Voice Biomechanics and Acoustics Laboratory Department of Communicative Sciences and Disorders College of Communication Arts & Sciences Michigan State University 1026 Red Cedar Road East Lansing, MI 48824
Popular version of paper 3aAB7, “Construction noise impact on wild birds” Presented Tuesday morning, May 25, 2016, 10:20, Salon I 171st ASA Meeting, Salt Lake City
Content Almost all bird species use acoustic signals to communicate or recognize biological signals – to mate, to detect the sounds of predators and/or prey, to perform mate selection, to defend their territory, and to perform social activities. Noise generated from human activities (in particular by infrastructure and construction sites) has a strong impact on the physiology and behaviour of birds. In this work, a quantitative method for evaluating the impact of noise on wild birds is proposed. The method combines the results of previous studies that considered the effect of noise on birds and involved noise mapping evaluations. A forecast noise simulation was used to generate maps of (1) masking-annoyance areas and (2) potential density variation.
An example of application of the masking-annoyance areas method is shown in Figure 1. If a bird is in the Zone 1 (in purple), traffic noise and construction noise can potentially result in hearing loss and threshold shift. A temporary elevation of the bird’s hearing threshold and a masking of important communication signals can occur in the Zone 2 (in red). Zone 3 (in orange), 4 (in yellow) and 5 (in light green) are characterized by a high, medium and low level of signal masking, respectively. Once the level of noise generated by human activities falls below ambient noise levels in the critical frequencies for communication (2–8 kHz), masking of communication signals is no longer an issue. However, low-frequency noise, such as the rumble of a truck, may still potentially cause other behavioural and/or physiological effects (Zone 6, in green). No effects of any kind occur on the birds in Zone 7 (in dark green). The roles for Zone definition are based on the results of Dooling and Popper. [1]
Figure 1 Mapping of the interaction areas of noise effect on birds within the 7 zones for a project without (a) and with mitigations (b).
Waterman et al. [2] and Reijnem et al. [3-4-5] proposed a trend of the potential variation in birds density in relationship with the noise levels present in the area. This trend shows no effect on density when the noise levels are lower than 45 dB(A), while there is a rapid decrease (with a quadratic shape) for higher levels. An example of the potential decrease in bird density for a project with and without mitigations is shown in Figure 2. The blue areas are the areas where the birds’ density is not influenced by the noise, while the red ones are the areas from where the birds are leaving because the noise levels are too high.
This methodology permits a localization of the areas with greater impacts on birds. The mitigation interventions should be focused on these areas in order to balance bird habitat conservation and human use of land.
Figure 2 Potential decrease in bird density for a project without (a) and with mitigations (b).
References
R. J. Dooling and A. N. Popper, The effects of highway noise on birds, Report prepared for The California Department of Transportation Division of Environmental Analysis, (2007).
E. Waterman, I. Tulp, R. Reijnen, K. Krijgsveld and C. ter Braak, “Noise disturbance of meadow birds by railway noise”, Inter-Noise2004, (2004).
R. Reijnen and R. Foppen, “The effects of car traffic on breeding bird populations in woodland. IV. Influence of population size on the reduction of density close to the highway”, J. Appl. Ecol. 32(3), 481-491, (1995).
R. Reijnen, R. Foppen, C. ter Braak and J. Thissen, “The effects of car traffic on breeding bird populations in Woodland. III. Reduction of density in relation to the proximity of main roads”, J. Appl. Ecol. 32(1), 187-202, (1995).
R. Reijnen, G. Veenbaas and R. Foppen, Predicting the Effects of Motorway Traffic on Breeding Bird Populations. Ministry of Transport and Public Works, Delft, Netherlands, (1995).
Suzi Wiseman – sw1210txstate@gmail.com Texas State University-San Marcos Environmental Geography 601 University Drive, San Marcos, Texas 78666 Preston S. Wilson – wilsonps@austin.utexas.edu University of Texas at Austin Mechanical Engineering Department 1 University Station C2200 Austin, TX 78712
Popular version of paper 2aAB7, “Nocturnal peace at a Conservation Center for Species Survival?” Presented Tuesday morning, May 19, 2015 at 10.15am 169th ASA Meeting, Pittsburgh
The acoustic environment is essential to wildlife, providing vital information about prey and predators and the activities of other living creatures (biophonic information) (Wilson, 1984), about changing weather conditions and occasionally geophysical movement (geophonic), and about human activities (anthrophonic) (Krause 1987). Small sounds can be as critical as loud, depending on the species trying to listen. Some hear infrasonically (too low for humans, generally considered below 20 Hz), others ultrasonically (too high, above 20 kHz). Biophonic soundscapes frequently exhibit temporal and seasonal patterns, for example a dawn “chorus”, mating and nurturing calls, diurnal and crepuscular events.
