Sound propagates and interacts with various edges and objects. On flat surfaces it is reflected under the same angle it affects (ground, building). However, the wind leads to refraction with what the beams bend:

image

For a point source, the sound spreads in all directions uniformly. Therefore, the sound level will be reduced due to the effect that the energy is distributed over a surface of a sphere of radius r equal to the path traveled

image

Si consideramos una fuente puntual, la intensidad del sonido es con

equation=3193

se propagara en forma esf rica. En este caso la superficie es con

equation=4731

con lo que la intensidad es con

equation=3402

Si se considera una esfera en torno de la fuente a un radio r_0 la potencia W sera igual a

$W=4\pi r_0^2 I_0$

por lo que la intensidad es con list=3402

a una distancia r tendr con list la magnitud:

Since the different beams do not interact, the intensity and power that occurs at any point in space is equal to the sum of the individual contributions:

image

Como los distintos haces no interactuan la intensidad que se da en cualquier punto del espacio es igual a la suma de las contribuciones individuales.

Con list la intensidad total es

model

Si consideramos una fuente puntual, la intensidad del sonido es con list=3193

se propagara en forma esf rica. En este caso la superficie es con list=4731

con lo que la intensidad es con list

Si se considera una esfera en torno de la fuente a un radio r_0 la potencia W sera igual a

$W=4\pi r_0^2 I_0$

por lo que la intensidad es con list=3402

a una distancia r tendr con list la magnitud:

Just like in other human sensory systems, our hearing is capable of detecting pressure variations over a wide range $(10^{-5}-10^2 Pa)$. However, when we perceive a signal doubling, it doesn't correspond to double the pressure or sound intensity, but rather the square of these magnitudes. In other words, our signal detection capacity operates on a logarithmic and nonlinear scale.

Hence, the noise level ($L$) is indicated not in the sound Intensity ($I$) or the reference intensity ($I_{ref}$), but in the base ten logarithm of these magnitudes. Particularly, we take the lowest sound intensity we can perceive, the reference intensity ($I_{ref}$)

, and use it as a reference. The new scale is defined with list as follows:

The sound pressure level that we can detect with our ear, denoted as the reference pressure, water ($p_{ref}$), is $2 \times 10^{-5} , Pa$.

Since the sound Intensity ($I$) is associated with the sound pressure ($p_s$), the mean density ($\rho$), and the speed of sound ($c$), and is equal to

equation=3405

we can calculate a value for the reference intensity ($I_{ref}$) based on the value of the reference pressure, water ($p_{ref}$):

kyon

This is achieved with a density of $1.27 , kg/m^3$ and a sound speed of $331 , m/s$, equivalent to $9.5 \times 10^{-13} , W/m^2$.

The noise level ($L$) encompasses a wide range of the sound pressure ($p_s$), making it useful to define a scale that mitigates this difficulty. To do so, we can work with the logarithm of the pressure normalized by a value corresponding to zero on this scale. If we take the minimum pressure that a person can detect, defined as the reference pressure ($p_{ref}$), we can define a scale using:

kyon

which starts at 0 for the audible range. In the case of air, the reference pressure ($p_{ref}$) is $20 \mu Pa$.