Brüel & Kjær hydrophones are individually calibrated, waterborne‐sound transducers. The instruments deliver a flat frequency response and are omnidirectional over a wide frequency range. All hydrophones are built with a shielded-element construction; completely waterproof, corrosion-resistant, and are able to withstand high levels of salinity. The instruments provide unrivaled depth, range and precision when measuring sound underwater in the lab - or when conducting ocean research.


Each Brüel & Kjær hydrophone is submitted to an extensive ageing and temperature stabilizing procedure before being individually calibrated. Individual calibration data and frequency response curves are supplied with each hydrophone. The receiving sensitivity calibration of the hydrophones is traceable to international standards.


The frequency response of the four hydrophone types is shown here:

Frequency ResponseFrequency response measurements are made in a water tank in free-field conditions using a Brüel & Kjær PULSE™ calibration system.


B&K Hydrophones deliver great omnidirectional sound measurements. The individual hydrophone directivity patterns in water, are shown here:


Hydrophone dispersion


The polar directivity patterns were measured in free-field conditions achieved by means of gating techniques in a water tank. This method requires a standard hydrophone as a projector and the unknown hydrophone as the receiver for determining the directivity pattern.