What’s that sound?

Scientists tune in to audio research

Elk, owls, coyotes, and snowmobiles all have been heard on Colorado State University campus lately. The sounds are coming from a listening laboratory where a research project between CSU and the National Park Service (NPS)  is analyzing acoustic data recordings to inform and improve management of national parks across the country.

Cecilia White trains a student to distinguish sounds in park audio recordings.

“Sounds, or the lack of them, play a significant role in visitor experiences and wildlife behavior in parks,” said Cecilia White, a research associate for the project. “Acoustic research is a growing field in natural resources sciences and has a variety of important applications from conservation to tourism.”

CSU is collaborating with the NPS Natural Sounds and Night Skies Division (NSNSD) to study detailed park audio recordings that provide valuable clues to wildlife and human park activity and their interaction. The audio data is collected through recording systems that are installed by NSNSD in selected parks for about a month at a time. The systems record audio (as mp3 files) and sound pressure levels (in decibels) and are designed to replicate the experience of a person on the ground.

NSNSD is part of the Natural Resource Stewardship & Science Directorate of the NPS and uses science, engineering, and technology to understand, restore, maintain, and protect acoustical environments and naturally dark skies throughout the National Park System. CSU researchers currently involved with the program are Ken Wilson, George Wittemyer, and Kevin Crooks with the Department of Fish, Wildlife, and Conservation Biology, and Lisa Angeloni with the Department of Biology.

Engaging students in acoustic science

Audio recording of sparring elk.

In 2013, the CSU project team created a program to give students the opportunity to gain acoustic

research experience.  The students are trained to distinguish different sounds and recognize how they appear on a spectrogram. Once they have tuned their senses, the students listen to recordings from the parks and identify the sounds they hear, such as animals, people, planes, or cars.  They use software designed by NPS to compile the percentage of time a sound was heard, the volume of the sound, and the frequency of the sound.
“This research opportunity taught me the importance of natural soundscapes and how human noises can have a significant impact on environments,” says Samantha Bietsch, a CSU junior majoring in fish, wildlife, and conservation biology. “Now when I am outside, I can distinguish all kinds of noises and identify where they are coming from.  My favorite part of the job was getting to hear the birds wake up in the mornings and hearing the coyotes howl.”

The listening lab just hired seven new student researchers and has employed a total of 18 students since its inception.

The sound of success

Grand Canyon National Park – Photo credit: Moyan Brenn/Flickr.

Acoustic research findings have already been incorporated into management policies. In Yellowstone National Park, the NSNSD documented where, how often, and how loud noise would occur under different management scenarios. Incorporating these data into its winter-use plan allowed Yellowstone to provide recreation benefits to oversnow vehicle users while protecting other visitors and wildlife from noise.

NSNSD acoustical data are also being used by Grand Canyon National Park to help manage air tours and protect visitors and park resources from the effects of aircraft noise.

The Division also projected noise level increases from a proposed highway expansion near Vicksburg National Military Park in Mississippi. In Glacier National Park, the NSNSD is studying grassland birds and how they are impacted by traffic noise.