Graduation Year

2014

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Geography, Environment and Planning

Major Professor

Joni Downs

Keywords

avian monitoring, bioacoustics, conservation planning, localization, microphone array, urban ecology

Abstract

Bioacoustics is a relatively new field of research focused on studying the acoustic signals of vocal animal species. The field has been a topic of interest for many years due its passive approach and avoidance of species-level limitations, such as tracking rare or nocturnal species. It has been used to locate birds in terrestrial environments; however, localization in urban environments remains unstudied. This research aims to fill the gap by attempting to estimate the location of 30 discrete calls in eight unique, urban environments. Sites represented two distinct traffic scenarios: moderate traffic and high traffic. Three system arrays of three different sizes utilizing the Song Meter SM2+ units were tested at each site to determine the effect of array size on call visibility and location estimation. An American robin (Turdus migratorius) distress call was played through a loudspeaker at the thirty locations for each array. The spectrogram of each of these calls was examined to determine the number of channels with a visible call signature. If the file contained at least one visible call per song meter (36% of our sound files), cross correlation was used to determine the differences in the time of arrival of calls at all the microphones in the array, called lag values, which were used to calculate the origin location of the call. However, resulting lag values in this study were too large to produce reliable location estimates. This was likely due to imprecise synchronization in the field or poorly defined calls within the spectrograms. Our overall low visibility is likely a result of the high signal to noise ratio common in urban environments. Further research is necessary to continue to test the viability of acoustic localization in urban environments.

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