Simplify the following text for a Grade 7 native English-speaking person.
Original: A tuning fork or electronic tuning device may be used as a reference pitch , though in ensemble rehearsals often a piano is used ( as its pitch can not be adjusted for each rehearsal ) .
Simplified: If they are not tuning to a piano , players of instruments sometimes use a tuning fork which gives an exact note ( usually an A ) so that they know they are in tune . There are also electronic tuning devices .