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By Dan Moren

The mystery of OS X’s haunted input volume slider

Usually I prefer to post my head-scratching technical mysteries after I find an answer for them, but on this one I’m stumped—and I’ve been so for some time now.

I’m on a lot of podcasts, and while I’m no audio engineer, I do pride myself on recording decent sound. My Yeti USB mic may not be the top of the heap, but with a shock mount, pop filter, and boom arm, it serves me quite ably on the hardware end.

But it’s the software that’s been confounding me. I’ve taken to recording most podcasts with OS X’s Sound preference pane open, because for some reason, OS X—or one of the apps I’m using (more on that in a bit)—has taken to automatically adjusting my audio input level as I’m recording. Like this:

Audio Input Pane

(That GIF is a slightly sped up version of a chunk of today’s Clockwise podcast.)

I have to assume that it’s intended as a helpful feature: correcting your audio so that it doesn’t get too loud or too soft. But I already have hardware gain control on my microphone set to the level I like. Moreover, sometimes this auto-adjusting phantom seems to act according to its own nonsensical rationale.

It’s unclear to me just how much effect it has on the recording itself. Jason, who edits many of the podcasts I’m on, says that it isn’t pronounced, but I’ve recently noticed a couple blips during shows that I’m editing which I suspect can be attributed to it.

The other problem is that the input level fluctuations affect how I’m hearing myself through my headphones, which are plugged into the Yeti’s monitor port. When the input level drops, I have a harder time hearing myself; when it goes up, I sound too loud. So of course, I innately try to compensate, talking louder when I can’t hear myself. As if that wasn’t distracting enough, I inevitably end up trying to fiddle with the input level as I’m recording.

I’ve spent a long time investigating this phenomenon, which has been around for at least a few versions of OS X, and other friends have told me they notice the same thing.

Casting around online has found a variety of likewise frustrated people, but no solution. Some lay it at the feet of Skype, which does have an auto-adjustment option in its preferences—but I’ve had that unchecked for ages.

And the problem’s not limited to when Skype is running, either: I’ve also noticed it while doing shows via Google Hangouts. (I’ve tried some fiddling with my browser there to turn off any auto-adjusting that may be done by the Hangouts plugin, to similarly no avail.) Hence my conclusion is that something in OS X itself is adjusting the volume.

Though it seems to come and go at times, what I’ve noticed in recent weeks as I’ve been paying closer attention is that the problem only seems to rear its head in Skype on calls with more than two people. When Jason and I record the Six Colors subscriber podcast, for example, the input slider stays where I put it. It doesn’t seem to be until a multiparty call that it goes nuts. Weird, right? (Update: Not longer after I wrote this post, we recorded this week’s episode and, sure enough, I still had the phantom slider doing its thing. So much for that theory!)

And so, my quest for a good solution continues. Whether it’s disabling some aspect of OS X’s audio system that’s doing this (presumably to “help” record better sound) or finding an app that will let me lock input volume into place, I shall not rest until I banish this poltergeist back into the netherworlds from whence it came.

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[Dan Moren is a tech writer, novelist, podcaster, and the Official Dan of Six Colors. You can email him at dan@sixcolors.com or find him on Twitter at @dmoren.]