Echolocation And Sound Flashcards
(13 cards)
How does frequency of sounds effect the wavelengths?
Lower frequency sounds have longer wavelengths and travel much further
Higher frequency sounds have shorter wavelengths and gets attenuated quickly
What type of frequencies do odontocetes and mysticetes have?
Odontocetes typically use higher-frequencies
Mysticetes typically use lower frequencies
How do odontocetes make sound?
- Air supply is controlled by the larynx (going from the lungs to the nasal passage)
- Air flow pressurises the phonic lips, which open and slap shut, causing the dorsal bursae to vibrate creating sound
- Outgoing sounds are projected forward by reflecting off of air sacs.
How do odontocetes hear sounds?
Sounds are received by the lower jaw bone and transmitted through the mandibular fat pad to auditory bullae
The inner and middle ear structures are isolated from the skull (housed within air sinuses in auditory bullae), enabling directional hearing
How do mysticetes make sound?
Sounds are produced by vibration in the larynx (similar to terrestrial mammals:
- Lungs push are through the larynx
- Sound is produced by the vibration of cricoid cushion and transverse arrtenoid folds (TAFs) - both unique to mysticetes
How do mysticetes hear sound?
Likely via bone conduction (vibrations of the skull to the inner ear, bypassing the middle ear)
- Bones housed in the middle ear and inner ear are partly isolated from the skull with sinuses (but directional hearing not as good as odontocetes)
How do pinnipeds make sound?
Sounds in air are produced by air flow through the larynx
Sounds in the water are produced by air being shunted between the lungs and nasal structures -> sound produced by vibration of tracheal membranes.
How do pinnipeds hear sound?
Air: via tympanic membrane and ossicles chain
Water: via bone conduction (same as in mysticetes)
What do cetaceans use sound for?
Orientation - listening to environmental sounds
Echolocation - foraging and navigation
Communication
What prey species produce strong echoes?
Fish with swim bladders
What is echolocation?
An acoustic “picture” of their surroundings:
- Emit and wait for echo to return before emitting the next click
- Echo delay gives target range
- Echo characteristics give information on target type
How can inter pulse interval be used yo reveal the size of sperm whales?
The difference between p0 and p1 is the time taken for the click to travel twice the length of the whales head. This can be used as a proxy for the length of the whales head - IPI is a relative measure of wavelength
Provide the details of the song of the Humpback whale:
- Full song is only done by males, usually during the breeding season
- Organised into hierarchical units
- All males in the same area sing the same song (culture)
- Different breeding areas have different song
- Songs evolve during the season and all signers keep up
