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ZOOL 342 > Echolocation > Flashcards

Echolocation Flashcards

1
Q

What is echolocation?

A

emission of acoustic signals in order to use the returning echoes to perceive the environment

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2
Q

echo ______, ________________, and ____________ and ___________________ differences enable an animal to determine azimuth and distance.

A
  • delays
  • intensity
  • frequency
  • left-and-right
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3
Q

List the following for megachiroptera:
- what kind of animals
- large or small?
- visual or non-visual?
- echolocating or non-echolocating?

A
  • flying foxes and fruit bats
  • fairly large
  • primarily visual
  • 1 echolocating species
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4
Q

List the following for microchiroptera:
- what kind of animals
- large or small?
- visual or non-visual?
- echolocating or non-echolocating?

A
  • “typical” bats
  • most are small
  • vision relatively poor
  • all echolocate
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5
Q

What kind of frequencies does bat echolocation depend on?

A

ultrasound

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6
Q

What is the range of bat echolocation in dB?

A

60-140 dB

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7
Q

Is call duration long or short?

A

short

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8
Q

TRUE or FALSE: Slow attenuation of high frequencies also results in greater changes in the power of returning echoes.

A

FALSE: RAPID attenuation

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9
Q

What features can be determined from echoes?

A
  1. distance
  2. subtended angle
  3. absolute size
  4. azimuth
  5. elevation
  6. velocity
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10
Q

TRUE or FALSE: very small amplitude + short delay = small insect is nearby

A

TRUE

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11
Q

TRUE or FALSE: very small amplitude + long delay = large object is nearby

A

FALSE: large object is FAR AWAY

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12
Q

How do bats use distance to echolocate?

A

compare the time between a call and its returning echo

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13
Q

How do bats use subtended angle to echolocate?

A

the intensity of the echo dictates how much of the echolocating call is broken by an object

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14
Q

How do bats use echolocation to determine absolute size of an object?

A

by combing DELAY and INTENSITY, the absolute size of an object can be calculated

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15
Q

How do bats use echolocation to determine the azimuth?

A

compare INTENSITY and TIMING differenes between LEFT and RIGHT to determine direction in x-y dimensions

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16
Q

How do bats use echolocation to determine elevation?

A
  • can move ears when receiving echoes to compare intensities between ears
  • ear structure can also enhance intensity differences
  • together these provide info on z-axis (up-down)
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17
Q

How do bats use echolocation to determine velocity?

A

doppler shift of echoes yields velocity

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18
Q

TRUE or FALSE: echo is higher frequency than call = target is moving further away from bat

A

FALSE: bat is gaining on target (hint: doppler shift)

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19
Q

label the following on slide 8 diagram:
- absolute size
- azimuthal angle
- elevation
- doppler shift and flutter

A

slide 8

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20
Q

Put the following in order of when a bat’s calls get closer in time:
- search phase
- terminal buzz phase
- approach phase

A
  1. search phase
  2. approach phase
  3. terminal buzz phase
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21
Q

What are 3 types of echolocating calls?

A
  1. clicks
  2. constant frequency (CF)
  3. frequency modulation (FM)
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22
Q

Describe the characteristics of clicks.

A
  • broad spectrum; not ultrasonic
  • found in the single echolocating fruit bat and birds
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23
Q

Describe the characteristic of constant frequency calls.

A

primarily a single frequency

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24
Q

Describe the characteristic of frequency modulation (FM) calls.

A

frequency sweeps

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25
Q

Draw a frequency-time graph for FM bats. Label the 3 phases of the call.

A

graph A on slide 12 (frequency sweeps)

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26
Q

Draw a frequency-time graph for CF-FM bats. Label the 3 phases of the call.

A

graph B on slide 12 (downward sweep at end)

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27
Q

Where do FM bats typically forage?

A

in open areas or on forest edges

28
Q

TRUE or FALSE: CF-FM bat calls tend to be high intensity to ensure that echoes from targets can be received.

A

FALSE: FM bats

29
Q

TRUE or FALSE: CF-FM bats tend to have shorter duration calls, whereas FM bats tend to have longer duration calls

A

FALSE:
- CF-FM = longer call
- FM = shorter call

30
Q

Why do FM bats have a shorter duration, broad frequency call?

A

the sweep of the call allows for BETTER RESOLUTION of the TIME DELAY between the call and echo

31
Q

TRUE or FALSE: CF-FM bats use harmonics to make their echolocation even more precise.

A

FALSE: FM bats

32
Q

TRUE or FALSE: CF-FM bat calls tend to be longer and the operational range is smaller than only FM

A

FALSE: operational range is GREATER than only FM

33
Q

CF component of CF-FM bat calls permits more accurate determination of ______________________ and _________________________.

