Category: (((—Acoustics Engineering—))))
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Community Noise and Vibration Sources and Control
16.3.1 Traffic Noise Sources There are several reasons for the emergence of traffic noise as the main source of community noise annoyance in most developed countries. The power–weight ratio of trucks and cars has been constantly increased to permit higher payloads and more speed and acceleration; the resulting higher power engines are usually noisier than…
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Assessment of Community Noise Annoyance
Several noise indicators and rating measures are in use. The equivalent sound pressure level Leq (see Section 6.8 of this book) is used in many countries for the assessment of road traffic noise, although the statistical 10% level L10 (see Section 6.11 of this book) is used in Australia, Hong Kong, and the United Kingdom for target values and insulation regulations for new…
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Introduction
The main sources of urban community noise are (i) road traffic, that is, trucks, cars, and motorcycles, (ii) aircraft/airport noise, (iii) railroads, (iv) construction noise, (v) noise from light and heavy industry, and (vi) noise from recreation activities. Road traffic noise is the most important of these and is discussed in this chapter in some…
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Airport Noise Control
One of the major environmental noise problems throughout the world is the noise associated with civil aircraft operations nearby airports. In the US, the Federal Aviation Administration (FAA) recognizes that airport noise issues can be highly technical and complex. The European Union (EU) has also recognized the problem and noise emission limitations from civil aircraft have been in force…
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Aircraft Cabin Noise and Vibration and Its Control
15.5.1 Passive Noise and Vibration Control Low interior cabin noise is important for passenger and crew comfort [13]. High cabin noise levels experienced in passenger jet aircraft in the 1960s and 1970s have now been considerably reduced by the use of turbofan engines instead of noisy pure jet engines. Obtaining satisfactory cabin noise environments, which…
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Helicopter and Rotor Noise
The generation of helicopter rotor noise is very complicated [11]. Sources of helicopter noise include (i) main rotor, (ii) tail rotor, (iii) the engines, and (iv) the drive train components. The dominant noise contributors are the main rotor and the tail rotor. Engine noise is normally less important, although for large helicopters engine noise can be…
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Propeller and Rotor Noise Sources and Control
As described in Ref, propellers are used on small general aviation aircraft as well as small to medium‐sized passenger airliners (See Figure 15.2). In small general aviation aircraft, propellers operate with a fixed‐blade pitch. In larger general aviation and commuter aircraft, they operate with adjustable pitch to improve aircraft take‐off and flight performance. Smaller aircraft have…
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Jet Engine Noise Sources and Control
The introduction of commercial passenger jet aircraft in the 1950s brought increasing complaints from people living near airports. Not only were the jet engines noisier than corresponding piston engines on airliners, since they were more powerful, but the noise was more disturbing because it had a higher frequency content than piston engines. This was most…
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Introduction
The number of aircraft used for civilian and military air transportation has increased steadily during the last decades. Thus, aircraft noise has been a problem for people living in the vicinity of airports for many years. In the case of aircraft and helicopters, similar power plant and motion‐related noise sources as in surface transportation vehicles…
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Noise And Vibration Control in Ships
Many of the same noise problems exist in passenger ships as in surface transportation vehicles and aircraft. Airborne and structure‐borne paths from noise and vibration sources can be of similar and sometimes of equal concern during different ship operations. The main sources include the power plant machinery and the propulsion units including screws and propellers. Figure…