Sound
Middle English soun, from Anglo-Norman French soun (noun), suner (verb), from Latin sonus . The form with -d was established in the 16th century.
wiktionary
From Middle English sound, sund, isund, ȝesund, from Old English sund, ġesund(“sound, safe, whole, uninjured, healthy, prosperous”), from Proto-Germanic *gasundaz, *sundaz(“healthy”), from Proto-Indo-European *sunt-, *swent-(“vigorous, active, healthy”).
Cognate with Scots sound, soun(“healthy, sound”), Saterland Frisian suund, gesuund(“healthy”), West Frisian sûn(“healthy”), Dutch gezond(“healthy, sound”), Low German sund, gesund(“healthy”), German gesund(“healthy, sound”), Danish sund(“healthy”), Swedish sund(“sound, healthy”). Related also to Dutch gezwind(“fast, quick”), German geschwind(“fast, quick”), Old English swīþ(“strong, mighty, powerful, active, severe, violent”). See swith.
Displaced native Middle English swei, from Old English swēġ, from Proto-Germanic *swōgiz.
From Middle English sound, sund, from Old English sund(“the power, capacity, or act of swimming; swimming; sea; ocean; water; sound; strait; channel”), from Proto-Germanic *sundą(“swimming; sound”), from Proto-Indo-European *swem-(“swimming; sea”). Cognate with Dutch zond(“sound; strait”), Danish sund(“sound; strait; channel”), Swedish sund(“sound; strait; channel”), Icelandic sund(“sound; strait; channel”). Related to swim.
From Middle English sounden, from Old French sonder, from sonde(“sounding line”) of Germanic origin, compare Old English sundgyrd(“a sounding rod”), sundline(“a sounding line”), Old English sund(“water, sea”). More at Etymology 3 above.
etymonline
sound (n.1)
"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."
The unetymological -d was established c. 1350-1550 as part of a tendency to add -d- after -n-. Compare gender (n.), thunder (n.), jaundice (n.), spindle, kindred, riband, and, from French powder (n.), meddle, tender (adj.), remainder, dialectal rundel, rundle for runnel, etc. First record of sound barrier is from 1939. Sound check is from 1977; sound effect is 1909, originally live accompaniment 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.)
"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)
"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)
"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)
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, make a noise" (from PIE root *swen- "to sound"). From late 14c. as "cause something (an instrument, etc.) to produce sound." Related: Sounded; sounding.
