Broadband noise is reduced in ten steps of six dB
Broadband noise is reduced in fifteen steps of 3 dB
Broadband noise is reduced in twenty steps of 1 dB
Free field speech of constant power
In the first part of this demonstration, we hear broadband noise reduced in steps of 6, 3, and 1 dB in order to obtain a feeling for the decibel scale. In the latter part, a voice is heard at distances of 25, 50, 100, and 200 cm from an omni-directional microphone in an anechoic room. Under these conditions, the sound pressure level decreases about 6 dB each time the distance is doubled. (In a normal room this will not be the case, since considerable sound energy reaches the microphone via reflections from walls, ceiling, floor, and objects within the room.)