Lecture 5- Signaling and constraints

Question 1

Communication

Answer 1

Information exchange (response not necessary)

Question 2

Cue

Answer 2

Not intended

ex)
CO2 as cue for mosquitos to find mammals

Question 3

Signal

Answer 3

Intended

Evolved because of their effect on others

Question 4

Chemical signal

Answer 4

Large range

Can easily pass obstacles

Medium locatability

Low rate of change

Low production cost

Question 5

Auditory signal

Answer 5

Large range

Can easily pass obstacles

Medium locatability

High rate of change

Medium production cost

Question 6

Visual signal

Answer 6

Medium range

Can’t pass obstacles

High locatability

Medium rate of change

Medium production cost

Question 7

Tactile signal

Answer 7

Small range

Can’t pass obstacles

High locatability

High rate of change

Low production cost

Question 8

Evolution of acoustic communication across tetrapods

Answer 8

• Evolved repeatedly across tetrapods
• Associated with nocturnal activity

Question 9

Sound

Answer 9

Noise (stochastic process) or signal

Question 10

Fundamental frequency

Answer 10

Lowest frequency of the call

Question 11

Harmonics (H)

Answer 11

Multiples of the fundamental frequency

Question 12

Sender’s constraints:

Answer 12

Vocal apparatus and brain control

Question 13

F0

Answer 13

Lowest frequency of a sound

Question 14

Formants (F1-F4)

Answer 14

Concentration of acoustic energy around a particular frequency

Question 15

Mammals: F0

Answer 15

There is a correlation between body mass and the F0 (lowest frequency of a sound) across mammalian species.

• But some species have evolved specialized vocal folds or alternative voice production mechanisms to deviate. (ex) koala, deer, horse)

Question 16

Mammals: Formants

Answer 16

There is a negative correlation between body mass and formant frequency spacing across 16 mammalian species

Question 17

Vocal learners

Answer 17

Birds:
- songbirds
- parrots
- hummingbirds

Non-primate mammals:
- sea lions
- cetaceans
- bats
- elephants

Humans

Question 18

Receiver’s constraints

Answer 18

Variation in the frequency thresholds for different species

Negative correlation with head size and the highest audible frequency.

Animals with echolocators have small head size and high audible frequency

Question 19

Physical, physiological and cognitive restraints (sender and receiver): summary

Answer 19

• vocal production
• brain control
• hearing range
• discriminability and memorability

Question 20

Environmental constraints: Sound degradation

Answer 20

Attenuation (dB)

Noise (masking)

Blurring/distortion

Elongation

Eavesdropping

Question 21

Attenuation (dB)

Answer 21

Spreading loss (6 dB) + excess attenuation (reflection, refraction, diffraction, atmospheric absorption, scattering)

Question 22

Noise (masking)

Answer 22

Ambiant noise, transient noise (heterospecifics and conspecifics)

Question 23

Blurring/distortion

Answer 23

Reflection, atmospheric turbulence, selective frequency filtering

Question 24

Elongation

Answer 24

Echoes and reverberation

Question 25

Eavesdropping

Answer 25

Predator, audience

Question 26

Close/long range communication

Answer 26

- Timing of sounds production - Amplitude - High/low frequency sounds (range and ability to go past obstacles) --> low frequency sounds travel further - Wide/narrow frequency range (locatability) --> Wider frequency range improves locatability

Question 27

'Mobbing and distress' alarm calls

Answer 27

Low-frequency, broadband --> easy to localize, travel far

Question 28

'Flee' alarm calls

Answer 28

High-frequency, tonal, short duration --> not easy to locate, do not travel far