Aaron Hastings

Measurement of the attributes of complex tonal components commonly found in product sound

All rotating components in machinery produce sounds that contain tonal components, and the presence of these tones can significantly affect the quality of the product sound. Tone corrections for metrics based on weighted, average sound pressure level have been used since the late 1960s to assess annoyance due to aircraft noise and to rate climate control machinery. Much research has also been focused on measuring the strength of well separated tones in noise. Metrics such as the Prominence Ratio, the Tone-to-Noise Ratio, and variants, as well as more complex models such as the Joint Nordic Method, Aures Tonalness, and Virtual Pitch, produce values that often correlate well with subjects judgments on the level of the tonal features that they perceive when listening to the sound. However, when sounds are more complex, these metrics do not always work well. Models for the tonalness of two types of tonal sounds are considered here: narrow-band random noise and tones with random frequency fluctuations. The influence of bandwidth and roll-off rate on perceived tonalness are explored for the narrow-band sounds, and the effect of the range and the rate of change of the frequency variation on perceived tonalness is explored for frequency modulated sounds. It was found that roll-off rate affected the perception of tonalness, and that when frequency variations could be tracked or were very small, metrics derived from averaged spectra produced inaccurate predictions of tonalness. Based on the results of these two investigations modifications to tonal metrics are proposed.

Acoustic Characteristics of Hybrid Electric Vehicles and Safety of Blind Pedestrians

Quieter cars, such as electric vehicles and hybrid electric vehicles (HEVs), may reduce auditory cues used by pedestrians to assess the state of nearby traffic and, as a result, their use may have an adverse impact on pedestrian safety. To document differences in the sound levels of HEVs and internal combustion engine (ICE) vehicles, the authors measured the sound pressure levels in one-third octave bands of three HEVs and three corresponding ICE vehicles for the following operating conditions: idle, backing up at 5 mph, approaching at a constant speed (6, 10, 20, 30, and 40 mph), accelerating from stop, and slowing from 20 to 10 mph at 3.28 ft/s2. Sound level results comparing the HEVs with the ICE vehicles are presented. In general, HEVs have lower sound levels than ICE vehicles for operating conditions below 20 mph; but above 20 mph, the sound from road–tire interactions dominates and the sound levels of the two vehicle types converge.

Aircraft noise‐dose‐visitor‐response relations for national parks.

The U.S. National Parks Overflights Act and the Air Tour Management Act require management of air tours over national parks. Unfortunately, past noise‐dose‐response relations do not suffice for predicting response of national park visitors who are not at home, are not exposed for months/years, and are not subject to jets on approach or departure, but instead to low‐flying tour aircraft. Toward filling that insufficiency, this study was designed to understand the complex relationship between in‐park noise exposure and park‐visitor response. The study derives from a decade of visitor surveys and simultaneous sound measurements at ten frontcountry sites (scenic overlooks and short hikes) within four scenic national parks. This talk describes the analysis of these measurements and documents the six resulting dose‐response relations—‐two responses (annoyance and interference with natural quiet and sounds of nature) paired with three response dichotomizations (slightly to extremely, moderately to extremely, and...

Wayside noise measurement and propagation predictions for four motorcycles categories

Motorcycle noise is distinct from other types of road transportation noise and it varies within this general vehicle type based on design characteristics. One-third octave band sound levels that had been measured for four motorcycles categories (cruiser, sport, dual purpose, and touring) using statistical, isolated pass-by techniques for wayside measurements were analyzed. The spectra are dominated by different frequency components depending on the category and these differences have implications on how sound for different categories propagates over extended distances. This is an important consideration for predicting and mitigating motorcycle noise. To illustrate this, these measurements were used to modify a version of the Federal Highway Administrations Traffic Noise Model. This model was then used to predict noise levels at various distances representative of typical receptor locations for the different motorcycle categories. It is expected that accounting for these differences will aid local, state and federal agencies that wish to improve the management of motorcycle noise in their jurisdictions.

Modeling and mapping aircraft noise in National Parks

Commercial air tours are a common source of noise within many national parks, affecting natural and cultural resources as well as visitor experience. To facilitate interactive modeling and mapping of air tour noise exposure, the Volpe National Transportation Systems Center and National Park Service (NPS), in cooperation with the Federal Aviation Administration (FAA), have created an Aviation Noise Analysis and Mapping Tool. This tool contains a library of park noise maps generated by modeling single aircraft operations on routes flown by that aircraft. The creation of this library is computationally intensive and requires considerable expertise to properly configure and run the models. With this tool and library, a broad range of users can interactively explore composite noise exposure generated by air tour traffic scenarios. Composite noise exposure is calculated by summing, across all aircraft and route combinations, the product of the number of flights on each route and the noise generated by each airc...

