A method for controlling configuration of an air interface between an access node and at least one user equipment device (UE), where the air interface is divided over time into frames and the frames are further divided at least into subframes, where the air interface operates in accordance with a time-division-duplex (TDD) configuration that defines at least a number of uplink subframes per frame for communication over the air interface. An example method includes (i) detecting at least a threshold high rate of uplink voice muting on the air interface, and (ii) responsive to at least the detecting, changing the TDD configuration to increase the number of uplink subframes per frame over the air interface.