ˈinfrəˌˌ noun
Etymology: infra- + sound (III)
: a wave phenomenon of the same physical nature as sound but with frequencies below the range of human hearing
ˈinfrəˌˌ noun
Etymology: infra- + sound (III)
: a wave phenomenon of the same physical nature as sound but with frequencies below the range of human hearing
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012