Some people are attracted to large parks due in part to their “peace and quiet” (McKenna 2013). But even in a desert, a snake may be heard to slither or wind may sigh between rocks. Does silence in fact exist? Finding truly quiet places, in nature or the built environment is increasingly difficult. Even in our anechoic chamber, which was purpose built to be extremely quiet, located in the heart of our now very crowded and busy urban campus, we became aware of infrasound that penetrated, possibly from nearby construction equipment or from heavy traffic that was not nearly as common when the chamber was first built more than 30 years ago. Is anywhere that contains life actually silent?
Figure 1: In the top window, the waveform in blue indicates the amplitude over time each occasion that a pulse of sound was broadcast in the anechoic chamber, as shown in the spectrogram in the lower window, where the frequency is shown over the same time, and the color indicates the intensity of the sound (red being more intense than blue). Considerable very low frequency sound was evident and can be seen between the pulses in the waveform (which should be silent), and throughout at the bottom of the spectrogram. The blue dotted vertical lines show harmonics that were generated within the loudspeaker system. (Measurements shown in this study were by a Roland R26 recorder with Earthworks M23 measurement microphones with frequency response 9Hz to 23kHz ±1/-3dB)
As human populations increase, so do all forms of anthrophonic noise, often masking the sounds of nature. Does this noise cease at night, especially if well away from major cities and when humans are not close-by? This study analyzed the soundscape continuously recorded beside the southern white rhinoceros (Ceratotherium simum simum) enclosure at Fossil Rim Wildlife Center, about 75 miles southwest of Dallas Texas for a week during Fall 2013, to determine the quietest period each night and the acoustic environment in which these periods tended to occur. Rhinos hear infrasound, so the soundscape was measured from 0.1 Hz to 22,050 kHz. Since frequencies below 9 Hz still need to be confirmed however, these lowest frequencies were removed from this portion of the study.
Figure 2: Part of the white rhinoceros enclosure of Fossil Rim Wildlife Center, looking towards the tree line where the central recorder was placed
Figure 3: The sound pressure level throughout a relatively quiet day at the rhino enclosure. The loudest sounds were normally vehicles, machinery, equipment, aircraft, and crows. The 9pm weather front was a major contrast.
Figure 3 illustrates the rhythm of a day at Fossil Rim as shown by the sound level of a fairly typical 24 hours starting from midnight, apart from the evening storm. As often occurred, the quietest period was between midnight and the dawn chorus.
While there were times during the day when birds and insects were their most active and anthrophonic noise was not heard above them, it was discovered that all quiet periods contained anthrophonic noise, even at night. There was generally a low frequency, low amplitude hum – at times just steady and machine-like and not yet identified – and depending on wind direction, often short hums from traffic on a state highway over a mile away. Quiet periods ranged from a few minutes to almost an hour, usually eventually broken by anthrophonic sounds such as vehicles on a nearby county road, high aircraft, or dogs barking on neighboring ranches. However there was also a strong and informative biophonic presence – from insects to nocturnal birds and wildlife such as coyotes, to sounds made by the rhinos themselves and by other species at Fossil Rim. Geophonic intrusions were generally wind, thunder or rain, possibly hail.
The quietest quarter hour was about 4am on the Friday depicted in figure 3, but even then the absolute sound pressure level averaged 44.7 decibels, about the level of a quiet home or library. The wind was from the south southeast around 10 to 14 mph during this time. Audio clip 1 is the sound of this quiet period.
Figure 4: The quietest quarter hour recorded at Fossil Rim appears between the vertical red selection lines, with an average absolute sound pressure level of 44.5 decibels. The fairly constant waveform shown in blue in the top graph and the low frequency noise at the bottom of the spectrogram seemed to comprise the machine-like hum, the distant traffic hum which varies over time, and insects. The blue flashes between 3 and 5 Hz were mainly bird calls.
By contrast, the loudest of the “quietest nightly periods” was less than six minutes long, around 5am on Wednesday 23rd October, as shown between the vertical red lines in figure 5. Despite being the quietest period that night, it averaged a sound pressure level of 55.5 decibels, which is roughly the equivalent of a spoken conversation.
Figure 5: The loudest “quietest period each night” reveals broadband machine noise (possibly road work equipment somewhere in the district?) which continued for some hours and appears as the blue flecks across all frequencies. The horizontal blue line at 16.5 kHz is characteristic of bats. All species identification is being left to biologists for confirmation. Audio clip 2 is this selection.
Either side of the “quiet” minutes were short bursts of low frequency but intense truck and/or other machine noise indicated in red, some of which partially covered a clang when a rhino hit its fence with its horn, and distant barks, howls, moos and other vocalizations. The noise may have masked the extremely low frequency hums and insects that had been apparent on other nights or to have caused the insects to cease their activity. The strata below 2.5 kHz appear more ragged, indicating they are not being produced in such a uniform way as on quieter nights, and they are partially covered by the blue flecks of machine noise. However the strata at 5.5, 8.5, 11 and especially at 16.5 kHz that appeared on other nights are still evident. They appear to be birds, insects and bats. Audio clip 3 contains the sounds that broke this quiet period.
