a method for developing an acoustical well log which displays the frequency content of a broad spectrum acoustical signal by discrete windows of the frequency spectrum , the final display being developed concurrently with the taking of the log and being shown with respect to depth . the method employs a spectrum analyzer and , in a single receiver embodiment , a correction circuit for compensating for attenuation introduced by the communication cable from the well - logging sonde to the surface where the recordings are produced . a two receiver embodiment develops and displays the frequency content as amplitude differences at a plurality of frequencies , automatically compensating for cable attenuation .