Cetacean Research tabs Fostex FR-2 for underwater recording
When Joseph Olson, founder of Seattle’s Cetacean Research Technology (CRT), was recording the underwater sounds of Ganges River dolphins in 2003, he knew he was missing some significant sections of sound. “The portable digital recorder I was using at the time was excellent, but it rolls off sounds above 40 kHz,” he recalls. “In any other application that would be fine, but the sound spectrum of the dolphins goes much higher. So I started looking for alternatives.”A year later, Olson found the Fostex FR-2 portable digital recorder, which can capture frequencies up to 90 kHz with 24-bit, 192 kHz record quality in Broadcast Wave (BWF) file format, using CompactFlash media. “That makes a big difference when you’re trying to record high frequency whistles and echolocations,” he notes. “There’s no other portable recorder that can do that, so the FR-2 the only digital recorder I recommend for that application.”
Founded in 1194, Cetacean Research Technology is a private firm that provides integration expertise and underwater recording systems based around hydrophones that Olson himself designs and manufactures. In addition to academic researchers, Olson’s clients include NASA, the National Oceanic and Atmospheric Administration (NOAA), the Scripps Institution of Oceanography and National Geographic Television, as well as movie producers, environmental consultants, energy companies and a growing number of recreational enthusiasts.
It wasn’t until relatively recently that scientists realized how much underwater sound is produced above 40 kHz. “There are dozens of species who produce sounds in the ultrasonic range,” says Olson, “primarily dolphins, porpoises, sperm whales and killer whales, plus various fish species and invertebrates like the snapping shrimp. When I was recording the Ganges River dolphins, I could only get the very bottom range of their clicks, and no whistling at all. The FR-2 addresses that issue.”
Colleagues at the Interdisciplinary Center for Bioacoustics (CIBRA) in Pavia, Italy have tested the frequency response and noise floor of various digital recorders, confirming that the Fostex FR-2 has the best frequency response and lowest noise level of any of recorders tested. "I use the FR-2 myself and recommend it to every customer who needs to record sounds above 40kHz," says Olson.
A physicist by training, Olson is an experienced marine researcher as well, having served as president of the Puget Sound chapter of the American Cetacean Society. Olson even developed his own line of hydrophones (underwater microphones) based on piezoelectric technology, providing optimal frequency and sensitivity characteristics in a design that is both more rugged and notably lower in cost than typical ceramic hydrophones. “I consider most of my customers to be colleagues,” he says. “We all share the same passion and desire to advance the quality of research in the field.”
Most high-end recording systems that CRT develops and sells are based around the company’s Model C55 hydrophone, with several other models available. Typical deployment involves the placement of the hydrophone underwater, with its power source and the FR-2 recorder safely above the water, protected by a Pelican case or dry bag. The last piece of any serious system is analysis software to bring the captured audio into the range of human hearing. “When you record that high, you really need to see the sound on a spectrogram,” Olson explains. “The synaptic responses of these animals are ten times faster than ours, so we have to slow things down in order to detect all the nuances we have been missing.”
Joseph Olson intends to continue pursuing his passion for marine mammal research through Cetacean Research Technology. “It’s great to see the growth of interest in this area,” he enthuses. “With tools like the Fostex FR-2, I think we’ll be seeing some fascinating new research results in the area of ultrasonic communications. I’m very pleased to be a part of it.”
