As part of the Grand Canyon Soundscape program, park scientists currently deploy specialized acoustic monitoring equipment on the rim and inner corridor of the canyon for overflight and bioacoustic monitoring.

The acoustic data that is collected in the field is analyzed in custom software that produces spectrograms, or visual representations of the audio. These spectrograms visualize the sound pressure level in decibels (dB) and the frequency of noise events in particular areas. In the spectrogram below, time runs from left to right, the sound pitch (frequency) runs from bottom (low tones) to top (high tones), and the color indicates the volume (yellow and white are loud and blue is quiet).

Scientists use these data to measure how well we are meeting our objectives of preserving natural sounds.

The figure below is an example of how these acoustic measurements can be displayed. It shows the day vs. night sound pressure level for the summer of 2017 at one of our monitoring sites (GRCA031) on the South Rim.

The graph shows the noise level on the y-axis on the left and the pitch (frequency) on the x-axis on the bottom. The threshold of human hearing is indicated by the shaded area.

Daytime sound levels are represented in yellow and nighttime sound levels are represented in pink. The graphs shows that there are significantly higher sound levels during the day due to anthropogenic noise. Additionally, there is a significant jump in nighttime high-frequency sounds around the 3kHz mark; this is due to insects and the dawn chorus of song birds.

The natural soundscape is a fundamental resource of GRCA. The National Park Service has begun implementing low noise policies to protect the natural soundscapes in our parks. The Park Service is also pioneering quiet technology, such as quiet pavement that reduces vehicle noise from roadways.

The GRCA Soundscape program encourages visitors to think about ways they can help conserve natural quiet, including hiking with headphones rather than speakers, silencing cell phones, and keeping voices low. It is important all of us to do our part to protect the natural soundscapes of our parks. By doing so, we help ensure present and future generations can enjoy sounds like the dawn chorus or the rush of a waterfall, just without all the noise.

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