sound (n.1) Look up sound at Dictionary.com
"noise, what is heard, sensation produced through the ear," late 13c., soun, from Old French son "sound, musical note, voice," from Latin sonus "sound, a noise," from PIE *swon-o-, from root *swen- "to sound" (source also of Sanskrit svanati "it sounds," svanah "sound, tone;" Latin sonare "to sound;" Old Irish senim "the playing of an instrument;" Old English geswin "music, song," swinsian "to sing;" Old Norse svanr, Old English swan "swan," properly "the sounding bird").

The terminal -d was established c. 1350-1550 as part of a tendency to add -d- after -n-. Compare gender (n.), thunder (n.), jaundice (n.), kindred. First record of sound barrier is from 1939. Sound check is from 1977; sound effects is 1909, originally live accompaniments to silent films.
The experts of Victor ... will ... arrange for the synchronized orchestration and sound effects for this picture, in which airplane battles will have an important part. ["Exhibitor's Herald & Moving Picture World," April 28, 1928]
sound (adj.) Look up sound at Dictionary.com
"free from special defect or injury," c. 1200, from Old English gesund "sound, safe, having the organs and faculties complete and in perfect action," from Proto-Germanic *sunda-, from Germanic root *swen-to- "healthy, strong" (source also of Old Saxon gisund, Old Frisian sund, Dutch gezond, Old High German gisunt, German gesund "healthy," as in the post-sneezing interjection gesundheit; also Old English swið "strong," Gothic swinþs "strong," German geschwind "fast, quick"), with connections in Indo-Iranian and Balto-Slavic. Meaning "right, correct, free from error" is from mid-15c. Meaning "financially solid or safe" is attested from c. 1600; of sleep, "undisturbed," from 1540s. Sense of "holding accepted opinions" is from 1520s.
sound (v.2) Look up sound at Dictionary.com
"fathom, probe, measure the depth of," mid-14c. (implied in sounding), from Old French sonder, from sonde "sounding line," perhaps from the same Germanic source that yielded Old English sund "water, sea" (see sound (n.2)). Barnhart dismisses the old theory that it is from Latin subundare. Figurative use from 1570s.
sound (n.2) Look up sound at Dictionary.com
"narrow channel of water," c. 1300, from Old Norse sund "a strait, swimming," or from cognate Old English sund "act of swimming, stretch of water one can swim across, a strait of the sea," both from Proto-Germanic *sundam-, from *swum-to-, suffixed form of Germanic root *swem- "to move, stir, swim" (see swim (v.)).
sound (v.1) Look up sound at Dictionary.com
early 13c., sounen "to be audible, produce vibrations affecting the ear," from Old French soner (Modern French sonner) and directly from Latin sonare "to sound" (see sonata). From late 14c. as "cause something (an instrument, etc.) to produce sound." Related: Sounded; sounding.