Outdoor sound propagation Research Papers (original) (raw)

Industrial facilities typically include equipment installed (1) in a free field at some elevation above the terrain (e.g. wind turbines, vents, exhaust stacks, flares etc.) and (2) on top of floating screens (e.g. standard equipment... more

Industrial facilities typically include equipment installed (1) in a free field at some elevation above the terrain (e.g. wind turbines, vents, exhaust stacks, flares etc.) and (2) on top of floating screens (e.g. standard equipment mounted on steel decking). Noise impacts from such equipment are routinely assessed with the ISO 9613-2 prediction method for the purposes of noise control design and occupational noise studies. There are, however, assumptions and limitations inherent to this method which are directly linked to the ground effect attenuation mechanism. The main concern is that the noise assessments are conducted at very short distances (typically less than 100 m) thus potentially undermining the stated accuracy of the prediction method. Furthermore, ISO 9613-2 is ambiguous in its definition of source emission properties and ways to account for the apparent increase in sound power of sources located close to reflecting surfaces.
Investigation presented in this paper relies on an idealized test case and a realistic industrial scenario, both modelled to examine the ISO 9613-2 ground effect calculation methods as implemented in SoundPLAN v7.3. The results indicate that both specified methods fail to perform as expected when simulating unobstructed short-range sound propagation over hard ground and at sharp angles of sound incidence (due to elevated and closely spaced sources and receivers).

The aim of this study is to investigate the misconception in Sound Propagationn topic, within the direction of studentss opinions that can be occurred by using different teaching methods all together. The study includes activities based... more

The aim of this study is to investigate the misconception in Sound Propagationn topic, within the direction of studentss opinions that can be occurred by using different teaching methods all together. The study includes activities based on 5E learning model, conceptual change texts, study sheet supported by analogies, and computer-assisted teaching materials. The sample of this qualitative study is made up of 8 students at 5 th grade from a secondary school in Trabzon. Semi-constructed interview is used as data collection tool. Data collected after the analysis of interview are transferred to the reader without any deterioration in meaning. It is found out that, using different methods all together in Sound Propagationn topic is more effective and misconceptions are removed at the end of the study.

The process of performing an Environmental Impact Assessment includes the study of noise propagation. Often, the path from a noise source to a noise sensitive location involves complicated mechanisms of sound transmission. These... more

The process of performing an Environmental Impact Assessment includes the study of noise propagation. Often, the path from a noise source to a noise sensitive location involves complicated mechanisms of sound transmission. These mechanisms may relate to diffraction & reflections from obstacles (natural or man made), ground properties, and meteorological conditions. The International Standards Organization proposes with standard ISO9613-2, methods by which to calculate these effects. While they are relatively easy to implement, they underestimate the true workings of the aforementioned mechanisms. In this paper, we present the OTL - Terrain software application, which accurately and precisely simulates outdoor sound propagation. The software application can be used for the prediction of environmental noise and the design of control measures. OTL - Terrain is an application which uses geometrical acoustics (GA) and models the propagation of sound in terms of rays. The tool makes use of the image source method (ISM) combined with visibility tracing techniques to implement a novel method of path-detection, taking both reflection and diffraction effects into account. Calculations utilize the predicted reflections from finite-sized objects with Fresnel zone corrections, an unlimited order of diffraction, and atmospheric turbulence. This paper presents a comparison of the predictions made by the OTL – Terrain application, the methods proposed by ISO, and the published results from experimental data.

Background: Assessing the active space of the various types of information encoded by songbirds' vocalizations is important to address questions related to species ecology (e.g. spacing of individuals), as well as social behavior (e.g.... more

Background: Assessing the active space of the various types of information encoded by songbirds' vocalizations is important to address questions related to species ecology (e.g. spacing of individuals), as well as social behavior (e.g. territorial and/or mating strategies). Up to now, most of the previous studies have investigated the degradation of species-specific related information (species identity), and there is a gap of knowledge of how finer-grained information (e.g. individual identity) can transmit through the environment. Here we studied how the individual signature coded in the zebra finch long distance contact call degrades with propagation.

