Decibels by Jared Rovny, PhD

Name: Decibels
Uploaded: 2016-12-16
Duration: 7 min 40 s
Description: The lecture Decibels by Jared Rovny, PhD is from the course Sound.

About the Lecture

The lecture Decibels by Jared Rovny, PhD is from the course Sound.

Included Quiz Questions

What is the dimension of sound intensity?

Power per area
Energy per area
Force per area
Energy per volume
Power per volume

How many decibels is a sound heard with 100I₀ of intensity?

20 dB
2 dB
100 dB
10 dB
1 dB

Why do we use the decibel scale to classify the intensity of sounds which a human can hear?

The decibel scale is more compatible with our perception of the difference in the loudness of different sounds that we hear as compared to the intensity scale.
Its just a more convenient way of representing intensity.
It is easier to work with logarithms in physical calculation related to sound.
There is not much difference between them and both can be used to classify the loudness of a sound.
Because our ears perceive the frequency of a sound wave logarithmically.

What happens to the energy of a sound as it spreads out in a medium?

The energy spreads out over larger spheres centered at the source, hence there is a reduction in the intensity of the sound. The sound energy is eventually lost to the medium in the form of friction and heat.
The energy spreads out over larger spheres which results in the reduction in the intensity of the sound only.
The energy of the sound is conserved only the intensity drops at larger distances from the source.
As the sound intensity dies out over larger distances from the source it gets transferred to chemical potential energy of the molecules in the medium.
Similar to how energy is transferred from potential to kinetic energy in an oscillating spring, the energy of a sound wave is also transferred between the kinetic and potential energy of the molecules in the medium.