This page last updated January 14, 2006
For my undergraduate degree, I attended Carleton College in Northfield, Minnesota, earning a B.A. in Biology in 1992. During that time I took a variety of courses, but my favorite courses focused on animal behavior and communication. I had the opportunity to work with Dr. Sylvia Halkin (now at Central Connecticut State University) studying singing behavior in male Northern Cardinals (Cardinalis cardinalis). We were trying to determine if a male with a larger repertoire might be more successful at maintaining a territory or attracting a mate.
When I got to Ohio State in 1994, I joined Dr. Mitch Masters in the OSU Batlab in the department of Zoology (now called the Department of Evolution, Ecology, and Organismal Biology). During my time in the lab I studied echolocation in Eptesicus fuscus, the big brown bat (which really isn't all that big). Echolocation is a system of biological sonar, where a bat emits a loud sound (symbolized by the orange curves in the figure below). The sound travels through the environment until it hits an object (e.g., a prey item like the insect shown here). The sound is reflected back towards the bat as echoes (symbolized by the gray curves in the figure). Since the speed of sound is relatively constant, the time between the production of the sound and the arrival of the echo tells the bat how far away the echo sources is. It's also likely that the echo will sound "different" because the sound is changed when it is reflected, so bats can also get some information about the physical structure of the echo source from the way the echo sounds when it arrives.
Research in Dr. Master's lab focuses on the echolocation behavior of the bats - how they change the sounds they produce in response to their environment how the bats use the information in the echoes returning from the target to dodge obstacles and capture prey. We also did a number of studies analyzing the characteristics of the echolocation calls and correlating the variation in those characteristics to the animals (such as their age or sex). Now that I'm out on my own, I'm still interested in studying the variability in bat echolocation calls. I have been working on trying to get recordings of bats from various parts of Georgia and the southeastern US so that I can build up a database of calls for these analyses. I am also continuing to modify the software for analyzing bat echolocation calls to refine the analyses so that we can learn more about bat echolocation.
I am most interested in seeing how bats use their echolocation signals when they are flying in the wild, so I had to develop a system for recording and analyzing the calls bats make in the field. Using a combination of different equipment, I assembled the following system while I was at OSU.
This system uses a laptop computer, a PCMCIA D/A converter card (the PCM-DAS16/330 from Measurement Computing), a U30 bat detector (from UltraSound Advice) for a microphone, and recording software called CBDISK (from Engineering Design). This system has the benefit of being portable, while still recording at 333 kHz sample rates, making it possible to record sounds that go well over the range of human hearing.
The recordings made by CBDISK are quite large (about 200 megabytes for 5 minutes) and often contain thousands of calls. To minimize the time required to actually analyze those sounds (and to minimize the amount of direct input required) I have used a variety of software programs to automatically extract and analyze the calls recorded using CBDISK. I have also written programs to convert the inaudible sounds produced by the bats into a form that humans can hear (similar to the technique used by many bat detectors). Click here for a sample of a recording that has been made audible like this (the sound requires RealPlayer to play).
The extraction process takes several steps, summarized in this flowchart:
|
|
|
If you want to learn more about my research, click the link below for more information:
 | How do you catch a bat to record in the first place? |
