Soundscape, Labor Day weekend, Artist in Residence, and Tall Thistle

On Sept 14 with the assistance of fellow SCA intern Molly Watters, I set up the soundscape equipment again. This time at a site much further from the road; I will be interested in seeing what the difference are. I thought I would share some pictures of the actual equipment and the set up process. 

Fellow SCA Molly Watters assisting me with setting up
the Soundscape equipment

The whole soundscape set up

 On Labor Day weekend the monument hosted a living homesteaders reunion and living history extravaganza. The monument had many programs running throughout the weekend, including living history activities such as pioneer toys, hand sewing, butter churning and many others. One of the programs was given by Ken Deardorff, who is the last person to receive land under the Homestead Act. There was also a discussion panel including 3 other living homesteader. It was a great opportunity to hear their  first hand stories of homesteading in Alaska.

Ken Deardorff- The Last Homesteader

Historian Blake Bell

Living Homesteader Panel

I was lucky enough to share living quarters with Artist in Residence Emily Melhorn. Emily is a writer living in LA and originally from Gettysburg PA. She did two programs while she was here, one about the American Dream and the other about Squatter's Rights. Emily was at Homestead for two weeks and during that time I was able to enjoy all of the bits of information that she gathered while doing research for her programs.

Artist in Residence- Emily Melhorn

I have also had a chance to write about the Tall Thistle for Homestead National Monument's NPS web page, you can read it here: http://www.nps.gov/home/naturescience/tall-thistle.htm

More on Soundscape

Basically the efforts of the listening center results in a few different graphics once I run the data through the 'R' program. I find that the bar graph is the most understandable. The listening center, I analyze 8 days for every site, and each day is split into 10 seconds for every 2 minutes. This comes down to 2 hours worth of data that I listen to. Every sound I hear has a code that I enter, like 2.4 is a truck, 9.1 is a domestic dog or 23 for thunder. When I run the results through the AMT program I can chose any code that I want highlighted on the graph. Right now I have run the program to highlight all vehicle sounds as compared to all audible noises. The nice thing about the resulting graph is that is is easy to compare different seasons at one site or to compare the same seasons at the same site. The graphs that I have included are for the same site but at different seasons. You can see that traffic is audible for a higher percentage of time than in the summer, I am going to assume that the lack of foliage in winter is what has resulted in this difference. 

As you can guess being able to run this graph for almost any possible noise, man made and natural, can be both interesting and informative. The information in these graphs and in the other soundscape data can allow parks to establish base line acoustical data and allow them to make informed management decisions. Some parks like Zion have soundscape management plans, the Grand Canyon used the information to help develop air tour management plans and Yellowstone used soundscape information in their winter use plan. I encourage you to visit the NPS Natural Sounds and Night Skies website if you are interested in more information about soundscape.

The Science of Sound- Soundscape Monitoring at Homestead National Monument

Many people are familiar with the concept of a landscape, and yet they have given no thought to the soundscape. The soundscape of an area is important as the landscape, who wants to go into the wild and see an amazing view, only to hear constant traffic and man-made noises. The National Park Service created the Natural Sounds and Night Skies division to help parks manage their soundscapes.  I was lucky enough to attend a training with some of the NPS Natural Sounds staff in Denver back in May of this year. The training explained the mission of the Natural Sounds program, trained us in the set-up and take-down of acoustical monitoring equipment, and the analysis of all the data collected.

The National Park Service Management Policy from 2006 states in section 4.9 : Park natural soundscape resources encompass all the natural sounds that occur in parks, including the physical capacity for transmitting those natural sounds and the interrelationships among park natural sounds of different frequencies and volumes. Natural sounds occur within and beyond the range of sounds that humans can perceive, and they can be transmitted through air, water, or solid materials. The National Park Service will preserve, to the greatest extent possible, the natural soundscapes of parks. The Service will restore to the natural condition wherever possible those park soundscapes that have become degraded by unnatural sounds (noise), and will protect natural soundscapes from unacceptable impacts. (http://www.nps.gov/policy/mp/policies.html#_Toc157232745) All of the data collected allows parks to establish base line data and help them to create management plans to protect soundscape and help to restore soundscapes in areas where they have been degraded. 

Soundscapes are important for many reasons, among them allowing animals to hunt and visitors to appreciate the sights and sounds of the parks. If you are interested in more information about the importance of sound please visit the NPS Natural Sounds and Night Skies website at: http://www.nature.nps.gov/sound/

Homestead National Monument of America realized the importance of sounds on the monument and reached out to the NPS Natural Sounds and Night Skies program. The monument purchased the necessary equipment to begin gathering acoustical data. The equipment included a SPL (Sound Pressure Level) meter, microphone, mp3 recorder, anemometer (wind), battery and tripods. In August of 2011, a technician from the Natural sounds program came to the monument to teach Natural Resource Management Specialist Jesse Bolli how to set up/take down the equipment and transfer the data to the computer. 

