Resonance
OR RESONANCY, in acoustics, (1) Sound reflected by a surface less than 112.5 feet from the spot whence it originally traveled. The direct and the reflected sounds are confounded, but the one strengthens the other. Bare walls tend to be resonant; a walls hung with tapestry are not so. (2) The increase of sound produced by a sounding board, or by the body of a musical instrument. In medicine, more or less shrill sound heard by auscultation in the larynx or lungs of a person speaking, or of one affected with chest disease.
RESONATOR. an instrument invented by Professor Helmholtz for facilitating the analysis of compound sounds. It consists, in its simplest form, of a tapering tube or a hollow bulb, spherical or nearly so in form, having an opening at one side for the air, and a tube adapted to the ear at the other. When the instrument is fitted to one ear, the other being stopped, tones above or below the pitch of the resonator will be but imperfectly heard; but if a note be sounded correspondingly to its pitch the note will be intensified.