The most important question for anyone born in London is ‘Are you a Cockney?’ Only those born within the sound of Bow bells can truthfully answer the question with a resounding ‘yes.’ ‘Cockney’ is a term of pride in the heart of the East... more

The most important question for anyone born in London is ‘Are you a Cockney?’ Only those born within the sound of Bow bells can truthfully answer the question with a resounding ‘yes.’ ‘Cockney’ is a term of pride in the heart of the East End, an area recently made internationally famous to a new audience due to the global success of the TV series ‘Call the Midwife,’ set in Poplar. Here we use simple physics to determine the greatest distance that you can be born and still hear the peal of the bells. As such, it should appeal to all those teaching the physics of waves, or sound, in the Greater London area—and beyond.

Simple Summary: African savanna elephants are highly social and exhibit a complex vocal communication system. They use a low-frequency contact call (termed 'rumble') to maintain social contact over long distances. As sound travels through... more

Simple Summary: African savanna elephants are highly social and exhibit a complex vocal communication system. They use a low-frequency contact call (termed 'rumble') to maintain social contact over long distances. As sound travels through the environment, however, its intensity level decreases. We used specialized computer software to manipulate acoustic components in male rumbles and simulated different body sizes (large and small). The rumbles were broadcasted and re-recorded at different distances at the Addo Elephant National Park, South Africa. This propagation experiment enabled us to investigate which acoustic components and information content can be transmitted efficiently up to 1.5 km. The results confirm that male rumbles potentially encode information about body size, yet transmission success decreased with distance. Our findings inform on how the environment can influence propagation of savanna elephant rumbles and what kind of information might be transmitted successfully over distance. Abstract: African savanna elephants live in dynamic fission–fusion societies and exhibit a sophisticated vocal communication system. Their most frequent call-type is the 'rumble', with a fundamental frequency (which refers to the lowest vocal fold vibration rate when producing a vocalization) near or in the infrasonic range. Rumbles are used in a wide variety of behavioral contexts, for short-and long-distance communication, and convey contextual and physical information. For example, maturity (age and size) is encoded in male rumbles by formant frequencies (the resonance frequencies of the vocal tract), having the most informative power. As sound propagates, however, its spectral and temporal structures degrade progressively. Our study used manipulated and resynthesized male social rumbles to simulate large and small individuals (based on different formant values) to quantify whether this phenotypic information efficiently transmits over long distances. To examine transmission efficiency and the potential influences of ecological factors, we broadcasted and re-recorded rumbles at distances of up to 1.5 km in two different habitats at the Addo Elephant National Park, South Africa. Our results show that rumbles were affected by spectral–temporal degradation over distance. Interestingly and unlike previous findings, the transmission of formants was better than that of the fundamental frequency. Our findings demonstrate the importance of formant frequencies for the efficiency of rumble propagation and the transmission of information content in a savanna elephant's natural habitat.

African savanna elephants live in dynamic fission⁻fusion societies and exhibit a sophisticated vocal communication system. Their most frequent call-type is the 'rumble', with a fundamental frequency (which refers to the lowest... more

African savanna elephants live in dynamic fission⁻fusion societies and exhibit a sophisticated vocal communication system. Their most frequent call-type is the 'rumble', with a fundamental frequency (which refers to the lowest vocal fold vibration rate when producing a vocalization) near or in the infrasonic range. Rumbles are used in a wide variety of behavioral contexts, for short- and long-distance communication, and convey contextual and physical information. For example, maturity (age and size) is encoded in male rumbles by formant frequencies (the resonance frequencies of the vocal tract), having the most informative power. As sound propagates, however, its spectral and temporal structures degrade progressively. Our study used manipulated and resynthesized male social rumbles to simulate large and small individuals (based on different formant values) to quantify whether this phenotypic information efficiently transmits over long distances. To examine transmission effic...