Do you have to attribute the sound within the work? Or can you do if from the site where the work is hosted?
No, you do not have to attribute within the work itself.
Preferably the credit should be closely associated to the work. But it is OK to link to another page or source where the attribution is stated. Usually people aren't fussy exactly how they are credited, as long as it's visible somewhere.
For full details, visit the attribution section in our FAQ here: