Q8DQ - University Physics with Modern Physics

Question

Question: (a) Does a sound level of 0 dB mean that there is no

sound? (b) Is there any physical meaning to a sound having a negative

intensity level? If so, what is it? (c) Does a sound intensity of

zero mean that there is no sound? (d) Is there any physical meaning

to a sound having a negative intensity? Why?

Step-by-Step Solution

Answer

The softest sound level that the human can hear is the sound level of 0 dB and the 0 dB sound mean that the reference level and the sound level are same.

Step 1: Write the given data:

The sound level is of 0 dB

Step 2: Determine the formula

Consider the formula for the difference in the sound intensities in decibels as:

\({\bf{\beta  = 10log}}\left( {\frac{{\bf{I}}}{{{{\bf{I}}_{\bf{0}}}}}} \right)\)

Here, the sound intensity level is \(I\) and the reference level is \({I_0}\).

Step 3: Determine if the sound level of 0 dB means there is no sound

Consider the case when the reference sound level and the sound intensity level are exactly same. Then:

\(\begin{array}{l}\beta  = 10\log \left( {\frac{I}{{{I_0}}}} \right)\\\beta  = 10\log \left( 1 \right)\\\beta  = 0\;{\rm{dB}}\end{array}\) 

Therefore, the softest sound level that the human can hear is the sound level of 0 dB and the 0 dB sound mean that the reference level and the sound level are same.