10: Audtory System

Question 1

Sound frequency (Hz)

Answer 1

1 hertz = vibration/seconds

Question 2

sound intensity

Answer 2

decibals = loudness

Question 3

What frequency range can the human ear detect?

Answer 3

20Hz to 20,000 Hz

Question 4

What is infrasound?

Answer 4

Any sound with frequency below the audible range of hearing (20Hz)

Question 5

What is ultrasound?

Answer 5

Any sound frequency above the audible range of hearing (20,000Hz)

Question 6

How high can dolphins can frequencies?

Answer 6

200,000Hz

Question 7

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?

Answer 7

1. 5 km/sec (0.9 mi/sec)

4. 5 times as fast as sound travelling though air

Question 8

In water: Contrast the distances travelled in water between lower vs higher frequencies

Answer 8

lower frequency (50Hz) –> lower wavelengths –> travel further

higher frequency (1000Hz) –> shorter wavelengths –> travel not as far

Question 9

In marine environments – which 2 senses are less useful and which becomes more important ?

Answer 9

smell and vision &laquo_space;hearing (more important)

Question 10

In marine mammals (eg. Pinnipeds) who live their lives above and underwater, what additional consideration regarding sound is needed and why?

Answer 10

sound travelling and reacting differently on land than underwater

Question 11

For Odontocete cetaceans, what technique do they use to hunt and determine their surroundings?

Answer 11

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)

Question 12

Are there any disadvantages for echolation in cetaceans?

Answer 12

Yes, double edged sword. allows marinate mammals to survive successfully underwater except it can also cause mortality

Question 13

give 2 examples (one man made; one disease) that affect hearing and describe how this can negatively impact on a toothed whale

Answer 13

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.

Question 14

The hearing organ of ALL mammals consists of what 3 parts?

Answer 14

external ear, middle ear and inner ear

Question 15

External ears

- consist of

Answer 15

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)

Question 16

Middle ear

1. consist of:
2. what is found in the middle ear cavity?
3. what bone houses the middle ear?

Answer 16

1. air filled cavity
2. middle ear
3. malleus, incus, and stapes

Question 17

Inner Ear

1. describe what this consists of:
2. what bone is it encased in?
3. what are the inner ear cavities filled with? -what is the role of the cochlea?
4. describe the structure within the cochlea and how it works.

Answer 17

1. number of vanities within the bone
2. within the petrosal bone
3. perilymph and endolymph
4. 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.

Question 18

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:

Answer 18

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)

Question 19

Describe how polar bears and sea otters hear and any adaptations to their aquatic environment.

Answer 19

similar to terrestrial relatives.

no obvious specialization for hearing of vocalizing underwater

Question 20

Sirenians:

1. Describe their external ear anatomy..
2. What aspect of their ear structure is said to cause a lack of sensitivity and directionality?
3. Do they have ultrasonic capabilities?
4. what is the implications of the above …

Answer 20

1. no external pinna
2. narrow auditory canal
3. structures of middle ear= lack of sensitivity and directionality
4. no ultrasonic capabilities

Question 21

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?

Answer 21

1. Phicdes and odobenidae
2. 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

Question 22

In those pinnipeds with the plexus of arteries and veins located in their middle ear; what diving advantage can this provide?

Answer 22

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.

Question 23

The anatomical features of cetaceans are clearly distinct from those of other marine and terrestrial mammals where is the major difference ?

Answer 23

How sound reaches the middle ear

Question 24

In odontocetes describe the external ear and how sound is conducted to the middle ear:

Answer 24

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.

Question 25

what is the pan bone?

Answer 25

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.

Question 26

Dolphin lower jaw hearing is how many times more sensitive than the external auditory canal?

Answer 26

6 times more sensitive and also 2 area on the side of melon (also for acute hearing)

Question 27

This large fat pad extends backwards to come into contact with a thin walled section of the Middle ear called ______??_________ .

Answer 27

Ectotympanic bone

Question 28

The ectotympanic bone is composed of 2 separate bones what is unique about these bones to the rest of skull?

Answer 28

2 bones have limited in connection to the rest of the skull

Question 29

This and the fact that Odontocete whales have sinuses that surround the ear complex, in effect makes the ear complex ____??__ from the skull

Answer 29

outside or isolated

Question 30

Compare the cartilage connection between Delphinids and other Odontocetes? (look at auditory bulla)

Answer 30

delphiniums = small carriage cone the ear complex to the skull odontocetes = connection is much bigger

Question 31

2 areas on the side of melon are also used for what?

Answer 31

used for acute hearing

Question 32

In Mysticetes compare the ear complex to that of odontocetes with respect to the skull

Answer 32

integrated ito the skull similar to terrestrial mammals

Question 33

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 ??

Answer 33

INDEPENDENT allows for better directional localization of sounds or echoes. act as separate receives.

Question 34

Mysticete 1. do they hear lower or higher frequency sound? 2. What is one way it is thought that they hear via the external system? 3. additional very low freq hearing may come from where?

Answer 34

1. lower frequency sounds 2. seems to transmit sound through a large wax plug that extends into the auditory canal and envelops around a protrusion of tympanic membrane 3. skull bone vibrations caused by low frequency sound waves create an oscillation of the tympanic bull which hands down from the skull.

Question 35

Sound in Marine Mammals is used for what 3 purposes?

Answer 35

communication hunting echolocation

Question 36

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

Answer 36

1. use teeth (clocking) throat poches (bell like sounds) 2. hood and nasal septum for above and below water (breeding, social sounds) above water = moms communications; breeding males, threat calls

Question 37

``` 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? ```

Answer 37

1. social 2. a) whistle b) language c) songs

Question 38

Cetacea; Odontocetes: sound production what structure is responsible for sound and where is it located?

Answer 38

nasa sac system | inside blow hole (whistles, echolocation clicks)

Question 39

Mysticetes: sound production 1. now thought to come from where? 2. What supports this structure? 3. Where does the air come from to do this?

Answer 39

1. U shaped fold in larynx 2. arytenoid cartilage 3. air from laryngeal sac

Question 40

Sirenians 1. What region of the animal do sounds originate from? 2. Describe the type of sound made by them 3. Low freq sound received by ????? And where is this located??

Answer 40

1. frontal region of head 2. similar to whales, short frequency sound (incl; Chirps and squeaks) 3. channel filled with oily song in cheek region of skull

Question 41

Echolocation range varies depending on species: –Sperm whale = ??? –Common dolphin = ?? –Harbor porpoise = ??

Answer 41

1. 6km 2. 100 up to 650 m 3. 25 m

Question 42

Can Mysticete, pinnipeds, Sirenians, sea otters, polar bears echolocate?

Answer 42

NO

Question 43

Phonic Lips (Monkey Lips) 1. 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? 3. What does this structure contribute? 4. What are the sounds that contribute to echolocation called? 5. And how do they aid the animal

Answer 43

1. breaks up the air flow between the lips by opening and closing 2. melon (skull) 3. used to focus and direct the dough forward in the water to locate objects 4. clicks 5. bound off objects

Question 44

Odontocete whales – 1. What is the formal name given for the structure they use to make the sounds associated to echolocation? 2. Where is this structure located ?

Answer 44

1. Monkey Lips Dorsal Bursae (MLDB) | 2. anterior dorsal

Question 45

odontocete vs. mysticete whales | - contrast their hunting style and use of sound

Answer 45

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.