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In February 2016, a high-pitched noise was heard intermittently at night in Forest Grove, Oregon. The Department of Forestry determined that their equipment was not the cause of the sound. [1] The news about the noise was first shared with Dave Nemeyer by a Forest Grove resident, who posted a video of it on the city's Facebook page. [2]
Ululation (/ ˌ j uː lj ʊ ˈ l eɪ ʃ ən, ˌ ʌ l-/ ⓘ, [1] [2] from Latin ululo), trilling or lele, is a long, wavering, high-pitched vocal sound resembling a howl with a trilling quality. It is produced by emitting a high pitched loud voice accompanied with a rapid back and forth movement of the tongue and the uvula. [3]
The sound, always peaking between 30 and 40 Hz (hertz), was found to only be heard during cool weather with a light breeze, and often early in the morning. These noises were often confined to a 10-kilometre (6 mi) wide area. [3]
A cause is traumatic noise exposure that damages hair cells in the inner ear. [33] Some evidence suggests that long-term exposure to noise pollution from heavy traffic may increase the risk of developing tinnitus. [34] When there does not seem to be a connection with a disorder of the inner ear or auditory nerve, tinnitus can be called "non-otic".
Singing sand dunes, an example of the phenomenon of singing sand, produce a sound described as roaring, booming, squeaking, or the "Song of Dunes". This is a natural sound phenomenon of up to 105 decibels, lasting as long as several minutes, that occurs in about 35 desert locations around the world. The sound is similar to a loud low-pitch rumble.
The Mosquito or Mosquito alarm is a machine used to deter loitering by emitting sound at high frequency. In some versions, it is intentionally tuned to be heard primarily by younger people. Nicknamed "Mosquito" for the buzzing sound it plays, the device is marketed as a safety and security tool for preventing youths from congregating in ...
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Environmental noise regulations usually specify a maximum outdoor noise level of 60 to 65 dB(A), while occupational safety organizations recommend that the maximum exposure to noise is 40 hours per week at 85 to 90 dB(A). For every additional 3 dB(A), the maximum exposure time is reduced by a factor 2, e.g. 20 hours per week at 88 dB(A).