Sound And Noise From A Physical Point Of View

Sound and noise from a physical point of view

Introduction

Sound and noise.

From a physical and noise physical point of view they have the same characteristics that describe them, in effect, both physical phenomena are sound waves that spread as a result of a disturbance in the air.

Developing

A sound is a physical phenomenon that consists of the mechanical alteration of the particles of an elastic medium, produced by a vibration element, which is capable of causing an auditory sensation. The vibrations are transmitted in the middle, usually the air, in the form of sound waveto the brain the neuronal impulses that finally generate the sound sensation.

With respect to the physical or descriptors of sound and noise as a natural phenomenon, it is noteworthy that both have the same parameters, this in the sense that, as indicated above, they have the same nature. The main descriptors of sound or noise are the following:

T = period (measured in seconds).

F = Frequency or number of cycles per second (measured in cycles per second or Hz, f = 1/t). A = amplitude or maximum displacement from the equilibrium position (m).

λ = wavelength (m)

F = Frequency (Hz)

v = speed (m/s)

Three ways to describe a sound wave.

Source: Young & Freedman. University Physics.

Figure 1 shows pressure fluctuation P (x, t) and displacement y (x, t) in a sound wave that spreads in the +x direction.

This figure also shows y (x, t) yp (x, t) for a sine wave at t = 0. Since the wave is spreading in the +x direction, over time the wave patterns of the functions y (x, t) yp (x, t) move to the right with the speed of wave Ω = υ/k. In addition, it shows how individual particles of the wave move at that moment. These particles, on the other hand, simply range in simple harmonic motion.

In short, sound and noise have the same nature. The above is evidenced in the sense that all noise is sound, but not every sound is noise;Then, noise constitutes a special type of sound, that is, noise is a sound with more pronounced characteristics that allow its distinction of sound, although it is still sound.

Differences between sound and noise.

Sound and noise are two concepts that although they are usually taken by synonym, they keep comparative differences, in effect, while the sound keeps harmony between the waves, that is, it is the result of a series of properly accommodated variations in a range or frequency of emission;The noise is lacking in harmony;Then, the sound obeys a certain distinguishable wave pattern, while noise does not obey apparent patterns and constitute an anomaly of the sound waves.

Another form of distinction between sound and noise has to do with the quality of its perception for human sense, in that regard, if the sound wave has a pleasant quality it is called sound;And, if you have an unpleasant quality to the auditory sense, it is considered as noise or roar. With respect to the difference between sound and noise, it is to take into account the following differentiation:

Sound is a disturbance that spreads through a fluid. This disturbance can be due to local changes of P pressure, vibratory speed V, or density ρ. This vibratory wave can be perceived by the human being at frequencies between 20 Hz and 20 kHz. The frequential components that remain below the lower limit are called infrasonids and those that suppurate the upper threshold are called ultrasonic. [… On the other hand the noise is defined] like any unwanted sound that interferes with the signal that you want to perceive.

On the other hand, in the regulation of national environmental quality standards for noise, the differentiation between sound and noise is established in the following terms: sound, it is the energy that is transmitted as air waves in the air or other material means that it canbe perceived by the ear or detected by measuring instruments;And noise, is the unwanted sound that bothers, harms or affects people’s health.

From what is indicated in the preceding paragraphs, the differences between sound and noise have to be seen more with the perception of the wave and its effect on the receptors of said wave. In the painting that continues some differences between sound and noise.

Differences between sound and noise.

Noise sound

1. Sound wave pleasant to the senses. Annoying sound.
2. It consists of harmonic sound waves. Produced by the mixture of sound waves of different frequencies and different amplitudes.
3. The sound is desired, since it is not disturbing, harmful or annoying. Noise is a sound that is not desired, because it is disturbing, harmful or annoying.
4. Sound is a pleasant sensation or physical vibration. Noise is a physical, but unpleasant sensation or vibration.
5. Sound produces well -being in the environment. Noise is one of the environmental problems.
6. The human ear is able to perceive and support sounds corresponding to sound pressure levels between 0 and 120 dB. The noise is above the so -called pain threshold, 120db. At higher noise levels, physical damage such as the eardrum of the eardrum may occur.

