Alternative Indicators of Crowding at Alcatraz Island: A Comparative Analysis

The Sounds of Silence in Muir Woods

The Sounds of Silence in Muir WoodsProblem: impacts to soundscapes; impacts to wildlifeManagement Strategies: reduce the impact of useManagement Practices: zoning; information/ education

Muir Woods National MonumentOld growth redwood forestHuman-caused noise750,000 visits annually1908 (Teddy Roosevelt)John MuirEmergence of soundscapes and natural quietSpotted owls

The Sounds of Silence in Muir WoodsPeace and quietNPS policiesVisitor surveys37 decibels as standard of qualityDesignation of quiet zone in Cathedral GroveSound monitoringEquivalent of 30% reduction in visitor useStrong visitor supportThe Sounds of Silence in Muir Woods

Muir Woods National Monument

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The Sounds of Silence in Muir WoodsSocial Norm Curve for Sounds at Muir Woods

Inside NPSMUIR WOODS NATIONAL MONUMENTNew Signs Encourage Appreciation Of Natural Sound

Rather quietly, Muir Woods recently installed five new wayside signs that encourage visitors to walk quietly and enjoy the natural soundscape of the primeval forest.

Just minutes from the Golden Gate Bridge and a major metropolitan area, the ancient forest is in sharp contrast to the busyness of the surrounding modern world.

On a weekday, in the winter or spring, early in the morning or late in the afternoon, not on a holiday, and on just about any rainy day, visitors may enjoy a few moments of quiet in Muir Woods without intrusion from mechanical or human-made sounds. But, its becoming more challenging as the San Francisco Bay Areas population of seven million people continues to swell and will increase by millions over the next 50 years.

With fewer places to go without the sound of a blustery motorcycle or the rumbling airplane overhead or the constant drone of a nearby freeway, future generations will be hard-pressed to find a quiet place to listen to natural sounds for reasons of health, inspiration, and restoration. Not only does noise affect the human species, but the other species as well. Animals that depend on their sense of hearing for avoiding predators, finding mates or safe territories, finding food, and nurturing young, will be less fit to survive in urban areas.Inside NPSMUIR WOODS NATIONAL MONUMENTNew Signs Encourage Appreciation Of Natural Sound (continued)

The soundscape signs are a gentle reminder that Cathedral Grove is the parks quiet refuge for people and animals alike. The grove of mature trees, located further from the bustling parking lot and park entrance, has a history of reverence and quietude. Cathedral Grove is the site where delegates to the first United Nations in 1945 came to commemorate President Franklin Delano Roosevelt, the chief architect of the U.N.

Muir Woods offers evening programs to experience the natural sounds of an old-growth forest on a safe and leisurely walk. Though the forest and weather are less dramatic in the summer than in the winter, visitors can listen to the watery music of Redwood Creek, enjoy the forest fragrance on a still evening, and the gentle soughing of the wind through the canopy of giant trees. Contrary to what is generally observed by first-timers to Muir Woods, the forest is not silent, but quiet.

The Muir Woods soundscape signs were funded by the National Park Service Natural Sounds and Nights Skies Division. The project team includes Mia Monroe, Michael Faw, Gina Farr, Lou Sian, Tamara Williams, Karen Trevino, Erica Pilcher, and Bob Manning.Contact InformationName: Lou Sian, Park Ranger and Media SpecialistNew Signs Encourage Appreciation of Natural Sound (Inside NPS)Virtual Tour of Muir Woods (2:36)When Owls Attack! (0:57)The Sounds of Silence in Muir Woods05Dugan Nature SoundsMuir Woods Survey2005Nature Sounds41482.277eng - iTunNORM 00000043 0000003E 000003A5 000006F7 00000258 00005724 000022E6 000032D2 0000433E 00005724eng - iTunSMPB 00000000 00000210 0000070A 00000000001BE0E6 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0000000001Dugan Nature SoundsMuir Woods Survey2005Nature Sounds63841.934eng - iTunNORM 00000010 0000000C 000002D5 00000229 0000D282 00000CF5 00001E0A 000019D9 0000D268 0000D268eng - iTunSMPB 00000000 00000210 00000888 00000000002AEB68 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0000000002Dugan Nature SoundsMuir Woods Survey2005Nature Sounds46105.71eng - iTunNORM 00000009 00000006 00000209 00000130 0000A23E 0000030F 00001B09 00001400 00009492 00009492eng - iTunSMPB 00000000 00000210 00000833 00000000001EFC3D 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0000000003Dugan Nature SoundsMuir Woods Survey2005Nature Sounds45531.047eng - iTunNORM 0000000B 0000000A 000001B9 0000015F 0000A42F 0000A42F 00001901 00002173 00001BA7 00001BA7eng - iTunSMPB 00000000 00000210 00000909 00000000001E9867 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0000000004Dugan Nature SoundsMuir Woods Survey2005Nature Sounds45034.746eng - iTunNORM 0000002B 00000017 00000385 0000030B 00003D1F 000013E5 0000273F 0000425E 000013E5 000013E5eng - iTunSMPB 00000000 00000210 000007DE 00000000001E4412 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000Chart13.42.61.50.2-0.7-1.6-2.1-2.6-2.8-3

AcceptabilityGroup SizeAcceptability

Sheet1Group SizeAcceptability53.4102.6151.5200.225-0.730-1.635-2.140-2.645-2.850-3

Chart23.851.75-1.02-2.83-3.44

Acceptability

SPL Chart3.851.75-1.02-2.83-3.44

Sound Pressure Level (SPL)AcceptabilitySound Pressure Level Norm Curve

Noise Free Interval3.851.75-1.02-2.83-3.44

Noise Free IntervalAcceptabilityHuman Noise Free Interval (in seconds)

Percent Time audible (Nature)3.851.75-1.02-2.83-3.44

Percent of Time AudibleAcceptabilityPercent of Time Audible (Natural sounds)

Percent Time Audible (human)3.851.75-1.02-2.83-3.44

Percent of Time AudibleAcceptabilityPercent of Time Audible (human caused sound)

Human Caused Events3.851.75-1.02-2.83-3.44

Number of EventsAcceptabilityNumber of Human Caused Sound Events

Sheet2Sound Pressure Level (SPL)Human Noise Free Interval (In seconds)Percent of Time Natural Sounds AudiblePercent of Time Audible (human noise)Number of Human Caused Sound EventsRecording 13.8530.53.8533.53.851003.8503.8503.85Recording 21.7533.51.752.31.7597.81.7594.11.75101.75Recording 3-1.0238.5-1.021.3-1.0297-1.0296.5-1.0223-1.02Recording 4-2.8346-2.830.3-2.8352.1-2.8399.4-2.8322-2.83Recording 5-3.4448-3.440.5-3.4440.3-3.4498.6-3.4443-3.44

Sheet3