Echolocation is the use of sound as a form of navigation.
Echolocation, also called bio sonar, is a biological active sonar used by several animal groups, both in the air and underwater. Echolocating animals emit calls and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects. Echolocation is used for navigation, foraging, and hunting prey.
Microbats constitute the suborder Microchiroptera within the order Chiroptera (bats). Bats have long been differentiated into Megachiroptera (megabats) and Microchiroptera, based on their size, the use of echolocation by the Microchiroptera and other features; molecular evidence suggests a somewhat different subdivision, as the microbats have been shown to be a paraphyletic group.
Human echolocation is the ability of humans to detect objects in their environment by sensing echoes from those objects, by actively creating sounds: for example, by tapping their canes, lightly stomping their foot, snapping their fingers, or making clicking noises with their mouths. People trained to orient by echolocation can interpret the sound waves reflected by nearby objects, accurately identifying their location and size.
Bioacoustics is a cross-disciplinary science that combines biology and acoustics. Usually it refers to the investigation of sound production, dispersion and reception in animals. This involves neurophysiological and anatomical basis of sound production and detection, and relation of acoustic signals to the medium they disperse through. The findings provide clues about the evolution of acoustic mechanisms, and from that, the evolution of animals that employ them.
Sound localization is a listener's ability to identify the location or origin of a detected sound in direction and distance.
The brown long-eared bat or common long-eared bat is a small Eurasian insectivorous bat. It has distinctive ears, long and with a distinctive fold. It is extremely similar to the much rarer grey long-eared bat which was only validated as a distinct species in the 1960s. An adult brown long-eared bat has a body length of 4.5–4.8 cm, a tail of 4.1–4.6 cm, and a forearm length of 4–4.2 cm. The ears are 3.3–3.9 cm in length, and readily distinguish the long-eared bats from most other bat species. They are relatively slow flyers compared to other bat species.
The tragus is a small pointed eminence of the external ear, situated in front of the concha, and projecting backward over the meatus. It also is the name of hair growing at the entrance of the ear. Its name comes the Ancient Greek tragos, meaning 'goat', and is descriptive of its general covering on its under surface with a tuft of hair, resembling a goat's beard. The nearby antitragus projects forwards and upwards.
The Egyptian fruit bat or Egyptian rousette is a species of megabat that is found in Africa, the Middle East, the Mediterranean, and the Indian subcontinent. It is one of three Rousettus species with an African-Malagasy range, though the only species of its genus found on continental Africa. The common ancestor of the three species colonized the region in the late Pliocene or early Pleistocene. The species is traditionally divided into six subspecies. It is considered a medium-sized megabat, with adults weighing 80–170 g (2.8–6.0 oz) and possessing wingspans of approximately 60 cm (24 in). Individuals are dark brown or grayish brown, with their undersides paler than their backs.
Acoustic location is a method of determining the position of an object or sound source by using sound waves. Location can take place in gases, liquids, and in solids.
Whitlow W. L. Au was a leading expert in bioacoustics specializing in biosonar of odontocetes. He is author of the widely known book The Sonar of Dolphins (1993) and, with Mardi Hastings, Principles of Marine Bioacoustics (2008). Au was honored as a Fellow of the Acoustical Society of America in 1990 and awarded the ASA's first Silver Medal in Animal Bioacoustics in 1998. He was graduate advisor to MacArthur Fellow Kelly Benoit-Bird, who credits Au for discovering how sophisticated dolphin sonar is, developing dolphin-inspired machine sonars to separate different species of fish with the goal of protecting sensitive species, and for making numerous contributions to the description of Humpback whale song, which helped protect these whales from ship noise and ship traffic.
Bat detectors are the most common way to identify the species of flying bats. There are distinct types of call which can indicate the genus, and variations in pattern and frequency which indicate the species. For readers not familiar with the different types of bat detector, there is further information below and elsewhere.
Active sensory systems are sensory receptors that are activated by probing the environment with self-generated energy. Examples include echolocation of bats and dolphins and insect antennae. Using self-generated energy allows more control over signal intensity, direction, timing and spectral characteristics. By contrast, passive sensory systems involve activation by ambient energy. For example, human vision relies on using light from the environment.
Onychonycteris is the more primitive of the three oldest bats known from complete skeletons, having lived in the area that is current day Wyoming during the Eocene period, 52.5 million years ago.
Bats are flying mammals of the order Chiroptera. With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most birds, flying with their very long spread-out digits covered with a thin membrane or patagium. The smallest bat, and arguably the smallest extant mammal, is Kitti's hog-nosed bat, which is 29–34 millimetres in length, 150 mm (6 in) across the wings and 2–2.6 g in mass. The largest bats are the flying foxes, with the giant golden-crowned flying fox reaching a weight of 1.6 kg and having a wingspan of 1.7 m.
Ultrasound avoidance is an escape or avoidance reflex displayed by certain animal species that are preyed upon by echolocating predators. Ultrasound avoidance is known for several groups of insects that have independently evolved mechanisms for ultrasonic hearing. Insects have evolved a variety of ultrasound-sensitive ears based upon a vibrating tympanic membrane tuned to sense the bat's echolocating calls. The ultrasonic hearing is coupled to a motor response that causes evasion of the bat during flight.
When an echolocating bat approaches a target, its outgoing sounds return as echoes, which are Doppler shifted upward in frequency. In certain species of bats, which produce constant frequency (CF) echolocation calls, the bats compensate for the Doppler shift by changing their call frequency as they change speed towards a target. This keeps the returning echo in the same frequency range of the normal echolocation call. This dynamic frequency modulation is called the Doppler shift compensation (DSC), and was discovered by Hans Schnitzler in 1968.
Echolocation systems of animals, like human radar systems, are susceptible to interference known as echolocation jamming or sonar jamming. Jamming occurs when non-target sounds interfere with target echoes. Jamming can be purposeful or inadvertent, and can be caused by the echolocation system itself, other echolocating animals, prey, or humans. Echolocating animals have evolved to minimize jamming, however; echolocation avoidance behaviors are not always successful.
Ernest Glen Wever was an American experimental psychologist known for his elucidation of hearing in vertebrates, ranging from the biomechanical functioning of the cochlea to the neural coding of sound and the evolutionary biology of hearing.
Annemarie Surlykke was a Danish physiologist. She contributed significantly to bioacoustic research, in particular in the fields of insect hearing and acoustic communication, bat echolocation and insect-bat interactions. Graduated from University of Southern Denmark, employments at University of Tübingen and Aarhus University. From 1987 associate professor at University of Southern Denmark, full professor in 2011.
