Decibel calculator

This simple calculation utility, very often sought by those who work in the acoustic sector, It allows us to notice some peculiarities of physics applied to acoustics.
First of all, he immediately jumps to the eye that the sum of two sources of equal intensity does not equate absolutely double of the sound pressure level. In reality, the sum of two identical levels involves an increase of only 3 dB, whatever it is The value in question: (5 db + 5 db = 8 db; 100 dB + 100 dB = 103 db).
The explanation lies in the fact that when two sources have the same intensity, what in fact doubles is the pressure sound (P) and not the sound pressure level (LP) . And since the LP level is the logarithm in the base ten in the base of the pressure P, an additional factor of 3 decibels jumps out for each doubling of the pressure. The formula is the following:
A further consequence of the fact that the laws of acoustics are governed by logarithms are found when adding Two lvers of sound pressure, one much higher than the other. The result of the investigation is almost identical to the greater term. In fact, it is sufficient that the two addends are discouraged by 10 decibels so that the smallest term become irrelevant for the purpose of the sum.

For the difference of Decibel, the theoretical explanation is the same as above concerning the sum.

This simple calculation utility, very often sought by those who work in the acoustic sector, It allows us to understand the meaning of the Continuous equivalent level weighted laeq .
The equivalent level is the average integrated over time of the sound pressure level. It therefore defines a unique value descriptive of the overall noise. Otherwise, however, the sound pressure level is indicative of noise instant for instant. Therefore the first, as the time of measurement, tends to become constant; the second is constantly change. In the following figure, which shows the time history of a common phonometric measurement, all this can be easily displayed. Time History is a graphic designer that represents the trend of the noise level over time. The line Blue represents the instant sound pressure level, the red line represents the equivalent level.
Suppose we want to characterize the noise of a certain investigation environment. The noise certainly will not always have constantly the same intensity. However, we imagine that in this place there are three very noisy main processes and that follow one another. As seen on the page relating to the sum of sound pressure levels, a much more intense noise than everyone The others present is equivalent to the overall intensity. Therefore it can be deduced that the overall noise of the environment of Investigation is given exclusively first by a process, then from the next and finally from the last processing. If a phonometric detection could not be carried out throughout the working day, some can be measured minutes of each of the three processing phases. We would get three levels of pressure LP1, LP2, LP3. Knowing the duration T1, T2, T3 processing, by means of the following formula (on which the calculation utility above is based), we will get the same result.
A peculiarity of the laws of acoustics, due to the presence of logarithms within the formulas, rediscovers in fact that individual events of high noise, even if of a reduced duration compared to the rest of the measurement time, become deciduous for the purposes of the final value of the equivalent level. In a nutshell, an entire size at low noise levels can Be easily staggered by a single very noisy event, as the equivalent level is significantly affected.

Questa semplice utility di calcolo, molto spesso ricercata da chi opera nel settore dell'acustica, ci permette di convertire i decibel in pressione e viceversa.
Quando si parla di rumore, si pensa direttamente ai decibel, cioè l'unità di misura dell'intensità di un segnale sonoro. In realtà però il decibel non è altro che un artificio tecnico per rappresentare l'intera gamma di suoni (dai più forti ai più deboli) su una scala molto più corta e facilmente memorizzabile. Infatti, il vero indicatore dell'intensità di un suono è la pressione. Del resto, un'sound wave è essenzialmente una variazione della pressione dell'aria ocomunque del mezzo elastico entro cui essa si propaga.

A simple example to understand why this conversion artifice: it is much easier to store a plane It produces 130 dB while the rustle of the 25 dB leaves, instead of memorizing that a plane produces 63.25 PA and the rustle of the leaves 356 & micro; pa. Furthermore, in this way, the measurement field in which the most common sounds fall to which we are used to. With a lighter sound, like the rustle of the leaves, to the stronger sound that we can imagine, like a plane In take -off, on the decibel scale we find only 100 decibels of difference. The totality of the sounds that we can perceive falls at this interval. If, on the other hand, we reasoned in terms of pressure then we would go from 0.000365 to 63.25 Pascal. The interval evidently becomes too extensive and difficult to memorize as a order of magnitude. To all this Obviously the convenience of reasoning is added only with whole numbers.

This simple calculation utility, very often sought by those who work in the acoustic sector, It allows us to calculate how it propagates the noise is a point source in space.
First of all, it is necessary to explain the difference between pressure level lp and power level lw. The level of sound power indicates the intrinsic sound of a source and is a unique value. Otherwise the pressure level sound indicates the sound of a source in the various points of the space for which it depends on the distance. As you move away From the source the level of pressure sound decreases understandably while the sound power level always remains The same because it is an objective characteristic of the source.

This simple calculation utility, very often sought by those who work in the acoustic sector, It allows us to calculate how it propagates the noise is a point source in space.
First of all, it is necessary to explain the difference between pressure level lp and power level lw. The level of Sound Power indicates the intrinsic sound of a source and is a unique value. Otherwise the pressure level sound indicates the sound of a source in the various points of the space for which it depends on the distance. As you move away From the source, the level of Sound pressure decreases understandably while the level of sound power always remains the same because it is an objective characteristic of the source.

The conversion from power level to Pressure Level is very useful when you want to predict the noise produced by a specific equipment at a certain distance starting from the data provided by the manufacturer. Usually, in fact The manufacturer provides the power level of the machinery, calculated in the laboratory with special emission tests sound. In the second calculation utility of this page we notice how, for the purposes of conversion from LW to LP, it is necessary The Directivity Factor Q. It depends on the positioning of the source with respect to the support plans. It is easy to guess how The sound emissiveness of a source is much stronger if it is placed in a corner rather than on a horizontal plane. In the first case, in fact, the slice of space through which the noise can be propagated is much smaller therefore the wave of much more concentrated propagation.
Using the first calculation utility of this page you can easily notice how the pressure level pressure level of one Sound source decreases by 6 decibels at every doubling of the distance. So if an air conditioner emits 66 decibels at 3 meters They will perceive 60 to 6 meters and 54 to 12 meters and so on ...

This simple calculation utility, very often sought by those who work in the acoustic sector, It allows us to convert the frequency to Wavelength and vice versa. The two sizes, in fact, are strictly related to each other. They are inversely proportional and their product is equal to the speed of the characteristic sound of the elastic media of propagation. In the most common case of air, the propagation speed C is equal to 331 meters per second. With this small calculation it is possible to notice how very high frequencies correspond to very low wavelengths and vice versa. Therefore it will be easy to remember that a very acute sound (high frequency) has a wave with a large number of close ranges. On the contrary, a very serious sound (low frequency) has a wave with few and distant oscillations.

This complex calculation utility, very often sought by those who work in the acoustic sector, It allows us to calculate, unless the measuring uncertainty, the level of daily noise exposure starting from Measures relating to each task that composes the job. According to the new UNI 9432: 2011 and 9612: 2011, for each Three measures must be made in order to define as fully possible as possible the characteristic sound level of the various tasks. If the three measures differ by over 3 db are not valid for which new phonometric surveys must be made. The utility does not provide for the calculation of the measuring uncertainty as it depends on numerous factors related to the method of investigation and measurement.