By how many decibels does the intensity level of a sound increase when you triple the intensity of a source of sound?

a) 3.0 dB
b) 4.8 dB
c) 12 dB
d) 9.5 dB
e) 6.0 dB

Respuesta :

To solve this problem we will apply the concepts related to Sound Intensity. From the expression of decibels, the intensity of the sound defined as acoustic power transferred by a sound wave per unit of normal area to the direction of propagation. Mathematically it can be expressed as,

[tex]\beta = 10log_{10}\frac{I}{I_0}[/tex]

Where,

I = Intensity of sound

I_0 = hearing threshold

If we take these values for the two intensity levels we would have to

[tex]\beta_1 = 10log_{10}\frac{I_1}{I_0}[/tex]

[tex]\beta_2 = 10log_{10}\frac{I_2}{I_0}[/tex]

The total difference between the two intensity would then give us that

[tex]\Delta \beta = \beta_2-\beta_1[/tex]

Since the statement intensity 1 is 3 times greater than intensity 2. Therefore

[tex]I_2 = 3I_1[/tex]

[tex]\Delta \beta = 10log_{10} (\frac{3I_1}{I_1})[/tex]

[tex]\Delta \beta = 10log_{10} (3)[/tex]

[tex]\Delta \beta = 4.8dB[/tex]

Therefore the correct option is B.