Here's why:
* Homograph: It has the same spelling but different meanings and pronunciations:
* Sound (as in noise): pronounced /saʊnd/
* Sound (as in healthy): pronounced /saʊnd/
* Homonym: It has the same pronunciation and spelling but different meanings:
* Sound (as in noise): pronounced /saʊnd/
* Sound (as in healthy): pronounced /saʊnd/
Therefore, "sound" fits both definitions, making it both a homograph and a homonym.