: Assessing and mitigating impacts of military training on threatened and endangered species (TES) is a high priority for the Army. Noise is one impact of concern that is not understood very well. This literature review looks at research on the effects on wildlife of noise associated with military training, especially vehicle noise, artillery, small arms and other blast noise, and helicopter noise. Physical (acoustic) and biological principles are briefly reviewed and traumatic, physiological, behavioral, and population-level effects are discussed. Direct physiological effects of noise on wildlife are difficult to measure and although the processes are technically successful, they do not indicate the individual's health or chances of survival. Behavioral effects that might decrease chances of surviving and reproducing include retreat from favorable habitat near noise sources and reduction of time spent feeding, with resulting energy depletion. The literature contains a preponderance of small, disconnected, anecdotal or correlational studies as opposed to coherent programs of controlled experiments. Future research should stress quantification of exposure of subjects to noise, experimental approaches such as broadcasting accurate recordings of sounds, and observer effects.

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Effects of Military Noise on Wildlife. A Literature Review.

Behavioural responses of feral goats (Capra hircus) to helicopters

A passive acoustic system, consisting of a set of acoustic nodes and a central processing node, is a good candidate for the covert detection of low flying aircraft as they cross our nation's borders. Small arrays of microphones have been used to estimate aircraft speed, heading, frequency spectrum and altitude at the closest point of approach. We extend this work by considering maneuvering aircraft and by testing a narrowband algorithm that gives angle estimates sooner, and over a longer period of time, than the broadband version. A new narrowband algorithm is provided for estimating position versus time as the aircraft flies through a grid of widely spaced omni-directional microphones (separated by several miles). We classify aircraft as helicopter, piston engine aircraft (specifically, numbers of propeller blades and cylinders), turboprop aircraft or jet aircraft. Our approach has been validated via testing at various airports against ground truth data.

Acoustic detection of low flying aircraft

A wind tunnel test to study the effects of geometric scale on acoustics and to investigate the applicability of very small scale models for the study of acoustic characteristics of helicopter rotors was conducted in the United Technologies Research Center Acoustic Research Tunnel. The results show that the Reynolds number effects significantly alter the Blade-Vortex-Interaction (BVI) Noise characteristics by enhancing the lower frequency content and suppressing the higher frequency content. In the time domain this is observed as an inverted thickness noise impulse rather than the typical positive-negative impulse of BVI noise. At higher advance ratio conditions, in the absence of BVI, the 1/20 scale model acoustic trends with Mach number follow those of larger scale models. However, the 1/20 scale model acoustic trends appear to indicate stall at higher thrust and advance ratio conditions.

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Acoustic characteristics of 1/20-scale model helicopter rotors

Abstract According to the applicable regulations, in the case of a decision on the location of an investment consisting in the construction and commissioning of a helicopter landing field, it is necessary to carry out an environmental impact assessment. At the same time, due to the emission of noise related to the expected change of acoustic climate parameters, the indicators required under the applicable law related to building acoustics and also impact of vibration on the structure of buildings should be taken into account. The article discusses particular groups of issues related to the assessment of the impact of helicopter landing field on the environment and the hospital building. On the basis of the presented results of analyzes, a postulate concerning the necessity of introducing a comprehensive assessment methodology, including specific groups of issues, was formulated.

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The Analysis of Hospital Helicopter Landing Sites Location in Terms of their Vibroacoustic Impact

: This report establishes the current (1982) FAA helicopter noise data base for use in environmental impact assessment. The report sets out assumptions, methodologies, and techniques used in arriving at noise-exposure-versus-distance relationships. Noise data are provided for 15 helicopters, including five flight regimes each: takeoff, approach, level flyover, hover in-ground-effect (HIGE) and hover out-of-ground effect (HOGE). When possible, level flyover data are presented for a variety of airspeeds. Sound exposure level (SEL) is provided for all operational modes except hover. In the case of hover operations (both HOGE and HIGE), the maximum A-Weighted Sound Level (LAM) is identified as a function of distance. The report also includes a discussion of helicopter performance characteristics required for full computer modeling of helicopter/heliport noise exposure. (Author)

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Helicopter Noise Exposure Curves for Use in Environmental Impact Assessment.

This document presents noise data for the Sikorsky UH-60A Blackhawk, the Sikorsky S-76 Spirit, the Agusta A-109 and the Bell 206-L The acoustical data are accompanied by phototheodolite tracking data, cockpit instrument panel photo data, and meteorological data acquired from radiosonde balloons Acoustical metrics include both noise certification metrics (EPNL, PNLT, PNL) as well as community/airport noise assessment metrics (SEL, dBA) Noise data have been acquired systematically to identify variations in level with variations in helicopter airspeed and altitude Data contained in this report provide essential information for development of helicopter noise exposure contours as well as further evaluation of ICAO helicopter noise certification standards

Edward J. Rickley

Papers

Helicopter Noise Exposure Curves for Use in Environmental Impact Assessment.

Helicopter noise definition report: uh-60a, s-76, a-109, 206-l

Noise measurement flight test for Aerospatiale AS 355F Twin Star helicopter : data and analyses