Stereo Polarity (Phase) Sound Test

Background

Depending on how a speaker has been wired internally or connected to the amplifier, it will either move in or out in response to a given input signal. As long as a single speaker is concerned, this direction has no influence on the perceived sound. Our ears are simply not sensitive to the absolute phase (please refer to our Absolute Polarity Blind Test if you don't believe us). However, when using two (or more) speakers, polarity defines how these speakers interact with each other. Speaker polarity then becomes a very important parameter to check.

When polarity is wrong, the speakers will be out of phase. One will move in, while the other moves out. At the listening position (right in between the speakers) the displaced air from one will be cancelled out by the other. This effect - stronger at lower frequencies - will result in a loss of bass. It also drastically distorts the stereo imaging.

The test files

Three files here: a monoral low frequency rumble, a 75 Hz sine tone and a guitar recording, all with their respective "in phase" and "out of phase" variations.

↓	↓	↓	↓	↓	↓
Rumble In Phase	Rumble Out of Phase	75 Hz Tone In Phase	75 Hz Tone Out of Phase	Guitar In Phase	Guitar Out of Phase

From a central listening position, listen to the "in phase" and "out of phase" versions.

If your speakers are correctly set up, the "in phase" versions will

• produce more bass with the low rumble tone
• play louder with the 75 Hz sine tone
• render the guitar recording as if the guitar was playing in front of you - not "inside" your head - with a full body character.

If you experience the opposite, simply flip the connecting wires of one of your speakers (not both!) to correct the problem.

Related pages

Other Stereo Tests

• Left / Right Audio Test
• Stereo Imaging Test

External Links

• Speaker Features and Issues