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The report "A Review of Published Research on Low Frequency Noise and its Effects" [54] contains a long list of research about exposure to high-level infrasound among humans and animals. For instance, in 1972, Borredon exposed 42 young men to tones at 7.5 Hz at 130 dB for 50 minutes.
LFEs include both low-pitched musical notes and low-pitched sound effects. The musical soundtrack for many films includes bass instruments that produce very low notes. . Until the 1970s, most of the low-pitched instruments were natural, acoustic instruments, such as the double bass or the pipe organ's pedal key
Infrasound is sound at frequencies lower than the low frequency end of human hearing threshold at 20 Hz. It is known, however, that humans can perceive sounds below this frequency at very high pressure levels. [1]
Annoyance effects of noise are minimally affected by demographics, but fear of the noise source and sensitivity to noise both strongly affect the 'annoyance' of a noise. [42] Sound levels as low as 40 dB(A) can generate noise complaints [43] and the lower threshold for noise producing sleep disturbance is 45 dB(A) or lower. [44]
The brown note, also sometimes called the brown frequency or brown noise, is a hypothetical infrasonic frequency capable of causing fecal incontinence by creating acoustic resonance in the human bowel. Considered an urban myth, the name is a metonym for the common color of human faeces. Attempts to demonstrate the existence of a "brown note ...
Although sounds of such low frequency are too low for humans to hear as a pitch, these sound are heard as discrete pulses (like the 'popping' sound of an idling motorcycle). Whales, elephants and other animals can detect infrasound and use it to communicate. It can be used to detect volcanic eruptions and is used in some types of music. [35]
A very low rate can be used to modulate a filter's cutoff frequency, thereby providing the characteristic gradual sensation of the sound becoming clearer or closer to the listener. Alternatively, a high rate can be used for bizarre 'rippling' sound effects (indeed, another important use of LFO is for various sound effects used in films).
Seismic exploration involves the use of low frequency sound (< 100 Hz) to probe deep into the seabed. Despite the relatively poor resolution due to their long wavelength, low frequency sounds are preferred because high frequencies are heavily attenuated when they travel through the seabed. Sound sources used include airguns, vibroseis and ...