This is a collection of audio tools and test tone videos to optimize your room acoustics and professional audio or hifi system. These are tools to check your audio spectrum frequency response, check the polarity of your monitoring speakers, a 440 hz tone for concert pitch tuning and a chromatic frequency sweep to check for peaks and dips in your frequency curve.
From the casual listener to the audio engineer these audio tools can provide great results.

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Polarity check

With this audio tool you can test if your speakers or headphones are in phase.
The test tone starts 'in phase' then switches to 'out of phase'. The sound should be coming from the center of the stereo image when 'in phase' plays and out of center or like "in your head" when 'out of phase' plays.

When you experience it the other way around your speakers or headphones are out of phase.