Point Source Sound

Physics Tutorial

Point Source Sound


The intensity of a sound is the amount of energy that passes through a given area in a given time.

I= E/A*t

This equation can also be expressed in terms of power because power is equal to energy over time.


Sound from a point source will radiate from the source in every direction (spherical) such that the intensity of the sound is equal to:

I= P/4πr^2

Sample Problem

Sound intensity from a point source will decrease as the square of the distance. You stand a certain distance away from a speaker and you hear a certain intensity of sound. If you double your distance from the speaker, what happens to the sound intensity at your new position?


*It drops to 1/4 its original value


For a source of a given power P, the intensity is given by I= P/4πr^2. So if the distance doubles, the intensity must decrease to one-quarter its original value.

About The Author

Suggested Tutors for Physics Help


Varsity Tutors

(855) 475-5132 - Award-Winning Academic & Test Prep Tutors


Study Wizards

(408) 883-8660 5-Star Yelp and Google in-home tutoring


Air Tutors

One-on-One Ivy Tutoring Partners 24/7


Link Educational Institute

Link Educational Institute

Leave a Comment

Your email address will not be published. Required fields are marked *