At no point during the entire week was anything closely approaching “silence” apparent. Krause reports that healthy natural soundscapes comprise a myriad of biophony, and indeed the ecological health of a region can be measured by its diverse voices (Krause 1987). However if these voices are too frequently masked or deterred by anthrophonic noise, animals may be altered behaviorally and physiologically (Pater et al, 2009), as the World Health Organization reports to be the case with humans who are exposed to chronic noise (WHO 1999). Despite some level of anthrophonic noise at most times, Fossil Rim seems to provide a healthy acoustic baseline since so many endangered species proliferate there.
Understanding soundscapes and later investigating any acoustic parameters that may correlate with animals’ behavior and/or physiological responses may lead us to think anew about the environments in which we hold animals captive in conservation, agricultural and even domestic environments, and about wildlife in parts of the world that are being increasingly encroached upon by man.
References: Krause, B. 1987. The niche hypothesis. Whole Earth Review . Wild Sanctuary. ———. 1987. Bio-acoustics: Habitat ambience & ecological balance. Whole Earth Review. Wild Sanctuary. McKenna, Megan F., et al. “Patterns in bioacoustic activity observed in US National Parks.” The Journal of the Acoustical Society of America 134.5 (2013): 4175-4175. Pater, L. L., T. G. Grubb, and D. K. Delaney. 2009. Recommendations for improved assessment of noise impacts on wildlife. The Journal of Wildlife Management 73:788-795. Wilson, E. O. 1984. Biophilia. Harvard University Press. World Health Organization. “Guidelines for community noise”. WHO Expert Taskforce Meeting. London. 1999.
Irene van Kamp, (irene.van.kamp@rivm.nl) Elise van Kempen, Hanneke Kruize, Wim Swart National Institute for Public Health and the Environment Netherlands Pobox 1 Postvak 10 3720 BA BILTHOVEN Netherlands Phone +31629555704
Popular version of paper in session 2aNSa, “Soundscapes and human restoration in green urban areas” Presented Tuesday morning, May 19, 2015, 9:35 AM, Commonwealth 1 169th ASA Meeting, Pittsburgh
Worldwide there is a revival of interest in the positive effect of landscapes, green and blue space, open countryside on human well-being, quality of life, and health especially for urban dwellers. However, most studies do not account for the influence of the acoustic environment in these spaces both in a negative and positive way. One of the few studies in the field, which was done by Kang and Zhang (2010) identified relaxation, communication, dynamics and spatiality as the key factors in the evaluation of urban soundscapes. Remarkable is their finding that the general public and urban designers clearly value public space very different. The latter had a much stronger preference for natural sounds and green spaces than the lay-observers. Do we as professionals tend to exaggerate the value of green and what characteristics of urban green space are key to health, wellbeing and restoration? And what role does the acoustic quality and accompanying social quality play in this? In his famous studies on livable streets Donald Appleyard concluded that in heavy traffic streets the number of contacts with friends, acquaintances and the amount of social interaction in general was much lower. Also people in busy streets had a tendency to describe their environment as being much smaller than their counterparts in quiet streets did. In other words, the acoustic quality affects not only our wellbeing and behavior but also our sense of territory, social cohesion and social interactions. And this concerns all of us: citing Appleyard “nearly everyone in the world lives in a street”.
There is evidence that green or natural areas/wilderness/ or urban environments with natural elements as well as areas with a high sound quality can intrinsically provide restoration through spending time there. Also merely the knowledge that such quiet and green places are available seems to work as a buffer effect between stress and health (Van Kamp, Klaeboe, Brown, and Lercher, 2015 : in Jian Kang and Brigitte Schulte-Fortkamp (Eds) in press).
Recently a European study was performed into the health effect of access and use of green area in four European cities of varying size in Spain, the UK, Netherlands and Lithuania)
At the four study centers people were selected from neighborhoods with varying levels of socioeconomic status and green and blue space. By means of a structured interview information was gathered about availability, use and importance of green space in the immediate environment as well as the sound quality of favorite green areas used for physical activity, social encounters and relaxation. Data are also available about perceived mental/physical health and medication use. This allowed for analyzing the association between indicators of green, restoration and health, while accounting for perceived soundscapes in more detail. In general there are four mechanisms assumed that lead from green and tranquil space to health: via physical activity, via social interactions and relaxation and finally via reduced levels of traffic related air and noise pollution. This paper will explore the role of sound in the process which leads from access and use of green space to restoration and health. So far this aspect has been understudied. There is some indication that certain areas contribute to restoration more than others. Most studies address the restorative effects of natural recreational areas outside the urban environment. The question is whether natural areas within, and in the vicinity of, urban areas contribute to psycho-physiological and mental restoration after stress as well. Does restoration require the absence of urban noise?
Example of an acoustic environment – a New York City Park – with potential restorative outcomes (Photo: A.L. Brown)
