Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may include exciting a plurality of signal source pairs having a substantially equal and non-zero acoustic signature amplitude difference in a frequency domain to provide acoustic signal data, and acquiring the acoustic signal data along a selected azimuth. The plurality of signal source pairs may comprise acoustic bender plates, perhaps included in the outer wall of a downhole tool.

Abstract: A system and method for determining blockage in a wellbore containing fluid and/or in a formation adjacent the wellbore, according to which energy is generated in the fluid and variables associated with the energy are measured.