BSCI401 Exam #1
If you wanted to record continuously for 24 hours, how much memory would you need if your recording device sampled at 44 kHz? Give two suggestions for how you could reduce memory requirements without losing the ability to capture a rare sound.
44,000 cycles/s *86,400 s= 3.8 * 10^9 cycles= 3,800,000,000 cycles= 3800 mB
Oilbirds produce clicks in damp caves and use the echoes to orient and avoid obstacles. If an oilbird has the same auditory sensitivity as a human, i.e. can hear sound above 0 dB, how far away could it detect an obstacle if the clicks register 78 dB 1 m from the bird?
6dB for every doubling of distance. 78/8=13 2^13=8192m
Some sound analysis systems can digitize sounds using 8 bit or 16 bit samples. Explain how these two recordings would differ in sound.
8 bit samples mean that the full amplitude range is divided into 2^8= 256 possible values, whereas 16 bit samples mean that the full amplitude range is divided into 2^16= 65,536 possible values. Therefore, 16 bit samples can gather 256 times more data than 8 bit samples, resulting in greater resolution of sound, less noise, and more accurately the digital recording captures the original sound.
Explain what aliasing means and indicate how it can be avoided when digitizing sound.
Aliasing= if you do not sample your sounds at a high enough rate, any frequency in the sounds that is higher than half the sampling rate is aliased meaning that you will see an artifact in the spectrogram consisting of an inverted version of what the sounds should have looked like if it had been sampled at a sufficiently high rate It can be avoided by sampling at a higher rate so that the sounds are not higher than half the sample rate use "tapered" cutting windows that turn the segment off and on slowly
Explain why a fish lying on the bottom of a pond is not likely to hear a fisherman walking along the bank , but is much more likely to hear him walking through the water.
Because of the difference in acoustic impedance between air and water. Acoustic impedance=speed of sound * density of medium, and water is more dense than air, and most of the energy of a sound produced in air by the fisherman will reflect off of the surface of the water.
Provide an operational definition of communication that could be used to develop testable hypotheses regarding how selection shapes signal form or information content.
Communication= when there is a sender and a receiver, and the sender intentionally produces a signal to convey information to the receiver. The signal must make it to the receiver visually, audibly, olfactory, electrically, or through touch, and must be transmitted efficiently through the certain medium (air, water, etc.) so that the receiver can process the information
Some bats are able to use the frequency of their emitted calls and the frequency of the returning echoes to tell if prey are moving toward or away from them. Provide an explanation for how they can do this.
Doppler shift: When the sound source is moving, the frequency of the sound will be altered. Approaching sounds are higher in frequency, and receding sounds are lower in frequency.
Explain in qualitative terms what Fourier analysis does
Fourier analysis is a method by which we can create or analyze animal sounds. It breaks down the sound's compound waveforms into homogenous segments and creates a frequency spectrum for each segment. These frequency spectrums are strung together in order to see how the frequency spectra changes as the sound progresses, forming a spectrogram.
Why do low frequency sounds tend to travel farther through the understory of a tropical forest than high frequency sound?
Frequency and wavelength are inversely proportional, so low frequency sounds have longer wavelengths. With that said, sounds with longer wavelengths are able to get around more obstacles (in the understory of a tropical forest) and therefore travel farther.
Many frogs and insects chirp, i.e. emit tones in a pulsatile manner. What should the power spectrum (amplitude vs frequency plot) look like for this type of vocalization?
It would show 3 lines of frequency spectrum, including the carrier f and the side bands at f-w and f+w, but the amplitude of the side bands don't exceed f amplitude
Which type of modulation, AM or FM, resists degradation better if transmitted through a forested environment?
Low AM
Assuming equal sound intensity at the source, which type of media will carry sound farther: air, water or land? Why?
Sound will travel the furthest on land>water>air. This is because the denser the medium is, the closer the molecules are together, and the easier it is for sound to move from one molecule to the next
What frequency of sound should a killer whale emit to insure that it receives an echo from a seal that is 1.5 m in length?
