Abstract: In order to accumulate data from which the signature of an array of n interacting seismic sources 21 to 27, for instance marine seismic sources in the form of air guns, can be determined, the array is actuated and the emitted pressure wave is measured at n independent points whose positions will respect to the array are known by hydrophones 31 to 37. Data from the measured pressure wave is stored for subsequent processing to produce n equivalent signatures of the n sources taking into account the interactions therebetween. The signature of the array is then determined merely by superposing the n equivalent signatures.

Abstract: A hydrophone section for a seismic streamer towed array in which the hydrophones 2 are arranged in groups of not more than 7, the spacing of the hydrophones within each group being such that each group has an overall length l=0.8-1.2 m. The hydrophone mounts 5 and mechanical spacers 3 are attached at their periphery to aramid fibre strainwires 4. The hydrophone mounts and mechanical spacers are acoustically open structures.

Abstract: A mechanical spacer for locating electrical cables and strain ropes within the outer sheath of a towed acoustic array. The spacer has arcuate strip sections 10 joined by intervening portions 11 which form radially outwardly facing U-shaped recesses 12. Electrical cables are laid loosely in the center part of the spacer, located if required by projecting support webs 15. Strain ropes are secured in the recesses 12 by spring clips (not shown). Resilient tubular structures 14 are formed on the web sections 10 to locate the spacer within the towed array sheath 20.