound levels in the 1 kHz °octave band are 97 dB in the source room and 72 dB in the receiving room. The equivalent absorption area of the receiving room is 1.5m2. Find transmission loss (TI.) and transmission coefficient for the sample at 1kHz.
(b) Using MS Excel find the sound transmission class of a wall based on the following measured transmission is values for the one third octave bands beginning at 125 Hz
27, 30, 34, 35, 40, 42, 41, 47, 49, 49, 52, 48, 41, 45,A8, 45.