Speed of sound in water= 1500 m/s 1500 m/s/frequency= 1.5 m/s (wavelength=speed of sound/wavelength) Frequency= 1000 Hz
Define and discuss the difference between the near field and the far field
The near field is close to a sound source, and the molecules flow back and forth in unison. The far field is at distances about 1/3 of the wavelength of the sound, and sound travels as a wave away from the source. In the near field the molecular displacements are greater than the pressure differences, and in the far field the pressure displacement is greater than the molecular displacements. In the near field, ears detect particle movement, whereas ears detect pressure waves in the far field.
If you captured a male and female insect, how could you tell which sex was likely emitting a mate attraction pheromone and which was receiving it?
The sex that would be receiving the signal would have many more receptors or hair-like structures to be able to pick up the signal
1. Many animals emit contact calls to coordinate group movements. For these calls to be effective at communicating the range of an animal, what characteristics must they possess? How would you expect these features to differ if the animal was a dolphin versus a vervet monkey?
a. -Signal design parameters: bandwidth, frequency, duration, modulation type and rate, location of sender and receiver, transmission medium-Dolphins, live in water, sound energy propagates better, less attenuation of high frequency sounds-vervet monkeys, live on land, need to have lower frequency sounds so that they can propagate far enough to reach their clan
1. Summarize the similarities and differences between the eyes of a human and the eyes of an octopus.
a. -Similarities: Camera eye, lens, retina with photoreceptors, color vision, cones and rods-Differences: human eye has photoreceptors in the back of the retina, light must travel through bipolar cells and nerves first, essentially retinal layers are in reverse order, blind spot; octopus eyes have photoreceptors in the front, so nerves dont block, therefore no blind spot
1. If life was discovered to have evolved underwater on Mars, would you expect the organisms to be able to detect X-rays, infrared, or visible light? Why?
a. -Visible light because water is transparent to most of the visible light range except for long red wavelength. Being transparent means that the medium reradiates light at the same frequencies it absorbed.-Xrays have so much energy that it would destroy molecules and break chemical bonds, so the energy is too high to be absorbed by water-IR is absorbed by water
Will the Fourier analysis of a mixture of two tones, 1 kHz and 5 kHz, emitted for either 1 second or 1/100 of a second be different? How and why?
a. -different-bandwidth= 5 kHz - 1 kHz = 4 kHz-Bandwidth of a spectrogram resulting from Fourier analysis for one second will be 4 kHz, but for 1/100 second will be 4x100= 400 kHz-Bandwidth increases by a factor of 100 since time is 100 times faster
How does an enlarged throat sac influence frog vocalizations?
a. A frog's throat sac can act as an impedance matching device. The thin membrane of the sac and the contained air create a combination that has an acoustic impedance intermediate between ambient air and solid living tissues. If the throat is sufficiently inflated, it can produce a large radiating surface. b. Air is expelled from the lungs through the larynx, and into the throat sac. The vibration of the larynx emits a sound which resonates within the vocal sac. The resonance allows the sound to be amplified.
What is acoustic impedance and how does it affect signal production and reception?
a. Acoustic impedance= the degree to which a medium is compressible by sound pressure, and it dictates efficiency of sound production/reception by organisms. It depends on the density and speed of sound of that medium. Transmission between media with different impedances is difficult. b. Reflection=when the difference is large, most sound energy will undergo reflection at an equal and opposite angle c. Refraction=when the difference is small, some sound energy will cross boundary, but its direction of travel will change.
Why is the mammalian larynx thought not to be homologous (share common ancestry) with the avian syrinx?
a. Although they both function in sound production, they have different structures and locations.The larynx is located at the top of the trachea and contains hard membranes (vocal cords) whose vibration as air passes is controlled by a complex of muscles and cartilage. b. The syrinx is a body structure that lies at the low end of the trachea and is surrounded by an air sac. The syrinx becomes a resonating chamber in conjunction with highly elastic vibrating membranes.
