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CUSTIC software: Noise pollution map produced by three sources (XY-plane)

Noise pollution software: vehicle noise, noise pollution control, industrial noise control, environmental engineering, environmental consultancy service, environment simulation, environmental modeling and environmental impact assessment.

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Frequency Characteristics of Noise

The response of human beings to sound depends strongly on the frequency of sound. In general, people are less sensitive to sounds of low frequency, such as 100 hertz (Hz)*, than to sounds at 1000 Hz; also at high frequencies such as 8000 Hz, sensitivity decreases. Two basic approaches to compensate for this difference in response to different frequencies are (1) to segment the sound pressure spectrum into a series of contiguous frequency bands by electrical filters so as to display the distribution of sound energy over the frequency range; or (2) to apply a weighting to the overall spectrum in such a way that the sounds at various frequencies are weighted in much the same way as the human ear hears them.

In the first approach a sound is segmented into sound pressure levels in 24 different frequency bands, which may be used to calculate an estimate of the "loudness" or "noisiness" sensation which the sound may be expected to cause. This form of analysis into bands is usually employed when detailed engineering studies of noise sources are required. It is much too complicated for monitoring noise exposure.

To perform such analysis, especially for time-varying sounds, requires a very complex set of equipment. Fortunately, much of this complication can be avoided by using approach 2, i.e., by the use of a special electrical weighting network in the measurement system. This network weights the contributions of sounds of different frequency so that the response of the average human ear is simulated. Each frequency of the noise then contributes to the total reading by an amount approximately proportional to the subjective response associated with that frequency. Measurement of the overall noise with a sound level meter incorporating such a weighting network yields a single number, such as the A-weighted Sound Level, or simply A-level, in decibels. For zoning and monitoring purposes, this marks an enormous simplification. For this reason, the A-level has been adopted in large-scale surveys of city noise coming from a variety of sources. It is widely accepted as an adequate way to deal with the ear's differing sensitivity to sounds of different frequency, including assessment of noise with respect to its potential for causing hearing loss. Despite the fact that more detailed analysis is frequently required for engineering noise control, the results of such noise control are adequately described by the simple measure of sound level.

One difficulty in the use of a weighted sound level is that psychoacoustic judgment data indicate that effects of tonal components are sometimes not adequately accounted for by a simple sound level. Some current ratings attempt to correct for tonal components;

*Hertz is the international standard unit of frequency, until recently called cycles per second; it refers to the number of pressure fluctuations per second in the sound wave.

ENVIRONMENTAL NOISE: FW0 - FW1 - FW2 - FW3 - FW4 - FW5 - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - 26 - 27 - 28 - 29 - 30 - 31 - 32 - 33 - 34 - 35 - 36 - 37 - a1 - a2 - a3 - a4 - a5 - a6 - a7 - a8 - a9 - a10 - a11 - a12 - a13 - a14 - a15 - a16 - a17 - a18 - a19 - a20 - a21 - a22 - a23 - a24 - a25 - a26 - b1 - b2 - b3 - b4 - b5 - b6 - b7 - b8 - b9 - b10 - b11 - b12 - c1 - c2 - c3 - c4 - c5 - c6 - c7 - c8 - c9 - c10 - c11 - c12 - c13 - c14 - c15 - c16 - c17 - c18 - c19 - c20 - d1 - d2 - d3 - d4 - d5 - d6 - d7 - d8 - d9 - d10 - d11 - d12 - d13 - d14 - d15 - d16 - d17 - d18 - d19 - d20 - d21 - d22 - d23 - d24 - d25 - d26 - d27 - d28 - d29 - d30 - d31 - d32 - d33 - d34 - d35 - d36 - d37 - d38 - d39 - e1 - e2 - e3 - e4 - e5 - e6 - e7 - f1 - f2 - g1 - g2 - g3 - g4 - g5 - g6 - g7 - g8 - g9 - g10 - g11 - g12 - g13 - g14 - g15

                                                                               

Canarina Algoritmos Numéricos, S.L.

Environmental software solutions

Software para impacto medio ambiental  

38300 LA OROTAVA, ,

Islas Canarias, España

e-mail: contact us

 

 

 

European network on pollution · European Union

Member of MAPO: European network on Marine Pollution.

Project funded by the European Commission

through the 6th Framework Programme for Research and Development

vehicle noise

 

 

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CUSTIC: Noise pollution · CUSTIC - Software solutions - Software advantages - Price - DEMO download

DATA: Input data I - Input data II - Input data III - Input data IV - Input data V - Import and export data - Software commands

ENVIRONMENTAL NOISE: FW0 - FW1 - FW2 - FW3 - FW4 - FW5 - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - 26 - 27 - 28 - 29 - 30 - 31 - 32 - 33 - 34 - 35 - 36 - 37 - a1 - a2 - a3 - a4 - a5 - a6 - a7 - a8 - a9 - a10 - a11 - a12 - a13 - a14 - a15 - a16 - a17 - a18 - a19 - a20 - a21 - a22 - a23 - a24 - a25 - a26 - b1 - b2 - b3 - b4 - b5 - b6 - b7 - b8 - b9 - b10 - b11 - b12 - c1 - c2 - c3 - c4 - c5 - c6 - c7 - c8 - c9 - c10 - c11 - c12 - c13 - c14 - c15 - c16 - c17 - c18 - c19 - c20 - d1 - d2 - d3 - d4 - d5 - d6 - d7 - d8 - d9 - d10 - d11 - d12 - d13 - d14 - d15 - d16 - d17 - d18 - d19 - d20 - d21 - d22 - d23 - d24 - d25 - d26 - d27 - d28 - d29 - d30 - d31 - d32 - d33 - d34 - d35 - d36 - d37 - d38 - d39 - e1 - e2 - e3 - e4 - e5 - e6 - e7 - f1 - f2 - g1 - g2 - g3 - g4 - g5 - g6 - g7 - g8 - g9 - g10 - g11 - g12 - g13 - g14 - g15

ALGORITHMS: Algorithms I - Algorithms II