(music) An opening in the belly of a stringed instrument that increases its volume and enhances its tone quality.

plural of sound box

A rod or piece of iron used to ascertain the depth of water in a ship's hold. It is let down in a groove by a pump. / A probe used in urethral sounding

plural of radio sounding

(phonology) A rule that describes historical sound change (the change in pronunciation of a given sound or cluster of sounds) in the development of a language.

(lutherie) A wooden rod located inside the body of a violin-family instrument, close to the treble-side bridge foot.

plural of sounding rocket

(space science) A suborbital rocket used to launch upper atmosphere, exoatmospheric, and microgravity sondes or probes.

An acoustic mirror.

plural of sound mirror