Acceptability and Motivation Norms of Human-caused Sounds Muir Woods National Monument Lelaina D. Marin April 2009 Muir Woods National Monument Lelaina D. Marin April 2009

Soundscape Why is it important? NPS mandated to protect soundscape 1998 Nationwide Survey 72% identified natural quiet as important for preserving parks (Haas & Wakefield, 1998) What is it? human perception of sound resources

Research Questions How do visitor acceptability of sounds AND consensus regarding acceptability of sounds vary by:  the amount of human-caused sound?  level of motivation for a quiet setting?

Previous Research Effects of aircraft noise  Non-acoustical factors that influence annoyance  Motives strongly related to visitor evaluations of noise Physiological & psychological effects of noise  Stress, mild depression  Blood pressure & heart rate increase  Psychological effects even more pronounced in natural settings

Previous Research Effects of noise in outdoor settings  Urban residents may find natural ambient sound uncomfortable  Appropriateness of sound depends on visitor’s expectations

Previous Research Studies in Muir Woods (Pilcher, Newman, Manning, 2008; Stack, Newman, Manning, in review)  Phases I & II Focused on identifying indicators & standards for soundscape  Phase III Studied feasibility and success of implementing strategies to manage sound

Structural Norm Approach Norms - standards individuals or groups use to evaluate behavior  Personal vs. social norms Prior experience & knowledge of resource factor into individual norms Social norms aid in establishing standards Need to consider social norm curve

Social Norm Curve Minimal acceptable condition Optimal or preferred condition Range of acceptable conditions Norm intensity Standard # of encounters Acceptability

Motivation Psychological mechanism governing direction, intensity & persistence of behavior Searching for optimal level Intrinsic vs. extrinsic motives Recreation Opportunity Spectrum (ROS)

Hypotheses H 1 - As the amount of human-caused sound increases, visitor acceptability of sound will decrease. H 2 – Consensus regarding acceptability of sound is greatest for the quietest and the loudest sounds. H 3 - As motivation for a quiet setting increases, visitor acceptability of human-caused sound decreases. H 4 - As motivation for a quiet setting increases, consensus regarding acceptability of sound is more likely to be greatest for the quietest and the loudest sounds.

Study Location Muir Woods National Monument Established in miles north of San Francisco 700,000 visitors annually Surveyed in Cathedral Grove

Dose-Response Expose visitor to specific amount of noise (dose) & document reaction (response) Recording 1All natural sounds Recording 230% time above Recording 360% time above Recording 490% time above Recording 5100 % time above RECORDING Very Annoying Very Pleasing

Motivation K-means cluster analysis - divided into low, moderate, high motivation levels 1.Visitors have different reasons for visiting Muir Woods. Please rate the importance of each of the following reasons for your visit to Muir Woods today. Not at all important Somewhat important Moderately Important Extremely Important Experiencing solitude1234 Enjoying peace and quiet1234 Hearing the sounds of nature1234

Mean Ratings - Recordings 1 Percentages refer to the percent of time that human-caused noise is louder than natural sounds. a This is the mean for the first recording of the pair. b This is the mean for the second recording of the pair.

Visitor Acceptability of Sound Recordings Very Pleasing Acceptability Acceptability of sound recordings % Time Above Very Annoying Neutral 75 % time above

PCI Difference - Recordings a Percentages refer to the percent of time that human-caused noise is louder than natural sounds. 1 PCI a = first PCI value of the comparison. 2 PCI b = second PCI value of the comparison. * PCIs difference tests larger than 1.96 are significant at p <.05..

Mean Ratings - Motivation Level 1 Means with different letter superscripts are significant at the p <.05 level, accounting for multiple tests using LSD. † Percentages refer to the percent of time that human-caused noise is louder than natural sounds in each recording. * p<.05. ** p<.001.

Effects of Motivation on Acceptability Very Pleasing Acceptability Low motivation Moderate motivation High motivation Very Annoying Neutral % Time Above

Effects of Motivation on Acceptability Very Pleasing Acceptability High motivation Very Annoying Neutral % time above 75% time above 75-80% time above Low motivation Moderate motivation % Time Above

PCI Difference - Motivation Levels a Percentages refer to the percent of time that human-caused noise is louder than natural sounds in each recording. 1 PCI a = first PCI value of the comparison. 2 PCI b = second PCI value of the comparison. * PCIs difference tests larger than 1.96 are significant at p <.05.

Hypotheses Supported? H 1 - Human-caused noise, visitor acceptability H 2 - Consensus greatest at the extremes H 3 - Motivation, visitor acceptability H 4 - Motivation, consensus more likely to be greatest at extremes SUPPORTED

Management Implications Use standards to compare with current conditions ROS - zone for different sound experiences Need to consider loudness and sound source

Limitations/Future Research Controlling for sound level Order of recordings Nature of the study location Other possible research locations Demographic considerations

THANK YOU! ANY QUESTIONS?