I also got tired of the boring wav default icon on my computer which too was just the ♪ on a blank file icon with text, so I decided to class things up.
And who better to honor the more esteemed and my higher quality music files the the classiest (and possibly most snooty (Thank you again Vinyl Scratch Tapes)) Octavia!
I was able to use some freeware, FileTypesMan, that I download from here [link]
which also gave me the instructions on how to replace the icons.
I created this in Illustrator and the font used here is Dizanjnerski font that I also found online and edited a bit to give me more of the classy feel I was looking for.