21:38 Mar 4, 2011 

Is singular, not plural. If you must use a plural, then it's "percussion instruments."

19:24 Mar 4, 2011 

Oh, I hadn't thought of "a company selling musical instruments and related items"! I was thinking "voice" (in the context of a conservatory), but a music store is probably dealing with "songs." So IMO, context still matters. ;-)

19:13 Mar 4, 2011 

Depending on the context , could be " vocal " or "song"

19:07 Mar 4, 2011 

I actually think we have enough context - it's a job title, presumably a company selling musical instruments and related items.

18:38 Mar 4, 2011 

So far, there are three answers – all possible, in one context or another. What's your context, please? Is it a music school, a nursery school, a camp, a marching bank (not likely, with claviers, but I'm hardly ever sure of anything anymore), etc. Thanks in advance! :-)