Aviation Noise and Cardiovascular Health in the United States: a Review of the Evidence and Recommendations for Research Direction

Purpose of the ReviewIn the USA, there is mounting pressure on aviation operators and regulators to address concerns about community impacts of aircraft noise given increasing evidence of adverse health impacts, continuing community complaints, availability of cost-effective programs to reduce exposures to aircraft noise, and more stringent international policies. In the USA, regulation of civil aviation noise is the responsibility of the Federal Aviation Administration (FAA), which requires a “significant body of scientific support,” particularly applicable to the USA, to inform health-based policy and regulatory decisions. However, there have been very few studies investigating the relationship between noise and health in the USA and limited studies across the globe characterizing the effects of aviation noise specifically on cardiovascular health. This review focuses on recent findings on the relationship between aircraft noise and cardiovascular outcomes and directions for future research.Recent FindingsEpidemiological studies generally report statistically significant associations between aircraft noise and adverse cardiovascular outcomes, although with limited evidence within the USA. Sleep disturbance, associated with nighttime noise, has been shown to be a risk factor for cardiovascular disease given associations with inflammatory markers and metabolic changes. Given numerous cardiovascular markers, the most appropriate choices depend on the ultimate objectives of the individual studies.SummaryGiven the state of the literature, future research should leverage emerging tools to estimate aviation, railway, and road traffic noise and apply noise estimates to a range of epidemiological study designs and endpoints to inform causal interpretation and help determine potential intervention strategies.

New methods for measuring and correlating transportation noise frequencies with ultrafine particulate emissions under varying meteorological conditions to inform environmental health studies

Transportation-derived particulate matter and chronic noise exposure frequently occur concomitantly in urban areas. Noise is an important confounder to be evaluated in epidemiological studies, yet few public health studies have included both air pollution and noise in health effects models due to difficulty in demonstrating epidemiologic causal mechanisms and confounding factors in noise and air pollution sampling and analytical methodologies. This study will present a framework for the development of a traffic-noise frequency and particulate emissions correlation model based on frequency-domain analysis of vehicle noise measurements, compared with particulate measurements sampled concurrently at two Greater Boston urban neighborhoods under varying meteorological conditions. The research will present new methods for evaluating bi-seasonal measurement of both transportation noise and associated particulate emissions, with emphasis on Ultrafine Particulates (UFP, <100 nm diameter) from diesel exhausts. The ...

Correlating transportation noise frequencies with ultrafine particulate emissions by source: Implications for environmental health studies

Transportation-derived particulate matter and chronic ambient noise exposure frequently occur concomitantly in urban areas, adversely impacting population health outcomes. Noise is identified as an important confounder in epidemiological studies, yet few health studies have included both air pollution and noise in health effects models. Several noise exposure studies have associated intensity and duration of transportation noise with chronic health effects; comparatively few studies have assessed airborne particulate concentrations with co-exposure to transportation noise of specific frequency. This study will present methodologies for the measurement, visualization and analysis of traffic-noise frequency and particulate emissions developed through concurrent sampling at two Greater Boston locations under varying meteorological conditions. We present methods for evaluating co-located measurement of both transportation noise and associated particulate emissions, with emphasis placed on Ultrafine Particulat...

Aircraft dose-response relations for day-use visitors to backcountry areas in National Parks

The Federal Aviation Administration and National Park Service conducted joint research to better understand visitor response to noise from commercial air tour operations over units of the National Park System. Dose-response relationships developed for heavily visited, frontcountry sites in National Parks showed significant differences in responses between visitors to overlook and short-hike sites, suggesting that activity and visit duration are key influences. An extensive recently collected dataset from backcountry day-use visitors was utilized to further explore these and other influences on dose-response relationships. In this second of two papers on this research, we describe the model-fitting approach used to identify the combination of noise exposure metrics (dose variables) and mediator variables that best predict visitor responses to aircraft noise. The interpretation and application of the best fit model is presented along with the previously developed front-country model. Such dose-response rela...

Development of a tool for modeling snowmobile and snowcoach noise in Yellowstone and Grand Teton National Parks

The National Park Service (NPS) develops winter use plans for Yellowstone and Grand Teton National Parks to help manage the use of Over-Snow Vehicles (OSVs), such as snowmobiles and snowcoaches. The use and management of OSVs in the parks is an issue because of potential environmental impacts and because of actions by environmental, recreational, and commercial groups. The U.S. Department of Transportation, Research and Innovative Technology Administration, John A. Volpe National Transportation Systems Center (the Volpe Center) supported the NPS by modeling the acoustical environment in the parks associated with potential modeling alternatives as well as current and historical conditions. The modeling considered a number of alternatives for inclusion in the NPSs winter use plans. These alternatives affect the type and number of OSVs that are allowed to operate in the parks and where they are allowed to travel. The acoustical modeling was performed by using the Federal Aviation Administrations (FAA) Integrated Noise Model (INM), adapted for use with OSVs. INM adaptation included the development of an over-ground sound propagation model to account for propagation over snow-covered terrain. The Volpe Center also developed a new OSV noise database, which defined OSV noise as a function of speed and source-to-receiver distance, based on previously published OSV acoustical studies and winter 2005-2006 measurements. Vehicle types modeled included two- and four-stroke snowmobiles as well as two- and four-track snowcoaches