Phonetics. amplification of the range of audibility of any source of speech sounds, especially of phonation, by various couplings of the cavities of the mouth, nose, sinuses, larynx, pharynx, and upper thorax, and, to some extent, by the skeletal structure of the head and upper chest. the distribution of amplitudes among interrelated cavities in the head, chest, and throat that are characteristic for a particular speech sound and relatively independent of variations in pitch.
Physics. the state of a system in which an abnormally large vibration is produced in response to an external stimulus, occurring when the frequency of the stimulus is the same, or nearly the same, as the natural vibration frequency of the system. the vibration produced in such a state. a hadron with a very short lifetime, of the order of 10 −23 sec.