If you’re able to hear your audio on some devices, such as headphones, but not others, it’s likely that your audio signal has a phase issue. This can often sound like audio that is missing, very quiet, or “hollow.” Phase issues are typically caused by a problem in your signal path, and can usually be resolved with minor adjustments.
What Is Audio Phase?
Audio phase refers to the relationship between two sound waves. Channels are “in phase” when their peaks and troughs are aligned. They are “out of phase” when they are not aligned. In many cases, a channel that is the complete inverse (also referred to as 180 degrees out of phase) of another will cancel the second channel out.
This is more or less how sound-canceling headphones work– they emit sound waves that are the exact opposite of sounds coming from your surroundings.
What Causes Audio Phase Issues?
Phase issues are usually a result of equipment being misconfigured, such as:
- A phase switch unknowingly flipped somewhere in the chain (such as on an audio console, a DI box, or a converter).
- A miswired physical connection, such as a repaired XLR cable where pins 2 and 3 are swapped.
Why Does My Audio Sound Different On Different Devices?
In some cases, phase issues can be worse on mono devices. While your audio may sound “hollow” on a stereo device, it might be entirely missing on a mono device. This is because mono devices combine both audio channels into one. When a mono device combines the positive signal from the left channel and negative signal from the right channel, the result can be a zero signal (or silence).
How Do I Resolve An Audio Phase Issue?
In order to resolve a phase issue where the signal is being canceled out, flip the phase of one (not both) of the channels in your signal path. Phase usually can be flipped at your audio console, on a converter box, by physically rewiring the hot and cold pins of an audio cable, or by using a phase inverter (such as the Hosa GXX-195).