Acoustic beamforming can be implemented using electronic circuitry or an acoustic lens. Electronic beamforming uses a transducer array coupled with analog or digital signal processing circuitry to form beams. Sum and delay beamforming and narrowband phase-shift beamforming are two widely used algorithms implemented by the circuitry. The amount of signal processing circuitry and required power both increase with the number of transducers. This becomes a critical problem when large arrays are needed, especially for portable systems such as diver-held or autonomous underwater vehicle sonar systems.
Acoustic lenses implement beamforming with minimal associated circuitry.
An acoustic lens focuses sound in much the same way that an optical lens focuses light. Snell's law describes the refraction of sound as it passes through an interface between two materials of differing sound speed. An acoustic lens provides the appropriate material thicknesses that focus a parallel wavefront of sound to a single focal point. Either type may be a compound lens, with multiple layers of materials of differing refractive indices. Compound lens systems can be designed to optimally focus sound from several source directions or to reduce the sensitivity of the system to varying ambient temperatures.