1. Why would an animal that relies on heat perception have a more difficult time "seeing" than an animal that relies on visual light?
a. Animals that use IR to find prey do so because the prey are generally hotter than their environment b. This could be an issue if you're already in a hot environment or the prey hides behind something that doesn't have a heat signature
1. How do animals with pressure detector ears perceive frequency?
a. Based on frequency of the neuronal response rate. The rate at which the nerve cell fires in response to the mechanoreceptor movement when sound hits it determines the perceived frequency.
Male howler monkeys have a much larger throat than females. Explain why this difference is likely to influence the sounds they make.
a. Because male howler monkeys have a much larger throat than females, their voices are much louder and deeper. In their larger throat is an enlarged hollow hyoid that acts as a resonator that amplifies their sound.
1. Summarize the similarities and differences between the photoreceptors of a human and a honeybee.
a. Bees have compound eyes, mosaic image, no need to focus, poor sensitivity in low light, and are lightweight b. Humans have camera eyes, sharp & clear image, and need to focus light
1. Bioluminescence has evolved (or been acquired) independently in a variety of marine and terrestrial organisms. Provide an explanation for why it is not more widespread.
a. Bioluminescence occurs through a chemical reaction that produces light energy within an organism's body. For a reaction to occur, a species must contain luciferin, a molecule that, when it reacts with oxygen, produces light
1. Why is the sky blue during the day and red at sunset?
a. Blue during day because the molecules in the air scatter blue light from the sun more than they scatter red light b. Red at sunset because the blue light has been scattered out and away from the line of sight
1. If you were lost in the desert at night and had the ability to emit monochromatic light as an SOS signal, which color would you choose and why?
a. Blue/Green because the background at night is black and sand dunes look relatively orange b. In sand dunes the available light illumniation level= high (white), the background hue is orange, and the optimal signal color is blue-green
Explain how songbirds can produce two different sounds at the same time.
a. Branched syrinx: can independently control air flow coming from each side of the syrinx, their syrinx is below the branches so they can control both.
1. What is an otolith and how is it involved in fish hearing?
a. Calcium carbonate strutcure located in the inner ear that detects gravity, balance, and movement b. Endolymphatics infillings and they help fish detect low frequency sounds because particle motion causes movements of otoliths in ear chambers
1. Summarize the differences between a camera-type eye and a compound eye. Which has better resolution, and which has greater light sensitivity?
a. Camera eyes capture more detail , have better resolution, and compound eyes get a mosaic-type image and have greater light sensitivity
1. Why does a carrot look orange and blood looks red?
a. Carrots are orange because they absorb certain wavelengths of light more efficiently than others. Beta-carotene is the main pigment and is mainly absorbs in the 400-500nm region of the visible spectrum with a peak absorption at about 450nm i. Carotenoids absorb blue and green, reflect yellow and red b. Blood is red because of the hemoglobin inside our red blood cells. Hemoglobin is a protein that forms a complex with iron molecules and together they transport oxygen molecules throughout the body. Iron has the property of reflecting red light and because there is so much iron in our blood, blood looks red
1. Why do most plants appear green?
a. Chlorophyll absorbs deep blue and red light, and green is not absorbed, its reflected
1. What advantage is there to a fish which is dark on the back and light on the belly?
a. Countershadowing- To a predator, a fish with a light belly will be more difficult to see, because it will match the effects of sunlight entering the water from above. A dark back would camouflage from predators above because it will the darker hue of the ocean below
Explain how cricket wings are modified to produce sound that is loud only at a narrow range of frequencies.
a. Crickets use resonators (wing harp and mirror) to amplify their sound. Animals with high Q resonators can produce loud sounds but only at a narrow range frequency
Explain how katydids and some other insects produce ultrasound, i.e. frequencies over 20 kHz, when they are only able to move legs or wings back and forth 100 times/sec.
a. Crickets use stridulation (scraping a file over a plectrum). The max contraction rate is 100/s. Consequently, they use frequency multipliers (like teeth in a comb) to attain higher frequencies.
