{"thcode":61,"term":{"code":401,"name":"acoustic methods","parent":400,"scope":" measurement of sound propagation in a given medium (such as water) for ranging or acoustical studies."},"uf":[],"bt":[{"code":400,"name":"field observation","parent":398,"scope":"scientific investigation of physical or biological features and processes in a natural setting."},{"code":398,"name":"research method","parent":1,"scope":null},{"code":1,"name":"Marine Realms Information Bank (MRIB) keyword categories","parent":null,"scope":null}],"nt":[{"code":402,"name":"multibeam echo sounder","parent":401,"scope":"acoustic technique for determining sea-floor depths in a wide swath centered below the instrument platform."},{"code":403,"name":"sidescan sonar","parent":401,"scope":"acoustic technique for producing oblique imagery of the sea floor."},{"code":404,"name":"single-beam echo sounder","parent":401,"scope":"acoustic technique for determining sea-floor depth directly below the instrument platform."}],"rt":[]}