A

target velocity, fluttering movement

34
Q

Where do CF-FM bats normally hunt/forage?

A

denser foliage

35
Q

Draw the pulse and echo for when an insect’s wing moves toward the bat vs away from the bat? (i.e. what occurs to the frequency and amplitude of the echo)?

A
  • toward bat = higher frequency and amplitude echo
  • away from bat = lower frequency and amplitude echo

(slide 16; hint = doppler shift)

36
Q

Describe how echolocation works when bats glean their prey from leaves and twigs (or the ground).

A
  • hover and emit continuous FM calls
  • no terminal buzz
37
Q

TRUE or FALSE: when bats glean their prey from leaves and twigs (or the ground), there is no approach phase

A

FALSE: no terminal buzz phase

38
Q

How do bats produce echolocating calls?

A
  • generate motor pattern that is sent to the larynx
  • laryngeal muscles are ‘superfast’, allowing them to contract at an extremely high frequency (i.e. allow for TERMINAL BUZZ)
39
Q

TRUE or FALSE: some CF-FM bats have bizarre noses that can be used to direct and detect echolocating calls

A

TRUE

40
Q

Which features of echolocation can be shifted in different contexts?

A
  • call duration
  • intensity
  • frequency
41
Q

TRUE or FALSE: when there is more ambient noise, bats make their calls longer and more intense

A

FALSE: LESS intense

42
Q

Draw a diagram to show how bats’ echolocating calls are shifted in the presence of more and more ambient noise

A

slide 20; longer and less intense calls

43
Q

TRUE or FALSE: beam width is larger in the search and approach phase, and smaller in the terminal buzz phase

A

FALSE:
- larger in terminal buzz phase
- smaller in search and approach phase

44
Q

How do bats avoid getting confused by the echoes from other bats?

A
  • when foraging with other bats, FM bats adjust FREQUENCY and TEMPORAL features of their calls
  • this allows them to separate out the call features of one another
45
Q

TRUE or FALSE: the auditory system of the bat is very differnt from non-echolocating mamals

A

FALSE: very similar

46
Q

label slide 25

A

slide 25

47
Q

Bats move their ears between calls to enhance ____________ and _____________ differences between left and right

A

intensity and timing

48
Q

What does the TRAGUS of the external ear do?

A

direct echoes and enhance intensity and timing differences (for calculating azimuth and elevation)

49
Q

Why do FM bats contract the middle ear muscles during a call?

A

attenuates the loudness of their call so they are not deafened when echolocating

50
Q

TRUE or FALSE: bats have poor high-frequency hearing

A

FALSE: low-frequency

51
Q

Draw the threshold vs frequency graph comparing humans and horseshoe bats.

A

slide 29, graph A; horseshoe bat shift to right because they cannot detect low frequencies

52
Q

Which part of the ear is very large to account for a large hearing range in bats?

A

cochlea

53
Q

TRUE or FALSE: high frequency is encoded at the base of the cochlea (near outer ear); low frequency is encoded at the tip of the cochlea (near inner ear)

A

TRUE

54
Q

What part of the ear reflects hearing range?

A

basilar membrane

55
Q

TRUE or FALSE: in CF-FM bats, the FM frequency of echoes is expanded

A

FALSE: CF frequency expanded

56
Q

Why is the CF frequency of echoes expanded in CF-FM bats?

A

provides greater sensitivity to CF that assists in Doppler shift analysis

57
Q

Draw a diagram of the auditory pathway from the cochlear nuclei to the cortex

A

slide 35

58
Q

What frequency range is the largest reflected area in the inferior colliculus of a bat?

A

60-63 kHz

59
Q

TRUE or FALSE: specific neurons respond to specific calls

A

TRUE

60
Q

The inferior colliculus is not only tuned to frequency, but also highly sensitive to __________________________.

A

timing between calls and echoes

61
Q

TRUE or FALSE: inferior colliculus neurons have a very high threshold and therefore the timing of activity is responsive to even high amplitudes

A

FALSE: LOW threshold; responsive to even LOW amplitudes

62
Q

Draw a graph of biosonar signals in bats using frequency vs time.

A

slide 42

63
Q

TRUE or FALSE: difference between FM (FM-FM areas) encodes velocity, whereas difference in CF (CF-CF areas) encodes distance

A

FALSE:
- FM-FM = distance
- CF-CF = velocity

64
Q

TRUE or FALSE: cortical organization in FM bats also have the doppler and CF regions

A

FALSE: LACK the DCSF and CF regions

65
Q

____________ species have a bimodal distribution for over-representation of frequencies: one area for _________, a second for _________________.

A

gleaning; echoes; passive learning

66
Q

Draw the distribution of number of sites and best frequency in FM bats.

A

slide 45

ZOOL 342 (21 decks)

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