1. Explain what is meant by labeled-line coding and give advantages and disadvantages associated with it.
a. Each signal reaching the brain has a specific label associated with it-one signal means pain in lower back and another means hot on left foot b. Disadvantage= many receptors are to needed to convey a diversity of signals c. Advantage=processing is easier in central nervous system
How do fish produce sound?
a. Fish have a wide variety of sound-producing mechanisms. One way is to use muscles to vibrate their air-filled swim bladder (if that species has a swim bladder). Others may grind their pharyngeal teeth together or rub their pectoral fins on their sides, for example. b. Fish produce sounds by vibration of their swimbladder, which is a resonant monopole structures which expands and contracts around a central point and radiates sound symmetrically from source.
1. Describe what flehmen is and explain how it is used to determine reproductive state by an animal that you name.
a. Flehmen= conspicuous posture characterized by eversion of the upper lip that facilitates the transfer of nonvolatile urinary chemicals to the vomeronasal organ
1. Explain the process of fluorescence and provide an explanation for why it seems to be rarely used by animals.
a. Fluorescence is when greenish light is emitted in response to UV illumination b. UV is only effective in a dark environment
1. Large ships frequently travel between continents via shipping lanes, some of which involve canals, such as the Panama or Suez. Describe the potential consequences of frequent ship movement for communication underwater by aquatic animals, such as whales or fish, and if you think this could impact populations of rare or endangered species.
a. Frequent ship movements creates lots of noise underwater. As a result, animal communication which aren't as loud will go unheard. This inhibition of communication can be detrimental to animals trying to notify others of their location, call out the presence of predators. These animals will be forced to move away to environments which are more sound conducive than along areas of high travel. This can impact the make up of an ecosystem and negatively impact populations of endangered species who are displaces or rely on displaced organisms for survival.-boat traffic noise occurs at 1000-10000kHz, so marine mammals will call at lower frequency making it harder to gather food and find mates
If you conducted a Fourier analysis of an ultrasonic vocalization and measured frequencies at 60 kHz, 80 kHz, and 100 kHz each with decreasing amplitude, explain how you would interpret the production of these sounds. Use harmonic series, fundamental frequency and Dirichlet's rule in your answer.
a. Harmonic series= When spectrum components are integer multiples of some frequency w b. Fundamental series= fundamental frequency=w= 20kHz i. First harmonic= 40 kHz, second harmonic= 60 kHz, third harmonic= 80 kHz, fourth harmonic= 100 kHz c. Dirichlet's rule= The amplitude of successively higher harmonics tends to decrease in an exponential manner.
Provide examples of communication in which the receiver benefits and the sender a) benefits or b) suffers a cost as a consequence of sending a signal.
a. In honest communication. Example: Aposematic warning signal of the brightly colored poison dart frog -> the frog doesn't get eaten, and the predator doesn't get poisoned b. In eavesdropping. Example: Snakes listening for frog's mating calls to know when they are out and stationary (so that they can eat them)
If you want to reduce the error in your measurement of frequency, should you increase FFT window size or decrease FFT window size? Why?
a. Increase FFT window size because it gives you a larger sample size so that you can get a more accurate measurement
Explain four alternative mechanisms that can act to guarantee signal honesty
a. Index signals: signal production is constrained by physiology or body size b. Handicap signals: Signal production is condition dependent—costs of signaling can only be borne by some individuals c. Conventional/proximity signals: Honesty is enforced by punishing cheaters d. Absence of conflict of interest: Honesty is always favored, such as with close kin
1. How do insects with particle detector ears perceive frequency?
a. Insects have specialized nerve cells that act as mechanosensors (scolopedial cells)
1. Explain why the feathers of some birds appear black from one direction and red from another direction.
a. Iridescent feathers: color changes with angle of incidence due to refraction
1. If you did a chemical analysis by size and compound of a glandular secretion, how might you predict which component would likely function as a territorial marker versus a mate attraction scent?
