infrasonicadj.
/ɪnfrəˈsɒnɪk/ 1. Of, pertaining to, or designating sound waves or vibrations having a frequency below the audible range (i.e. less than 15–30 Hz).
ΘΚΠ
the world > physical sensation > hearing and noise > inaudibility > [adjective] > subsonic
subsonic1920
subaudible1922
infrasonic1927
the world > matter > physics > science of sound > vibration > [adjective] > below range
subsonic1920
infrasonic1927
1927 E. G. Richardson Sound x. 236 The lower pitch limit is about 16 vibrations per second. Slow vibrations..remain unperceived as tones if their rate of pulsation falls below this limit... Such ‘infra-sonic’ waves have been extensively studied by Esclangon.
1945 Electronic Engin. 17 328/3 These will not run well..at infra-sonic frequencies.
1960 McGraw-Hill Encycl. Sci. & Technol. XII. 506/1 Many problems in vibration, oceanography, seismology, and the dynamic behavior of elastic materials are analyzed by treating the phenomenon being studied as sound waves of infrasonic frequency.
1965 Aerospace Med. 36 817/2 It has been estimated that the very large super boosters of the future..will produce their maximum noise energy in the infrasonic range (below 20 cps).
1965 T. N. Davis in W. N. Hess Space Sci. v. 227 Infrasonic waves with periods ranging from 10–110 seconds are observed at auroral and middle latitudes. These appear only on nights of moderate or strong auroral activity.
2. Designating speeds below that of sound; subsonic. rare.
ΘΚΠ
the world > movement > rate of motion > [adjective] > greater or less than speed of sound
supersonic1932
subsonic1936
infrasonic1942
ultrasonic1942
hypersonic1946
transonic1946
1942 Jrnl. Royal Aeronaut. Soc. 46 85 Equations of general application are derived, proving that both for infrasonic and for ultrasonic (supersonic) velocities, an extremum of the cross-section is possible.
This entry has not yet been fully updated (first published 1976; most recently modified version published online June 2021).
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adj.1927