An in-well type acoustic telemetry system includes an elongate tubular housing, an elongate transmitter in the tubular housing, a receiver in the tubular housing, and a spring between the transmitter and the housing biasing the transmitter into acoustic coupling to the housing. The transmitter is adapted to generate an output acoustic signal by linearly fluctuating in response to an electrical signal. The receiver is adapted to generate another electrical signal by linearly fluctuating in response to an input acoustic signal.