El o do est conformado por el canal auditivo, el t mpano, el yunque y la c clea. El canal permite que el sonido alcance el t mpano que es una membrana capaz de oscilar y traspasar el movimiento amplificado por el yunque hasta la cloquea. Esta ltima funciona como un analizador de frecuencias que reporta al celebr la estructura del sonido recepcionado.

image

La c clea tiene la forma de un caracol que se vuelve cada vez mas estrecho. Consta de dos c maras separadas por una membrana que se extienden por todo el largo de la c clea. El sonido penetra por el canal y la membrana entra en resonancia en una profundidad que depende del largo de onda. De esta forma se desglosa la se al en sus componentes seg n la frecuencia.

image

$v_2=fv_1$

El o do humano puede captar sonidos con frecuencias entre 20 Hz y 20 kHz. Dicha capacidad se documenta con el numero de decibeles que se amortigua el sonido por frequencia:

image

De la gr fica se ve que la menor amortiguaci n es entre 200 Hz y 8 kHz.

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 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 $20 \mu Pa$.

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 $9.5 \times 10^{-13} , W/m^2$.

$L=L_0 -40\log_{10}\left(\displaystyle\frac{r}{r_0}\right)$