The 13-year periodical cicadas in the Midwest. In this recording I was lucky enough to have some forest birds also sing throughout the steady drone. Recording made with Marantz PMD661 (**with beefed up and extra quiet pre-amplifiers by Oade Brothers Electronics), running Samson CO-2 matched true stereo microphones. My original recording was made at the highest bit rate allowable on my machine -- 98khz.