1. A method for actively monitoring temperature in a combustor of a gas turbine engine, comprising: placing in a gas turbine combustor at least one acoustic transmitter and at least one thermoacoustic sensor that is oriented in a distinct line-of-sound path from the transmitter, the sensor capable of generating sensor output signals indicative of thermoacoustic oscillations, including combustion thermoacoustic oscillations; coupling the at least one transmitter and the at least one sensor to a controller that is capable of causing the at least one transmitter to transmit acoustic signals within the combustor and capable of correlating sensor output signals with combustion conditions, including at least combustion temperature; transmitting acoustic signals from the at least one transmitter; receiving the acoustic signals from the at least one acoustic transmitter and generating dynamic sensor output signals with the at least one thermoacoustic sensor that includes contributions of the received acoustic signals; determining a time-of-flight for the acoustic signals traveling along each of the line of sound paths; and processing the time-of-flight for the acoustic signals traveling along the line of sound paths to determine respective combustor path temperature along each respective line-of-sound path.