The basic audio setup in OS X systems has very few options for customization, and therefore should conform to standards that are used by most applications and audio hardware. However, there may be times when a configuration error or two results in odd problems with your Mac’s audio. These can include static in your audio output, lack of ample volume, inability to change volume, lack of stereo output, or no output at all.
Sometimes simply restarting your Mac is the easiest solution; however, this will interrupt your workflow and may not fix all problems. Alternatively, there are several approaches you can take to reset and re-configure your audio output, and hopefully fix the problem without needing to restart.
- Right-click the “Built-in Output” option in the list of devices.
- Choose “Use this device for output.”
If you have another possible output device, then perform these steps for this device, and then toggle back to your built-in input device. This should have OS X re-read the configuration for the newly-selected device, and hopefully fix any odd problems you may be experiencing with it.
Note that often problems with static and the inability to change volume stem from the use of aggregate and multi-output devices. These are where OS X can create a virtual device out of two or more physical hardware devices, allowing you to play output to all of your devices at once (including AirPlay devices). However, this does increase the possibility of synchronization and sample-rate conversion problems between devices. If you choose to use this option, then be sure you use a local clock source (ie, a built-in device, or one attached by a USB cable), as opposed to an AirPlay or other wireless or networked device.
In addition to the timing source, be sure your aggregate device’s sample rate is set to a format that is compatible with all of your devices. Even though OS X should detect and only show compatible formats, go through your list of devices and ensure they are using a common format, such as 44100.0Hz sampling rate and/or 2-channel 16-bit integer bit depth. Do this for both the aggregate device, as well as the individual devices used in it (expand the device to choose the devices used in it).
If you only have your Mac’s Built-in output device available, then try simply toggling its output format options by selecting it, and then choosing a different sampling rate and channel bit depth. Alternatively you can try creating an aggregate device to switch to, and then switch back from:
- Click the plus button under the device list, and choose Aggregate Device.
- Check the box next to your built-in output to include it in the device.
- Right-click the device and choose the option to use it for output
- Click the minus button under the device list to remove the aggregate, and restore your default device.
In most cases, you will have two audio channels on your Mac for stereo output; however, if you have adjusted your device setup and created aggregate or multi-channel devices, then you may have more than one speaker setup available for your Mac. Therefore, click the “Configure Speakers” button in the lower right of the Audio MIDI Setup utility, and ensure both that Stereo is selected, and that the appropriate channel is assigned to the appropriate speaker (click the speaker button in the schematic to play a test sound through the assigned channel).
Lastly, even though most audio configuration can be done in Audio MIDI Setup, if your Mac is only playing mono output (lack of stereo), then you may have one of Apple’s accessibility-related settings enabled. To check this, go to the Accessibility system preferences and choose the Audio option. In here, ensure the “Play stereo audio as mono” option is unchecked (you can also try toggling it on and then off again).