Communication and Signals III Flashcards
What is an important realization when thinking about signal communication systems?
Signals must be detected by the receiver, so they have to have sensory systems that allow this.
What are the two important properties of the human vocal signals? What do they represent in the human sensory system?
- Amplitude modulation (beating) and frequency
- AM => amplitude envelope, freq. => fine structure
What are the two functions of the auditory filter?
- Distinguish frequency
- process amplitude modulation
What is the basilar membrane? What is the major quality of basilar membrane? Where do high and low frequencies fall on the basilar membrane?
- Liquid moves cilia to produce an auditory signal. The basilar membrane is the base where the hairs are located (different areas are stimulated when sound travels into the ear).
- The basilar membrane is asymmetric (short and thick @ tympanum and thin/wide after the tympanum)
- High -> more inside the ear, low -> more outside the ear
What is the auditory filter? Under what scenario do you hear a two-tone chord?
- The size of the part of the membrane that vibrates.
- Two tones stimulate different auditory filters = two tones. When the auditory filters overlap, you cannot resolve the two different tones (wobble)
What is the wobble called when you cannot distinguish between two tones (auditory filter overlap)?
Amplitude modulation at a rate equal to the difference in frequency between the two tones
What are the two different kinds of filters you can have? What is the difference between them? What implications are there to having two different filters?
Narrow - better resolution of frequencies
Broad - better resolution of AM and of rapid frequency modulation (temporal information)
- You cannot be good at both AM and frequency resolution at the same time.
What are the two habitats that species can live in that distinguish between narrow and board filters? What are the implications of these?
- Open habitats - broad filters - trill of melody because AM allows for lots of information to be in a song
- Closed habitats - narrow filters - tonal songs b/c song can bounce of trees and get distort the sound of moving songs (think number of chirps instead of the melody)
What is an example of where having a narrow/broad filter matters and is seen in one species? What is another way it can change? How does this impact male success?
- Individual chickadees can vary in the width of their filters (so some are good at frequency resolution and others are good at AM (temporal resolution))
- Another way it can change is within one individual female (narrow in spring, broad in fall (high estrogen = better hearing))
- Male success is not dependent so much on the male’s call, but rather it depends on how the female interprets that call (whether she’s better at narrow/broad stuff at one time).
What example demonstrates that female hearing has an impact on mate choice? Elaborate. What were the results?
- Brown-headed cowbirds - male has a bimodal signal (song and dance) that female bends and exposes herself if she likes it.
- Researchers found that females with good frequency resolution (narrow) preferred longer songs (long tone). Females with good temporal resolution (AM) preferred shorter songs (jumping melody)
What is a flicker fusion rate? What is another example of how AM and Frequency resolution impact mate choice (Hint: vision)?
- FFR - threshold rate of light pulses at which the source seems to pulse vs shine continuously
- Yellow finches - Low rate = moving objects blur, prefer high intensity dances (poor temporal resolution). High rate = can track moving object better, prefer low intensity dance (high temporal resolution)
