I've found this issue and various discussions online about this, but no obvious "just do this", so I'm wandering over here from ServerFault to ask this.

Is there a way to disable or hard-set the input level on a mic? In the Sound preferences on the Input tab if I click on the device and set a level and then start talking it picks up the sound and then start to auto-adjust the mic input level.

This causes issues when talking with someone on Lync/Skype/etc because one minute the sound is fine and then if you raise your voice for a second and then lower it back down (or shift around in your chair) the auto-adjust causes the other party to think your whispering or yelling.

I'd like to be able to disable the auto-adjust if possible. Yes/No?

NOTE: The issue is similar this one: iMac OSX 10.8.4 Volume adjusts by itself but rather on the input side and not the output side for me.

up vote 4 down vote accepted

You can set it via the command line:

osascript -e "set volume input volume 100"

I have found that OSX Polycom RealPresence Desktop has a similar annoying "feature" that adjusts the mic input volume down, but never back up. My workaround is to have this line in my crontab:

# Check every minute for mic input < 100%; if it is, dial it up elegantly
* * * * * while (( `osascript -e "input volume of (get volume settings)"` < 100 )); do osascript -e "set volume input volume (input volume of (get volume settings) + 3)"; sleep 0.1; done;

The loops just makes the slider "slide" up over a second or so, rather then a hard volume jump.

Turns out that the auto-adjusting mic level was not MacOS, but rather Skype (Version 6.6.0.467). There is a check box in Skype Preferences to enable/disable it, and once I turned it off the level stays where I set it.

The problem is that, apparently, Skype's notion of auto adjusting the mic volume is simply to crank it up to max, no matter what -- even when no call is active. At around 90% the mic starts picking up background noise, probably the Mac disk or fan, and by 100% that background noise is overwhelming.

I found that on my MacBook Pro (c. 2008) the mic level at about 75% was good, and I also found it helpful to check the "Use ambient noise reduction" check box (just below the mic level slider in the System Preferences/Audio).

  • That was the issue for me as well. The odd thing was that I was using GoToMeeting at time. This seems to happen in the background whether you're on a call or not. – sholsinger Nov 17 '14 at 19:54
  • This was happening w/ Zoom as well. Once I cleared the flag it was fine and stayed in one spot. – N1tr0 May 18 '16 at 21:07

Found the file for Google Talk/Hangouts in ~/Library/Preferences/com.google.GoogleTalkPluginD.plist.

Edit the file with a preference editor (Xcode, TextWrangler, Pref Setter, etc.) and change the audio-flags setting to 0.

Seems to be a per-application setting.

I just tried this out on my 2011 Mac with OS X 10.8.4 and it worked. It's been driving me crazy for 2 years.

Skype has a Microphone adjustment in Preference Audio Video.

There you can disable the Auto setting.

I do not know about Lync.

  • Nothing like that in Lync and Skype isn't installed. Problem is that it affects not only the input mic on the mac but also Parallels. I keep thinking it is an OS setting, but nothing definitive yet. – TheCleaner Aug 2 '13 at 18:11
  • We are talking about the build in mic ? – Buscar웃 Aug 2 '13 at 18:34
  • It's a Mac Pro...so no built-in mic (except line in)...it's the external Apple monitor with a bult-in Mic (shows up on Sounds as External Mic USB) – TheCleaner Aug 2 '13 at 18:37

I figured it out! I called Mac support and they had me start my computer while pressing Cmd + Opt + P + R and it resets some things that fixes the problem. Hope this works for everyone like it did for me!

MacOS itself doesn't have auto-adjust option for mic, so there applications which are doing this. You need to check, which applications, which potentially are working with camera/mic have this auto-adjust option and to turn it off.

I found that it's some glitch in Skype, which appears from time to time. To disable automatic gain control for mic in Skype you need:

  • Click Tools at the top of Skype window
  • Select Options
  • select Audio Settings
  • Under Microphone, uncheck Automatically adjust Microphone settings

There's also the option to disable it manually in the config:

  1. Quit all the instances of Skype
  2. Go to skype directory, or in terminal execute the command:

    $ cd ~/Library/Application\ Support/Skype/

  3. Open the file called shared.xml for editing, full path to the file is

    ~/Library/Application\ Support/Skype/shared.xml

  4. Search for the line <VoiceEng> and extend that file like this:

    <VoiceEng> <AGC>0</AGC> ... </VoiceEng>

    there could be some extra lines like <MicVolume.., etc, leave them there, no changes. AGC set to 0 means OFF, 1 means ON for automatic gain control, which changes the volume.

  5. Save the shared.xml file, exit, restart Skype. Enjoy!

For me the problem application is Citrix GoToMeeting, which I have to use for work. I'm using a variation of @thetoolman's solution to lower the volume to 49 - 50 every second (no cron job, I just start this whenever I have a meeting):

while true ; do
    while (( `osascript -e "input volume of (get volume settings)"` > 50 )); do
        osascript -e "set volume input volume (input volume of (get volume settings) - 2)";
        sleep 0.01;
    done;
    sleep 1;
done; 

I think I've found the work-around for macOS. You can create an “Aggregate Device”, which works with a single mic (but won’t help with multiple input sources) The Aggregate Device doesn't have its own volume setting, so GoTo can't mess with it.

Open “Audio MIDI Setup”. You can quickly find this by hitting Command+Space, then type in MIDI. Add “Aggregate Device”. In the left column at the bottom, hit the + sign and "Create Aggregate Device" Click on the new Aggregate Device in the left column, and check 'Use' for your microphone in the right-hand panel.

Now the Aggregate Device should be avialable as an input in GoTo. You can still set the sensitivity of the microphone within the Aggregate Device as you normally do, and GoTo can't affect it anymore because it is hidden in the Aggregate Device.

This won't work with multiple Mics in GoTo; GoTo only uses the first channel, so the additional channels are ignored. Rogue Amoeba Loopback can get around this by creating an aggregate device that only has a single channel, regardless of the number of inputs. It is really slick, and easier to use than Audio MIDI Setup, but costs $99.

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