Noise pollution.

, Noise pollution, also called sonic pollution or sound pollution refers to excess sound in a certain place, which alters environmental conditions, referring to sound pressure, considered normal in said area.

, Noise pollution is defined as the presence in the environment of noise or vibrations, whatever the acoustic emitter that originates them, which involve discomfort, risk or damage to people, for the development of their activities or for goods of any nature, or that cause significant effects on the environment.

The term acoustic or sound pollution refers to noise (this is understood as all excessive and annoying sound), caused by human activities (traffic, industries, leisure premises, airplanes, ships, among others.) that produces negative effects on the hearing, physical and mental health of living beings. Sound pollution is a term derived from other forms of environmental pollution on air, soil and water;And, it is closely related to noise and not to sounds;That is, it is closely linked to those sounds that have as its emitting focus mainly to human activities that emit sounds or noise above the pain threshold (120db).

In summary, sound pollution has the pollutant element to noise, this consideration as a pollutant responds to the fact that noise is an annoying sound that can produce harmful effects on people, affectations can be physiological and/or psychological. Finally, it is noteworthy that the main causes of noise pollution are those related to human activities such as transport, buildings, public works and industries, among others.

Environmental noise.

, Noise pollution constitutes a public health problem that causes great concern to health agencies, this because it disturbs community activities, interfering with spoken communication, disturbing sleep, rest and relaxation, preventing concentration and learning, in addition to its effects on health, on individual and group human behavior, and for the physical, psychic and social consequences to which it entails. Environmental noise is the indicator that in a given area there is sound or acoustic pollution. Environmental noise and sound or acoustic pollution, are two terms closely linked from each other to such an extent that, by the presence of environmental noise, sound pollution is explained.

, Noise pollution is considered by the population as a very important environmental factor, which mainly affects their quality of life. Urban environmental pollution or environmental noise is a direct consequence of the activities carried out in large cities. The term noise pollution refers to noise when it is considered a pollutant, that is, sound that can produce physiological and psychological effects harmful to a person or group of people.

, Noise or sound pollution, more specifically, its representative indicator, the environmental noise, has harmful effects on human health, and that, the loss of hearing caused by noise is irreversible;indeed:

Exposure to strong sounds, regardless of duration, causes tiredness in auditory sensory cells, which results in a temporary loss of hearing or tinnitus (sensation of buzzing in the ears). A person attending a large -volume performed concert can leave it with a feeling of deafenation or tinnitus. Hearing improves as sensory cells recover. When it comes to very strong sounds or the exposure occurs regularly or prolonged, sensory cells and other structures can be permanently damaged, which causes an irreversible loss of hearing.

In order to mitigate the unpleasant sensation and/or its effects on the ear, the so -called protection programs against environmental noise are developed. These noise protection programs differ in their structuring and content from one country to another. Such differentiation is due to the fact that the legal requirements are not identical in all countries, also the techniques and methods used in the design of the programs, and in addition, the political approaches to which the programs in question respond vary;However, there are common aspects in the work of all those responsible for developing environmental noise mitigation programs, which according to Brüel & Kjær, are the following:

• Plan new developments in residential areas, industrial polygons, highways, airports, etc.
• Attend to the complaints of the citizens, either during the planning process or after.
• Evaluate the conformity/nonconformity of noise sources (industrial plants, attraction parks, airports, highways, railways, etc.) According to regulations and legislation.

conclusion

As noted in the preceding paragraphs, exposure to strong sounds, or noises, regardless of duration, has both biological health effects (causes tiredness in auditory sensory cells, can damage the eardrum, physical tension or physical stress, etc.), as psychological (nervousness, deconcentration, feeling of emotional tension or emotional stress). With respect to the effects of ambient noise in the body, in the table that continues some effects on the ear or sensations due to the sound values of various activities.