10: Audtory System Flashcards
Sound frequency (Hz)
1 hertz = vibration/seconds
sound intensity
decibals = loudness
What frequency range can the human ear detect?
20Hz to 20,000 Hz
What is infrasound?
Any sound with frequency below the audible range of hearing (20Hz)
What is ultrasound?
Any sound frequency above the audible range of hearing (20,000Hz)
How high can dolphins can frequencies?
200,000Hz
Sound waves travel through water at a speed of about ????
Compare this to speed in air is it faster or slower and by how much?
- 5 km/sec (0.9 mi/sec)
4. 5 times as fast as sound travelling though air
In water: Contrast the distances travelled in water between lower vs higher frequencies
lower frequency (50Hz) –> lower wavelengths –> travel further
higher frequency (1000Hz) –> shorter wavelengths –> travel not as far
In marine environments – which 2 senses are less useful and which becomes more important ?
smell and vision «_space;hearing (more important)
In marine mammals (eg. Pinnipeds) who live their lives above and underwater, what additional consideration regarding sound is needed and why?
sound travelling and reacting differently on land than underwater
For Odontocete cetaceans, what technique do they use to hunt and determine their surroundings?
echolocation = detect of an object by means of reflected sound.
requires various organs; some to produce the sound, some to receive it, and others to developer their meaning
(200,000 hz or 200kHz)
Are there any disadvantages for echolation in cetaceans?
Yes, double edged sword. allows marinate mammals to survive successfully underwater except it can also cause mortality
give 2 examples (one man made; one disease) that affect hearing and describe how this can negatively impact on a toothed whale
dolphins who suffer from an infection of middle ear nematodes can die of starvation (unable to detect food)
man made noises can deprive cetaceans of their hearing ability thereby causing death through damage to their ears or various other organs and tissues.
The hearing organ of ALL mammals consists of what 3 parts?
external ear, middle ear and inner ear
External ears
- consist of
pinna that is attached to the external auditory meatus (air filled tube on land or water filled when subjmerged) that terminates at the tympanic membrane (ear drum)
Middle ear
- consist of:
- what is found in the middle ear cavity?
- what bone houses the middle ear?
- air filled cavity
- middle ear
- malleus, incus, and stapes
Inner Ear
- describe what this consists of:
- what bone is it encased in?
- what are the inner ear cavities filled with? -what is the role of the cochlea?
- describe the structure within the cochlea and how it works.
- number of vanities within the bone
- within the petrosal bone
- perilymph and endolymph
- long hollow rolled up organ that has 3 ducts cone to this is the neural membrane which help transit signals to the vestibule-chcolear nerve (CN8) which transmits the signals to the brain.
Processing of sound:
Describe how a sound wave is processed from when it reaches the outer aspect of the auditory system all the way to brain:
pinna collects the sound –> sound travels through hotel external auditory meatus and causes the tympanic membrane to oscillate, this oscillation will cause the 3 bones in the middle ear to oscillate The stapes is cone to the oval window which transmit the sound from waves into the perilymph and enolypmh where it will cause the fluid to move and the tiny hair cells on the basal membrane of the cochlear will release neurotransmitters one brain to activate and ap.
(apex of the cochlea= low frequencies; base of cochlea = high frequencies)