a. Larger compound are better for marking territory since they can persist (contain more proteins and lipids) b. Smaller compounds are good for attracting mates since they are able to travel further
1. Stomatopods use 16 visual pigments while we use only three. What advantage(s) might there be for organisms that rely on relatively few, rather than many, visual pigments?
a. Less energy needed to process visual information
Why do men have deeper voices than women?
a. Men have longer and thicker vocal cords, making them vibrate more slowly when air flow through the larynx. b. Sound produced in larynx near pharynx , vocal cords pushed into airflow with laryngeal muscles
Tree crickets sing from inside holes chewed in leaves and mole crickets sing from inside tunnels in the ground. For each case, explain why.
a. Mole crickets create a "bulb" in the ground and the pathway acts as a funnel. This amplifies their calls. Tree crickets rub their wings together to create vibration. This vibration creates sound. However, when compressed and thinned air meet at the edges of the wings, the sound cancels out. This is known as acoustic short circuiting. The smaller the wings, the larger this effect and the less efficient the broadcast of sound becomes. Baffles are made to overcome this problem. The cricket puts its wings flat against the leaf structure and sings, so that the sound travels to the leaf edge before short circuiting.
1. What determines the active space of a pheromone?
a. Molecule size and medium type- the active space expands and contracts as the concentration diminishes. There is a maximum size of active space that is set by the detection threshold and amount of odorant released (independent of diffusion rate)
1. Do you think chemical signalling to attract a mate is more common among terrestrial animals or among aquatic animals? Justify your answer.
a. More common among terrestrial animals because diffusion is slow in water and you need to be close, sessile, or utilize the current. In air diffusion is faster and you don't have to be very close or not moving to pick it up
Explain what happens to sound amplitude when an animal calls near a smooth boundary, such as above calm water, as a function of sound frequency
a. Near boundary sound will reflect instead of refracting if the boundary medium is dense yields sound shadow
1. Can animals with one eye determine distance? How?
a. Not as well because they don't have the benefit of overlapping visual fields (binocular vision), which uses angle deviation of eyes from forward position
1. Why can octopus change color faster than a lizard, like a chameleon? Provide a reason why lizards don't change faster (or octopus don't change slower).
a. Octopus use a specific type of neural control which allows for very fast changes. Whereas lizards just have cells that contain melanin pigment that can move around the cell by cytoskeletal motion, which is alot slower
1. We have less than half as many olfactory receptor genes as most rodents. Explain what those proteins do and provide a functional explanation for why such a difference exists.
a. Olfactory receptors bind ligands that cause protein channels to open and allow movement of cations across the membrane b. Rodents rely more on sense of smell than humans c. We gain a visual function from our loss of olfactory function
1. Explain how particle detector and pressure detector ears perceive sound.
a. Particle detector: near field, uses long thin hairs in near field by insects dynamic range and frequency response, structures that detect air motion (hair cells), mechanoreceptor which causes the nerve cell to fire when it is moved, directionally specific b/c the direction the hair cells is moved codes for different responses, alternatively, have hair positions which will only respond when moved a particular way, hairs of different lengths are more pliable and can inform about the frequency of sound, receiver must be within one wavelength to hear b. Pressure detector: far field, thin membrane responds or is modified by pressure waves without the whole organism having to respond, nerve cell attached to membrane and fires when the membrane vibrates, other mechanisms involve amplifying the sound before it reaches the neural network, bigger the membrane the more sensitivity it has, can differentiate direction, uses sensory cell and membrane that detects pressure differences
1. Why does a pressure differential detector ear provide more directional information than a pressure detector ear?
a. Particle detectors can measure directionality, so pressure differential detector has these unlike the pressure detector ear
1. How does a photoreceptor cell detect light?
a. Phototransduction- the light sensitive cells in the retina that absorb light and convert it into an electrical signal that is passed to the brain through the optic nerve
1. Which type of color production, pigment or structure, is likely to provide a better indicator of an animal's ability to acquire food? Justify and provide an example.
