An acronym for SOund NAvigation and Ranging. It includes any system that uses underwater sound, or acoustics, for observations and communications. The depth at which minimum sound velocity occurs in the ocean. Twenty times the logarithm to the base 10 of the ratio of the pressure to the reference pressure, in decibels at a specific point. The reference pressure shall be explicitly stated.
Sound speed is the velocity that sound waves travel through a medium.
This change in speed as sound travels through water causes the travel path to bend in the direction of lower velocity. These profiles vary with latitude, season, and time of day. The sound transmitted into the water by a sound source, such as an active sonar ping. Any species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. Threatened species are listed in 50 CFR 17.12.