PURPOSE: To improve the S/N ratio of an acoustic measuring apparatus by compensating the phase or delay of the output signal of a number of acoustic wave receivers arranged on one plane to thereby form a number of receiving beams and processing them to thereby calculate the relative position between the sound source and the receiver array.

CONSTITUTION: A number of (more than 4) acoustic receivers 21W2N are arranged on one plane to form an acoustic receiver array 1, which is mounted on a bottom in a ship such as a measuring vessel. After acoustic signals received by the receivers 21W2N are amplified to adequate level by amplifiers 31W3N, respectively, they are applied to a beam former 4 to thereby compensate the delay or phase of the output signals from the amplifiers 31W3N. Then, these signals are added to simultaneously form a number of received beams B1WBM having main lobes so that their sensitivity becomes maximum only for the plane wave incident from certain direction toward the center of the array 1 to thereby produce acoustic signal intensities SP1WSPm obtained by the beams B1WBM having slightly different directions of their main lobes to a selector 5.