Jesse began to collect data from various sites during the fall and winter. The equipment normally gathers data for approximately 20 days at each site. Jesse set up the equipment 5 times before I arrived on site and we have set it up together once since I received my training. This left me with 6 sets of data to analyze. The NPS Natural Sounds program has developed a program call the Acoustical Monitoring Toolbox. I use many of the features of this program to turn the raw data into something more understandable. The next four graphics are spectrograms for one day at two different sites. I created these images using the AMT (Acoustical Monitoring Toolbox). The first image is of a site close to the road. The more yellow in an image indicates that it is loud, blue colors indicate quieter sounds. All of the white/yellow spikes indicate when a vehicle passed. The second graphic is for the same day at the some site, but is corrected to show only the frequencies that the human ear can pick up. The last two graphics are for a site that is in the woods and much further from the road (site 4). The fact that there is much more blue than yellow shows that the second site is much quieter than the first site. It is also a good example of how it is louder during the day time hours than in the nighttime hours.

Spectrogram- Site 1

Spectrogram (A-weighted) adjusted for human hearing, Site 1

Spectrogram, Site 4

Spectrogram (A-weighted) adjusted for human hearing, Site 4

This graphic was created using the AMT and a program called 'R' running a script created by the Natural Sounds program. It compares how loud a noise is and at what frequency it is at. These graphs are interesting to look at as they split up day and night and show ranges where transportation, conversation, and song birds fall.

The biggest part of data analysis is listening to the sounds that were recorded. For each site 8 days are analyzed. The AMT has a program that splits the audio into 10 seconds clips for every 2 minutes, meaning that you listened to 2 hours of audio per day analyzed. The audio is then listened to in a program call the Listening Center, which allows the listener to assign a number to each individual sound. Once numbers are assigned, the data can be ran through the 'R' program to create graphic that can show what percentage of time trucks or birds or any specific sound was heard.

Screen shot of Listening Center.

 The anemometer gathers wind speed data, which is important in choosing what days are analyzed. Days with little wind are much easier to listen to. It also allows us to see what days or times may not be analyzed by AMT software, since days with wind speeds above 5 m/s (meter per second) are not analyzed.

Wind Data

The following two tables were created by the Natural Sounds program as a base to compare site specific numbers to.

Sound pressure level examples
Park Sound Sources	Common Sound Sources	dBA
Volcano crater (HALE)	Human breathing at 3m	10
Leaves rustling (CANY)	Whispering	20
Crickets at 5m (ZION)	Residential area at night	40
Conversation at 5m (WHMI)	Busy restaurant	60
Snowcoach at 30m (YELL)	Curbside of busy street	80
Thunder (ARCH)	Jackhammer at 2m	100
Military jet at 100m AGL(YUCH)	Train horn at 1m	120

Effects of sound pressure levels on humans
SPL (dBA)	Relevance
35	Blood pressure and heart rate increase in sleeping humans (Haralabidis et al., 2008)
45	World Health Organization’s recommendation for maximum noise levels inside bedrooms (Berglund, Lindvall, and Schwela, 1999)
52	Speech interference for interpretive programs (U.S. Environmental Protection Agency, 1974)
60	Speech interruption for normal conversation (U.S. Environmental Protection Agency, 1974)

I created the following two tables using the data collected by the SPL (Sound Pressure Level) meter. The 20-1,250 range is the lower frequencies, which consists of mainly traffic, while the 12.5-20,000 includes all of the frequencies that were collected. The first table shows the percent time that noise was above a certain level, it is broken up by day an nigh hours and shows data for two different seasons at the same site.

Percent time above for summer and winter
Site	Frequency (Hz)	% Time above sound level: 0700 to 1900				% Time above sound level: 1900to 0700
		35dBA	45dBA	52dBA	60dBA	35dBa	45dBA	52dBA	60dBA
HOME001 Winter	20-1,250	88.2	15.84	1.73	0.04	83.40	9.33	0.49	0.01
	12.5-20,000	92.02	18.77	2.21	0.05	85.15	11.09	0.58	0.01
HOME001 Summer	20-1,250	93.87	10.71	1.56	0.03	69.13	2.78	0.15	0.00
	12.5-20,000	100	99.93	73.81	0.32	100	100	91.76	28.49

Exceedence levels (Lx) represent the sound pressure levels exceeded x percent during the  given measurement period (e.g. L90 is the SPL that has been exceeded 90% of the time). For the following table, the top value reports the Lx for the 20 – 1,250 Hz subset of the frequency range, and the bottom Lx value is calculated from the 12.5 – 20,000 Hz spectrum.  Exceedence levels for existing conditions
Site	Frequency (Hz)	Exceedence levels (dBA): 0700 to 1900			Exceedence levels (dBA): 1900 to 0700
		L90	L50	L10	L90	L50	L10
HOME001 Winter	20-1,250	35.2	40.1	45.5	35.7	38.8	43.3
	12.5-20,000	35.8	40.7	46.4	35.9	39.2	43.7
HOME001 Summer	20-1,250	36.0	39.1	44.6	34.8	36.6	40.3
	12.5-20,000	51.9	53.6	55.2	57.9	59.0	60.0