Acoustical intelligence

Acoustical intelligence (ACOUSTINT, sometimes ACINT) is an intelligence gathering discipline that collects and processes acoustic phenomena. It is a subdiscipline of MASINT (measurement and signature intelligence).

This uses broadband and narrowband analysis of acquired acoustic signatures from surface ships and submarines, although it can also be used for low-flying aircraft such as helicopters. Broadband analysis concerns the overall noise created by a platform, whereas narrowband analysis examines the spectra of the received energy at a more precise level.

Broadband analysis is useful for identifying any vessel at a long range, whereas narrowband analysis is generally more useful for identifying the category, type and ideally the individual vessel name. The category might be, for example, differentiating between a commercial vessel and a warship; the type might be narrowing this down to an individual class and hence identifying nationality, and the individual name might identify the specific ship or submarine.