A [[well log]] of the [[interval transit time]]: i.e., the time required for a [[compression wave]] to travel one foot in the [[formation]] (generally in microseconds per foot); the reciprocal of the compressional velocity. The borehole compensated sonic [[sonde]] carries two sets of [[transducer|transducers]], one with its [[transmitter]] above its [[receiver]] pair and one with its transmitter below. The transmitters are pulsed alternately, and the alternate measurements are averaged. Spurious effects caused by borehole-size changes, and sonde tilt, which would affect a measurement with a single set of transducers, are thereby substantially reduced.

{{ :terms:glsp14f1.gif }}