microphonous

mi`croph´o`nous

    (mî`krǒf´ô`nŭs or mĭ`krǒf´ô`nŭs)
a.1.Serving to augment the intensity of weak sounds; microcoustic.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.