December 26, 2004

Jim Cummings

Acoustic Ecology Institute


Citizen Sound Monitoring

Developing concrete metrics and protocols for use in the field

Initial brainstorming, December 2004

The need:

Public lands managers are working to address the diverse user needs resulting from quiet recreation and motorized recreation. While there are many areas designated for “shared use,” it is becoming more common for management and travel plans to designate some areas for quiet use only. (This is most common in winter travel planning, where snowmobiles are the primary or only motorized use; resource concerns are generally limited to disturbance of wildlife, so it is common that noise is a central management factor. By contrast, designation of areas for motorized use in non-snow conditions is more often determined by resource protection/erosion concerns, with noise issues more apt to be secondary.)

While Forest Service personnel talk and plan using terms such as “quiet”, there has been little emphasis on what is meant by this. Given that sound levels change hourly and seasonally due to wind and weather conditions, and that noise levels considered “bothersome” vary widely among users, FS planners have shied away from “chasing noise” in their planning. However, at the Winter Wildlands Alliance 2004 conference Dave Holland expressed interest in hearing about sound metrics and protocols that could be concrete enough to be useful in forest planning.

Members of the Winter Wildlands Alliance have similarly expressed a desire to learn more about concrete approaches to documenting the health of soundscape resources on public lands used for cross-country skiing and snowshoeing. They may be particularly interested in some simple monitoring protocols that they can use in the field to document the current sound sources audible within “quiet” (or shared) recreation zones. This data could be used to confirm the effectiveness of current planning approaches, or to inform future designations of recreation zones on public lands.

Acoustic Ecology Institute is available to help facilitate this process, which will likely be centered on adapting some well-established soundscape monitoring techniques that have been widely used by the National Park Service and FAA.

The goals:

  • Facilitate dialogue among recreation groups and agency personnel aimed at establishing metrics for monitoring the success of attempts to provide for quiet recreation.
  • Generate one or more prototypes of citizen monitoring protocols for initial field testing during the winter of 2004-5.
  • Collaborate with agency staff to ensure that monitoring protocols and metrics will be useful and applicable to decision-making in resource management planning and travel planning.
  • Create a final set of citizen monitoring metrics and protocols, perhaps following further field testing in the winter of 2005-6.
  • Initiate wider use of the metrics and protocol standards by citizen monitoring teams, beginning in the winter of 2006-7.

Initial thoughts:

The National Park Service has been working for several years to develop concrete approaches to managing the soundscape as a resource. Some of their methods may be applicable to citizen monitoring of sound on other public lands. For example, in the Grand Canyon, where airplane over-flights have been subject to extensive management planning, simple metrics have been developed to reflect management goals; for example, their stated management goal of “substantially” restoring natural quiet has been defined to mean “no aircraft audible for 75-100% of the day.”

Some soundscape studies have relied on expensive field research involving manned and autonomous recorders (eg, Sequoia-Kings Canyon NP, Grand Canyon NP). One government contractor (HMMH) has advocated the creation of a Palm Pilot program that could be distributed to park visitors in order to gather much more extensive baseline soundscape data.

Another affordable approach that has a good track record relies on using citizens to do simple monitoring of audible sound intrusions; this approach can generate a large data set, spread out over time and territory. Log sheets can be developed, which use consistent standards for use in diverse landscapes. There would remain a need for some volunteer, or student, time to be devoted to analysis of the resulting data.

The use of such an approach is well established. The NPS uses a Soundscape Monitoring Form (officially entitled the “Sound Identification Data Sheet”) for logging sounds of all types during field sessions. Such forms have been used in conjunction with recordings, and as stand-alone tools, with simple audibility as the threshold. According to project managers who have worked with them, it is fairly easy to train people to get consistent results. This method has been accepted by NPS and FAA as the gold standard to determine audibility of aircraft, and is often used to field-test computer models of sound propagation. Monitoring such as this have been used in Grand Canyon, Hawaii Volcanoes, Haleakala, Zion, White Sands National Monument, and Bryce Canyon.

Among the resources at our disposal are two members of the AEI Advisory Council: Nick Miller of HMMH, a consulting firm that has worked for the NPS and FAA on several soundscape studies, and Bob Rossman of the NPS Soundscape Program.

If this effort to create useful metrics is successful, it is quite likely that land managers will use a variety of standards or goals in different areas. That is, some areas may be managed to be “quiet” half the time, others 90% of the time, and perhaps some will be designed to be virtually free of all land-based motorized sounds (acknowledging that in most cases, we cannot manage for airplane over-flights).

While the initial context for our work is winter recreation, it is quite possible that the approaches we develop could be adapted for use in citizen monitoring of OHV use in the other three seasons as well. Development of some standards, metrics, and protocols could be very useful as scoping begins on individual forest travel planning.

For me at least, the goal here is not to create ammunition for diminishing the opportunities for motorized recreation; rather, the underlying desire is to provide some resources and information that might help inform management decisions by adding some concrete metrics for use when forest or travel planning is attempting to address sonic impacts.

I am not thinking about trying to do dB-level measurements of individual machines (ie enforcing technology standards); this is a different sort of law enforcement question. Likewise, my prejudice is toward sound logs rather than dB-level measurements in the field as well, largely in order to embrace a much larger population of potential citizen monitors. We can do some training aimed at helping citizen monitors learn to rate the relative sound levels of motorized sounds against the current sounds of wind, skiers, or conversation. That is, focus on how the various aspects of the soundscape compare to each other, rather than attempting to generate absolute sound level measurements. There may be a role for dB-level measurements, as well; we should consider this.

Questions for Initial Discussion:

What sorts of metrics would make sense to try to track in field monitoring?

Percentage of time motors are audible

Interval of time between motors being audible (ie length of periods of “natural quiet”)

Number of motor sounds audible in a given period

How to rate closeness of motor? Some sort of near/far rating (too subjective??) Visible or not visible? What if it’s just out of sight through trees? That’s more impact than if heard over a ridge or across a valley. . . How to log these sorts of things?

If roads are audible, then should we even listen for snowmobiles? Are there times near roads when it can still matter? Is our focus/goal to measure all sonic impacts, or just listen for snowmobiles/OHVs? (this could be determined on a case-by-case basis)

What areas should be chosen for initial prototype monitoring? Areas that are designed to be really quiet, or ones that are near snowmobiling areas? (ie, should we listen to see how quiet the “quiet” areas really are, or is it also useful to get a sense of how much the “close proximity” areas are being impacted by noise? Or both? What are winter recreation groups and the USFS interested in monitoring?)