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| low-frequency noises | |||
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| infrasonic sounds | |||
| infrasound Vibrations of the air at frequencies too low to be perceived as sound by the human ear, below about 15 hertz; infrasonic vibration | |||
| infrasound | |||
| infrasonic; infrasonic frequency | |||
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infrasons : 3 phrases in 3 subjects |
| Communications | 1 |
| Information technology | 1 |
| United Nations | 1 |