G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
G10K11/025—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators horns for impedance matching