I've seen pianists carefully put a mirror in front of them on an upright piano so they can see people trying to get their attention from behind without taking their eyes off the keyboard.  (That's definitely helpful when a caller is trying to signal "three more times" or whatever.) 

Also you can make sure whoever *is* next to the pianist is playing an instrument that doesn't keep them from repeating signals audibly.  (Harder for flute/whistle to reliably say "three more!" than fiddle/guitar/mando/bass.)

-- Alan

On 9/20/18 1:17 PM, Yaron Shragai via Musicians wrote:
Any best methods for communicating, during performance, with a pianist playing an upright piano, who is therefore looking towards the piano and away from you?  (Esp. as a bandleader who is not necessarily positioned next to the pianist)


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