The site probably gave you that because "oto" is sound and "ko" is child. But it is hilarious because "otoko" itself means man. 

Anyway as for names. there are quite a lot of Japanese names that have something to do with sound. For example there is Ayane (kanji for color + kanji for sound), Kanon (flower + sound), Akane (red + sound) etc. Are you looking for a male or female name?