Acoustic signature (Physics & Chemistry)
From The Encyclopedia of Earth
Typical acoustic signatures of bottomfish, mostly snappers and approximately 30-60 cm long, at 70 kHz frequency during day and nighttime surveys. Figure by Réka Domokos. Source: NOAA
Contents
Acoustic signature
March 28, 2010, 12:00 am
December 12, 2011, 5:37 pm
An acoustic signature is a set of characteristics used to describe a sound signal which is being observed.
| This article is written at a definitional level only. Authors wishing to improve this entry are inivited to expand the present treatment, which additions will be peer reviewed prior to publication of any expansion. |
The acoustic signature may present itself in a gas, liquid or solid medium; furthermore, its temporal nature may be of a repeating waveform, be intermittent, or manifest as a single burst.
The signature may arrive directly from an emission source, or may include sound echos from targets, radiated and ambient noise, with salient echo characteristics including target strength, spectral reflectivity versus frequency, doppler shift, doppler spread and target range extent.
Characteristics of the signature
The acoustical signature generally may be characterized by its:
- Energy content or amplitude
- Frequency spectrum content
- Intermittence or continuity
- Transmission medium
- Directional vector of the transmission
- Presence or absence of echoes
Applications
There are countless applications of an acoustical signature, some of the prominent ones being:
- Voice recognition (identification of a specific person or animal producing an acoustic signature)
- Navigation of certain marine mammals or other aquatic fauna (use of echolocation via underwater topography)
- Prey location of certain marine mammals or other aquatic fauna (echolocation using prey backscatter)
- Military intercept systems (passive monitoring of missile launches, telemetry communications, etc.)
References
- C.S.Clay and H.Medwin. 1977. Acoustical Oceanography. Wiley, New York
- National Research Council of the National Academies (U.S.) 2003. Ocean Noise and Marine Mammals. The National Academies Press, Washington DC
- D.Simmonds and J.MacLennan. 2005. Fisheries Acoustics: Theory and Practice, 2nd edition. Blackwell, Oxford.
See also
- Noise pollution
- Physical Oceanography Index
