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)
Describe how polar bears and sea otters hear and any adaptations to their aquatic environment.
similar to terrestrial relatives.
no obvious specialization for hearing of vocalizing underwater
Sirenians:
- Describe their external ear anatomy..
- What aspect of their ear structure is said to cause a lack of sensitivity and directionality?
- Do they have ultrasonic capabilities?
- what is the implications of the above …
- no external pinna
- narrow auditory canal
- structures of middle ear= lack of sensitivity and directionality
- no ultrasonic capabilities
Pinnipeds:
The anatomy of pinnipeds are similar to terrestrial mammals with some modification: 1. Which pinniped groupings have no pinnae?
2. What 3 main adaptations do they have and what does this allow them to hear?
- Phicdes and odobenidae
- a) tympanic bulla or bone (Where the middle ear is located) is very large = middle ear cavity is later than other marine mammals. (able to hear lower frequencies better on land)
b) middle ear bones are enlarged (3 ossicles) = bone conductive hearing
c) plexus of arteries and veins = assists n higher frequencies
In those pinnipeds with the plexus of arteries and veins located in their middle ear; what diving advantage can this provide?
deep diving;
plexus can be inflated which reduces the airspace of the middle ear cavity. This increase the pressure within the cavity thereby matching outside ambient pressures.
The anatomical features of cetaceans are clearly distinct from those of other marine and terrestrial mammals where is the major difference ?
How sound reaches the middle ear
In odontocetes describe the external ear and how sound is conducted to the middle ear:
the external ear has NO pinna, although their E.A.M. is present it has become a very narrow tube that is closed.
sound is conducted to the middle ear through their mandibles! or jawbone.
what is the pan bone?
the posterior part of the mandible beyond the teeth, is the walled.
the part of the mandible is concaved to form a hollow –> contains tissue –> fat pad or channel.
Dolphin lower jaw hearing is how many times more sensitive than the external auditory canal?
6 times more sensitive and also 2 area on the side of melon (also for acute hearing)
This large fat pad extends backwards to come into contact with a thin walled section of the Middle ear called ______??_________ .
Ectotympanic bone
The ectotympanic bone is composed of 2 separate bones what is unique about these bones to the rest of skull?
2 bones have limited in connection to the rest of the skull
This and the fact that Odontocete whales have sinuses that surround the ear complex, in effect makes the ear complex ____??__ from the skull
outside or isolated
Compare the cartilage connection between Delphinids and other Odontocetes?
(look at auditory bulla)
delphiniums = small carriage cone the ear complex to the skull
odontocetes = connection is much bigger
2 areas on the side of melon are also used for what?
used for acute hearing
In Mysticetes compare the ear complex to that of odontocetes with respect to the skull
integrated ito the skull similar to terrestrial mammals
All of these adaptations allow for both ears to be ______??________ of each other.
What does this allow for in assessing sound and how does this help cetaceans ??
INDEPENDENT
allows for better directional localization of sounds or echoes.
act as separate receives.
Mysticete
- do they hear lower or higher frequency sound?
- What is one way it is thought that they hear via the external system?
- additional very low freq hearing may come from where?
- lower frequency sounds
- seems to transmit sound through a large wax plug that extends into the auditory canal and envelops around a protrusion of tympanic membrane
- skull bone vibrations caused by low frequency sound waves create an oscillation of the tympanic bull which hands down from the skull.
Sound in Marine Mammals is used for what 3 purposes?
communication
hunting
echolocation
Pinnipeds
Created by larynx but also use other structures to produce sound:
1. male walrus: describe 2 other structures that they use for sound production and what sounds they make
2. Hooded seals: what other structures do they use for sound production and for what 2 purposes?
Contrast above and below water vocalization purposes
- use teeth (clocking) throat poches (bell like sounds)
- hood and nasal septum for above and below water (breeding, social sounds)
above water = moms communications; breeding males, threat calls
Cetacea 1. What is sound mainly used for? 2. Describe the common type of sound for the following: a)Dolphin? B)Killer whale? C) Humpback whale?
- social
- a) whistle
b) language
c) songs
Cetacea;
Odontocetes: sound production
what structure is responsible for sound and where is it located?
nasa sac system
inside blow hole (whistles, echolocation clicks)
Mysticetes: sound production
- now thought to come from where?
- What supports this structure?
- Where does the air come from to do this?
- U shaped fold in larynx
- arytenoid cartilage
- air from laryngeal sac
Sirenians
- What region of the animal do sounds originate from?
- Describe the type of sound made by them
- Low freq sound received by ????? And where is this located??
- frontal region of head
- similar to whales, short frequency sound (incl; Chirps and squeaks)
- channel filled with oily song in cheek region of skull
Echolocation range varies depending on species:
–Sperm whale = ???
–Common dolphin = ??
–Harbor porpoise = ??
- 6km
- 100 up to 650 m
- 25 m
Can Mysticete, pinnipeds, Sirenians, sea otters, polar bears echolocate?
NO
Phonic Lips (Monkey Lips)
- Describe how these contribute to echolocation and what they are responsible for - 2. What is the name of the structure where the sounds goes from phonic lips?
- What does this structure contribute?
- What are the sounds that contribute to echolocation called?
- And how do they aid the animal
- breaks up the air flow between the lips by opening and closing
- melon (skull)
- used to focus and direct the dough forward in the water to locate objects
- clicks
- bound off objects
Odontocete whales –
- What is the formal name given for the structure they use to make the sounds associated to echolocation?
- Where is this structure located ?
- Monkey Lips Dorsal Bursae (MLDB)
2. anterior dorsal
odontocete vs. mysticete whales
- contrast their hunting style and use of sound
odontocetes use loud blasts (bangs) = temporarily stun or disorientate their prey
mysticetes use bubble netting technique to hunt and capture prey
NO sound is used.
