Acceptability and Motivation Norms of Human-caused Sounds

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

2. Soundscape • What is it? • human perception of sound resources Why is it important? • NPS mandated to protect soundscape • 1998 Nationwide Survey72% identified natural quiet as important for preserving parks (Haas & Wakefield, 1998)

3. Research Questions • How do visitor acceptability of sounds ANDconsensus regarding acceptability of sounds vary by: • the amount of human-caused sound? • level of motivation for a quiet setting?

4. 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

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

6. Previous Research • Studies in Muir Woods(Pilcher, Newman, Manning, 2008;Stack, Newman, Manning, in review) • Phases I & II - 2005Focused on identifying indicators & standards for soundscape • Phase III - 2006-2007 Studied feasibility and success of implementing strategies to manage sound

7. 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

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

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

10. Hypotheses • H1 - As the amount of human-caused sound increases, visitor acceptability of sound will decrease. • H2 – Consensus regarding acceptability of sound is greatest for the quietest and the loudest sounds. • H3 - As motivation for a quiet setting increases, visitor acceptability of human-caused sound decreases. • H4 - 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.

11. Study Location Muir Woods National Monument • Established in 1908 • 15 miles north of San Francisco • 700,000 visitors annually • Surveyed in Cathedral Grove

12. Dose-Response • Expose visitor to specific amount of noise (dose) & document reaction (response) RECORDING Very Annoying Very Pleasing

13. Motivation • K-means cluster analysis - divided into low, moderate, high motivation levels

14. 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.bThis is the mean for the second recording of the pair.

15. Very Pleasing Acceptability Acceptability of sound recordings Visitor Acceptability of Sound Recordings 75 % time above Neutral 0 60 30 90 100 Very Annoying % Time Above

16. 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. .

17. 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.

18. Very Pleasing Acceptability Low motivation Moderate motivation Effects of Motivation on Acceptability Neutral Very Annoying 0 60 30 90 100 % Time Above Highmotivation

19. Very Pleasing Acceptability Low motivation Moderate motivation Effects of Motivation on Acceptability 75-80% time above 80-85 % time above 75% time above Neutral Very Annoying 0 60 30 90 100 % Time Above High motivation

20. PCI Difference - Motivation Levels aPercentages 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.

21. Hypotheses Supported? • H1 - Human-caused noise , visitor acceptability • H2 - Consensus greatest at the extremes • H3 - Motivation , visitor acceptability • H4 - Motivation , consensus more likely to be greatest at extremes SUPPORTED SUPPORTED SUPPORTED SUPPORTED

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

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

24. ANY QUESTIONS? THANK YOU!