The well developed techniques of coherent detection and signal averaging may be used to extend the range and accuracy of measurements of ultrasonic velocity and attenuation. Significant improvements in signal‐to‐noise ratio are obtained by averaging a coherently detected echo train in a signal averager such as a multichannel analyzer or boxcar integrator. A standard circuit of this type is described and analyzed. Comparison of coherent detection and rectification shows the inherent advantages of coherent detection for signal‐to‐noise enhancement.