a. Pigment is likely to provide a better indicator of an animals ability to acquire food. Pigments are molecules which selectively absorb photons of some wavelengths and transmit others. In many species, carotenoids are obtained from an individuals diet and are involved in immune competency. Thus, the intensity of coloration can indicate animal condition. (Ex=widowbirds and bishops)
1. Some insects can perceive polarized light. Explain why they are able to determine the location of the sun, and therefore time of day, on a cloudy day as long as there is a small patch of blue sky.
a. Polarized light indicates solar position, and the orientation of light shifts throughout time of day, animal also has to be able to dtermine time because it will be the same at dusk and dawn b. The polarization of light originating from an area of the sky covered by cloud (below termed 'cloud light') consists of two components. The first originates from the cloud itself. White light illuminating the cloud remains white but becomes partially linearly polarized after scattering on the cloud particles (ice crystals or water droplets). The second component is caused by the scattering of light within the air column between the cloud and the observer. This column emits blueish and linearly polarized light.
1. What is the difference between a pressure detector and pressure differential detector ear? Give examples of each.
a. Pressure detector ear uses far field (ex:mammals, moths), pressure differential uses near and far field (ex: frogs, birds)
How does obstacle size influence the transmission of sound when the wavelength is a) greater the the diameter of the object, b) about the same as the diameter of the object, c) less than the diameter of the object?
a. Rayleigh scattering= When the object is a lot smaller than the wavelength & the sound is scattered equally in all directions b. Diffractive/mie scattering= when the object is equal in size to the wavelength & there is both a reflected and diffracted wave c. Simple scattering= When the object is greater than the wavelength & there is a single reflected wave
1. What is the difference between red light and a) a laser and b) infrared light?
a. Red light occurs around 625-700nm b. A laser occurs from 180-400 nm c. Infrared light occurs from 10^3-10-6 nm
1. Give two similarities and two differences between an olfactory receptor cell and a photoreceptor cell.
a. Similarities: they respond to external stimuli and fire action potentials through afferents b. Differences: Chemical vs light, ligand binding vs pigment conformational change
1. What features of a camera eye can increase resolution? Why don't all birds have the visual acuity of an eagle?
a. Size of lens, number of photoreceptors, the birds have fewer photoreceptors than eagles
Give animal examples of four different sound producing mechanisms. In each case, explain how sound is generated.
a. Stridulation- scraping a file over a plectum. Ex: grasshopper b. Percussion on a substrate- hitting a body part on the surface of another object. Ex: woodpecker c. forced flow of medium through an orifice or past a thin membrane-vibration created with air flow over a membrane in a tube. ex: humans d. vibration of an appendage- striking body parts together. Ex: male ruddy duck drumming bill against water trapped in feathers and air-filled sac on breast
Explain why it is impossible to measure frequency and duration with certainty at the same time using Fourier analysis (or our ears).
a. The Uncertainty principle: any fourier analyzer needs several cycles of a signal to compute component frequencies—the more cycles of a stable frequency component that the analyzer can measure, the more accurate that measurement of the frequency b. Sound signals have a time-frequency tradeoff c. If the analyzer only has a short time to estimate frequencies, each component will appear as a wide band in the frequency spectrum (larger the spread of different types of frequencies) and if a longer duration is available, frequency components will be narrow.
1. Explain why a small insect cannot use time-delay to determine sound direction.
a. The distance between the two ears makes it so that there is a very small time delay between when sound hits one ear vs another—without the function of head width, sound hits both ears at virtually the same time
1. Diamonds have a higher refractive index than glass. If you could make glasses out of a diamond, would the lens need to be thicker or thinner than glass to produce the same effect?
a. The lens for the diamond needs to be thinner to prevent the diamond from bending it so much towards the normal b. Bigger refractive index=takes light more time to travel through it and the and the angle of the refracted wave from the normal is smaller
1. Why do people need glasses as they get older?
a. The lens inside their eyes becomes less flexible, so they cannot focus images
Explain how toothed whales, like killer whales, emit sounds that propagate directly in front of their heads, rather than in all directions.
