Question

Show all your work. Indicate clearly the methods you use, because you will be scored on the correctness of your methods as well as on the accuracy and completeness of your results and explanations.

To prevent deer from running across highways, researchers are investigating sound-emitting devices that would frighten deer before they reach the highway. As part of the investigation, the researchers set up  20 devices along a two-mile stretch of road. When a deer approached a device, the device would activate and emit a sound. The researchers recorded whether the deer moved toward the highway (positive response), away from the highway (negative response), or did not move (neutral response).

The researchers kept the loudness of the sound constant at  60 decibels. However, they varied the pitch of the sound. There were  6 treatment levels, all measured in kilohertz  (kHz): 0,  0.28,  1,  8,  15, and  28. The order of the treatments was randomly assigned.

(a) The control in the experiment was  0 kHz, or no sound. What information is gained by using the control with no sound that could not be obtained if no control were used?

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Question 2

(b)(i) What is one advantage to keeping the loudness at a constant  60 decibels for all treatments?

(b)(ii) What is one disadvantage to keeping the loudness at a constant  60 decibels for all treatments?

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Question 3

(c) The results of the experiment are shown in the following bar chart.

Based on the results, would you recommend using a sound-emitting device to keep deer from running across highways? Explain your answer.

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Answer 1

The experiment involved setting up sound-emitting devices at the perimeter to avoid deer from crossing the highway.

The experiment was performed at a constant loudness of 60 decibels but the frequency of the sound was varied. In each of the scenarios, the response of the deer was measured as positive, negative, or neutral response.

a) There was a scenario of 0kHz frequency sound, which basically meant no sound. This acted as the control for the experiment. This was essential to ensure that the instrument itself did not affect any measurement. If it was the instrument that was driving the behavior of deers, then the pattern observed in other frequency intervals would be simply due to the presence of the instrument and not due to any sound. Also, when the response in other frequency cases is normalized with the responses in 0Hz frequency scenario, the basal behavior of deer in response to approaching a highway can be gotten rid of.

b) The advantage of having a constant 60 decibels across all frequency measurements is that the results will be purely based on the frequency of the noise and will not have any effect due to the intensity of the sound.

The disadvantage, however, is that any effect that might have been obtained by a different loudness will be completely missed.

c) You have not provided the graph for this part.