Says one's piece in a high voice? (6,2)

'says' is the definition.
The answer and definition can be both to do with communicating as well as being verbs in their -s form.
Perhaps there's an association between them I don't understand?

'one's piece in a high voice?' is the wordplay.
I cannot quite see how this works, but
'piece' could be 'p' (abbreviation for Pawn) and 'p' is found within the answer.
'a' is within the answer.
'high' could be 'up' (associated in meaning) and 'up' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?