a. They create sound by blowing air out of their blowhole and generate sound by vibrating membranes, phonic lip, that propagates through the melon or by bouncing it off an air sac and through the melon forward. b. melons are oil-filled acoustic lenses that act to focus emitted sounds by refraction
1. Explain how some animals are able to see UV light and provide an explanation for why this ability is not more widespread.
a. They have photoreceptors with pigments that are sensitive to higher frequencies in the EM spectrum
1. Why can vertebrates perceive a greater amplitude range than most invertebrates?
a. They have specialized cells that synapse with auditory nerves. The tectorial membrane provides amplification mechanisms
1. How do animals find the source of a pheromone?
a. They travel against the concentration gradient of the chemical signal
1. Why are soap bubbles colorful?
a. Thin layer interference- the light rays are reflected off the inner surface of the bubble travel further than the light rays that are reflected off the outer surface. So the colors come from the interference of light reflecting off of the inner and outer surface of the thin soap film. Different colors interfere constructively and destructively depending on the thickness of the film
1. Explain how humans are able to perceive color
a. Trichromatic color system- three different kinds of cones with different pigments sensitive to different wavelengths of light
1. Why is it difficult to discern fine details under low light as compared to under bright light?
a. Under bright light, rods are most active which detect color and fine detail. In dim lighting, cones are most sensitive and active which detect grayscale.
1. What is the vomeronasal organ and what is it used for?
a. Used to detect steroid hormones by drinking a females urine and then they are able to detect when the best time to mate with that female is
1. What effect does anthropogenic noise caused by vehicular traffic have on bird song? Explain the prediction and the evidence.
a. Vehicular traffic noise is loudest at less than 2 kHz. Thus, in order to avoid being masked, the urban birds sing at higher frequencies. They found this by looking at the difference in minimum frequency of calls in forest vs. in urban areas.
1. Some animals tend to display at dusk or dawn while others tend to display during the middle of the day. Predict how these displays are likely to be different with regard to the animal's coloration and movement. What differences would you expect if the animal was in the forest or in the savanna?
a. Visual acuity better in bright light situations, fine motions impossible to see at dusk and dawn
1. Explain what would happen to our hearing if the bones in the middle ear were removed and the oval window of the cochlea became the eardrum?
a. When sound waves are transmitted from the eardrum to the oval window, the middle ear is amplifying the sound waves before they move into the inner ear. The pressure of the sound waves on the oval window is 20x higher than on the eardrum. So without the eardrum, we wouldnt be able to hear quiet sounds as well.
1. Describe a situation in air and in water that would create a sound shadow and a sound channel (i.e. give four different situations).
a. Wind for sound channel, gradient creates channel, warm air to cool air (works for both water/air), for channel there needs to be two barriers, surface of water acts as boundary, temperature gradient traps sound underwater, warm water current below
1. Rank the following types of electromagnetic radiation from long to short wavelength and indicate which acts most like a wave or most like a particle: x-rays, microwaves, UV, infrared, violet, red, green.
a. Xrays<UV<violet<red<infrared<microwave b. Highest frequency (shortest wavelength), X-ray à particle c. Lowest frequency (longest wavelength), microwave à wave
1. If you dissected the ear of a mammal with poor high frequency hearing, like us, and compared it to a mammal with excellent high frequency hearing, like a bat, what differences would you expect to see in the cochlea?
a. You would expect to see a thicker basilar membrane for bats b. Proportionally larger cochlea in mammal with excellent high frequency hearing (more sensitive to sound)
How much greater is the sound pressure produced by an echolocating bat, which emits 100 dB calls at 1 m, than a sparrow, which produces 70 dB calls at 1 m?
a. dB=20 logP1/Pr where Pr = 1kHz Bat: 100=20 log (P1/1) -> 5=log(P1) -> 105=P1= 100,000 dB Sparrow: 70=20 log (P1/1) -> 3.5= log(P1) -> 103.5=P1=3,162.3 dB 100,000/3162.3= 31.62x greater
