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Infrasound arrays at monitoring station in Qaanaaq, Greenland.. Infrasound, sometimes referred to as low frequency sound or subsonic, describes sound waves with a frequency below the lower limit of human audibility (generally 20 Hz, as defined by the ANSI/ASA S1.1-2013 standard). [1]
Recordings and playback experiments support that elephants use the infrasonic components of their calls for communication. Infrasonic vocalizations have been recorded from captive elephants in many different situations. The structure of the calls varies greatly but most of them range in frequency from 14 to 24 Hz, with durations of 10–15 seconds.
The hearing range of birds is most sensitive between 1 kHz and 4 kHz, but their full range is roughly similar to human hearing, with higher or lower limits depending on the bird species. No kind of bird has been observed to react to ultrasonic sounds, but certain kinds of birds can hear infrasonic sounds. [29] "Birds are especially sensitive to ...
The subsonic speed range is that range of speeds within which, all of the airflow over an aircraft is less than Mach 1. The critical Mach number (Mcrit) is lowest free stream Mach number at which airflow over any part of the aircraft first reaches Mach 1. So the subsonic speed range includes all speeds that are less than Mcrit. Transonic: 0.8–1.2
The filter section may also include a high-pass "infrasonic" or "subsonic" filter, which prevents the subwoofer driver from attempting to reproduce frequencies below its safe capabilities. Setting an infrasonic filter is important on bass reflex subwoofer cabinets, as the bass reflex design tends to create the risk of cone overexcursion at ...
Their critical Mach numbers are higher than those of subsonic and transonic aircraft, but are still less than Mach 1.0. The actual critical Mach number varies from wing to wing. In general, a thicker wing will have a lower critical Mach number, because a thicker wing deflects the airflow passing around it more than a thinner wing does, and thus ...
The brown note (sometimes brown tone or frequency), 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" using sound waves ...
Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. [1] The exact range of speeds depends on the object's critical Mach number, but transonic flow is seen at flight speeds close to the speed of sound (343 m/s at sea level), typically between Mach 0.8 and 1.2.