Panning In Headphones Issue

[SeattleSteve]

Recently finished my home studio, 003R, Command 8, using Presonus Central Station for monitoring control.

Here's the prob.

When setting a pan position while playing a mono track and listening on headphones, I hear a distinct 'jump' in position somewhere around 90-90% hard left or right. Not smooth and linear at all on the outside edges of the pan spectrum. I get this regardless of whether the headphones are plugged into the Central Station front jacks or the 003 phone jacks.

But, when listening to my speakers, I don't hear this 'jump', the panning is smooth and linear. That's good news, of course, indicating that it's likely a headphone phenomenon only. But since I do a lot of late night work on headphones, it's annoying to hear this oddity in the phones.

Anyone else run into this, or have thoughts on an explanation/solution?

Thanks, Steve

[Roey]

Hi Steve,

What you are experiencing is very normal and not part of the equipment you use - it happens on every system. The reason behind this phenomenon is very interesting:

Helmut Haas, who devised what is known as the Haas effect (or the law of the first wavefront), told us that the ears will localize a sound based on the first wavefront to reach our ears, provided that a similar sound arrives in less than approximately 35ms and is approximately less than 10 dB louder from the first sound.

When listening via speakers, and when the same material is played from both speakers but the right speaker emits approximately 15dB less than the left speaker, the sound coming from the left speaker masks the sound arriving from the right speaker and, per Haas, we localize the sound as if coming (nearly) fully from the left speaker. Said another way, around 15 dB of attenuation on one speaker is sufficient to fully shift the image to the opposite speaker, with any further attenuation hardly or not affecting the image localization.

With headphones, however, the left can does not mask the right can, so further attenuation is needed (something around 60 dB) in order to shift the image fully to the left.

The design of pan pots is fully oriented towards speaker-based monitoring and not headphones. The way localization is achieved with headphones is a different science.

You can make the following experiment:
Create a new Pro Tools session, create 2 mono tracks, pan each to a different extreme of the panorama and import the same mono file to both tracks. Now attenuate one track by 15 dB. When listening via speakers you'd hear that the image appears fully to one side. If you then put your headphones on you'd hear that the image appears only slightly off-centre.

Regardless of your circumstances, I wouldn't make any spatial decisions when mixing with headphone - unless, of course, you are mixing an online edit (iTunes etc.).

Hope this helps,

[SeattleSteve]

What a great explanation, Roey. I've been a professional engineer for over 20 years and not once have I ever run into this phenomenon, but then again I've spent almost 100% of my career monitoring over speakers. It's only been since I finally built a home studio and started using headphones at night that I've experienced this. Good to know it's not the gear, or my wiring in and out of my patchbay.

Thanks and most sincerely,

Steve Heinke
Seattle

[Roey]

Glad to help,

You might want to check out this article: Mixing On Headphones (SoundOnSound)