Obtain a digital sound level meter and turn it on. Turn the dial to set the frequency range. If the meter is not displaying a number, turn the range higher until it registers.
Set the response time on either fast or slow. A fast response time is about twice as fast as the slow response time and is the speed that the sound is measured continuously.
Point the antenna on the top of the meter at the sound while holding the bottom of the meter near your ear. This area will give you the most accurate reading for the sound you are testing.
Read the digital display. It will indicate how loud the sound is, measured in decibels.