Methods for the assessment of low frequency noise
The following sounds were used in recent laboratory tests sponsored by DEFRA to determine how people react to low frequency sound. Tracks 1-5 were sampled from recordings taken over five days in a house where the residents complain of low frequency noise. ‘Beating 40Hz tone’ was synthesised to give a low frequency tone modulated at 1.5Hz, i.e. a low hum which ‘beats’ at 90 beats per minute. ‘Steady 40Hz tone’ is a tone without the modulation for comparison.
The sounds are predominantly at 40Hz (40 cycles per second), so if you play them on ordinary equipment you may hear nothing! You will need a system capable of reproducing low frequency sound, such as a subwoofer.