how to put the music in playlist cached by certain

Hi.
How i can put the music in cache for a days? It can lower the site traffic.
Any contribution?

I try modify the .htaccess for this:

<FilesMatch "\.(mp3|m4a|flv)$">
Header set Cache-Control "max-age=604800"
</FilesMatch>

But don't work, the page apears 500 internal server error.