A highly sensitive sing‐around system was developed for ultrasonic velocity measurements in solids. In the developed system, a selected cycle of a selected echo is gated out, to retrigger the transmitter. Highly stable circuitry is employed. The timing system incorporates two modified commercial electronic counters and associated circuitry to maximize stability and detection sensitivity. Environmentally induced sample velocity changes of the order one part in 107 may be detected, provided that the accompanying attenuation change is negligible, or that steps taken to compensate for ultrasonic attenuation changes by adjusting electronic attenuation, produce phase shifts which are known to sufficient accuracy.