This lab consists of two parts:
In part 1, you will conduct three mini-experiments to familiarize yourself with the synthetic sonar device.
In part 2, you will propose and test a hypothesis about how the bat Micronycteris microtis might discriminate empty leaves from leaves occupied by prey.
Required parts of the write-up for this lab are indicated with a ✍️ icon. Fill out the indicated parts of the accompanying worksheet. You can use the hard copy (paper version) or download a copy of the electronic version.
Micronycteris microtis lab worksheet
In this first part of the lab, you will perform three mini-research projects that familiarize you with the sonar device and its output. This familiarization will help you develop and test a hypothesis about prey finding in Micronycteris microtis in part 2 of the lab.
In this experiment, you will assess the angular detection range for an object. In other words, you will test by how many degrees you can turn the sonar device away from pointing straight at an object and still receive an echo from the object. For this exercise, we employ two stacked weighted tubes as the target. You can also use a single taller cardboard tube.
Place the tube(s) on a table and align the sonar device with the pole (point it straight at the pole) at a distance of 1 to 2 meters. You can tape one end of the supplied fish wire to the poles (see images below). This allows you to keep the distance to the tube(s) constant as you rotate the device. This might be easier using the weighted tubes. See below for pictures of the setup.
Collect echoes from the tube(s). For each measurement, determine whether you can still discern an echo returned by the tube(s) (see example data below). Find the largest angle you can rotate the device left or right and still see an echo from the tube(s).
Mini experiment 1: Pictures of the setup
Mini experiment 1: Example data
<aside> ✍️ Write down (roughly) the maximum angles under which the sonar device can detect the tube.
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In this experiment, you will assess the spatial resolution of the device. You will test how far two objects must be separated before the device can detect a separate echo from both objects.
Place the cardboard tube, and the lab stand on the table, as shown in the image below. Place the cardboard tube at the table's farther edge, and the lab stand at the closer edge. Instead of a cardboard tube, you can also use two stacked weighted tubes.
At the largest separation distance between the tube(s) and the lab stand, you should see a separate echo from the lab stand and the tube(s). Next, move the tube(s) closer to the lab stand until you can no longer see a separate echo from the two objects (see example data below). Write down this distance and a hypothesis or explanation for why the echoes from the objects are no longer separable at this distance.
Mini experiment 2: pictures of the setup
Mini experiment 2: Example data
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Required hand-in for this mini-experiment: (1)Write down the minimal distance between the pole and the lab stand that still results in separable echoes. This distance will depend on what you consider separable and will be a judgment call to a certain extent. (2) Also, write down a short (1-2 sentences) explanation about why the echoes fuse into one for very short separations.
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