Motivation and Acceptability Norms of Human-Caused Sound in Muir Woods National Monument

Abstract

Acceptability of sound, natural or human-caused, was predicted to vary by an individual's motivation for quiet at Muir Woods National Monument. This study used a dose-response methodology where visitors (n = 157; response rate = 54%) listened to five audio recordings varying in the percentage of time that human-caused sound was louder than natural sound (percent time above). Visitors then rated the acceptability (pleasing to annoying) of each recording. Cluster analysis was used to segment individuals into three homogenous groups based on their motivations (i.e., low, moderate, and high motivation for quiet) for visiting the park. Results indicated that as percent time above natural sound increased, visitor ratings of human-caused sound decreased. Reactions to human-caused sound also decreased as motivation for quiet increased. Consensus regarding the acceptability of sound was greatest when the percent time above natural sound was lowest (i.e., quietest sounds). Recommendations are offered for setting standards to meet soundscape objectives.

Keywords:

• soundscape
• norms
• motivation
• Muir Woods National Monument

Acknowledgments

We would like to thank the staff at Muir Woods National Monument who provided help in organizing and planning the effort as well as offering volunteers and staff to aid in conducting the survey. Dan Dugan, Nature Sounds Society, recorded sounds in the park and prepared the original audio recordings. Kurt Fristrup, an acoustic specialist with the NPS Natural Sounds Program was responsible for manipulating the original recordings and providing us with the final version of the recordings that were used in this survey.

Notes

A description of PCI₂, as well as programs for calculating, graphing and comparing two PCI values can be found at http://welcome.warnercnr.colostate.edu/~jerryv

¹The recordings did not control for decibel level.

¹Cell entries are mean scores coded on a 4-point scale from 1 “not at all important” to 4 “extremely important.” Means with different superscripts across each row are significantly different at p < .05 using LSD post-hoc tests.

¹Motivation refers to how important a quiet experience is to the visitor. Low motivation = quiet experience not very important; Moderate motivation = quiet experience somewhat important; High motivation = quiet experience very important. Responses ratings were coded on a 9-point scale ranging from −4 (very annoying) to +4 (very pleasing).

²Percentages refer to the percent of time that human-caused sound is louder than (or above) natural sound in each recording.