Audio MIDI Setup on Mac: What It Is and How to Use It

What Audio MIDI Setup is

Audio MIDI Setup is a built-in macOS utility for configuring audio input and output devices connected to your Mac. It shows the audio interfaces, microphones, speakers, and MIDI devices that macOS recognizes, and it lets you change settings such as sample rate, channel configuration, and volume balance. The app is mainly useful when you need more control than the standard sound settings in System Settings offer, or when a webcam, USB microphone, or audio interface needs a specific configuration to work correctly.

How to open Audio MIDI Setup

• Open Finder, choose Go, and then choose Utilities. Double-click Audio MIDI Setup.
• Or use Spotlight: press Command-Space, type Audio MIDI Setup, and press Return.

When the app opens, you see the Audio Devices window. Each connected input or output device appears in the sidebar. If you do not see your webcam microphone, USB microphone, or audio interface, disconnect and reconnect it, then check that it appears in the sidebar.

Choose an input device for your microphone

• Select the microphone or webcam audio device in the sidebar.
• Click the Input tab if it is available.
• Confirm that the device shows an input section with channels and controls.

A connected microphone must appear here before apps can use it. If a microphone is missing, the problem may be a cable connection, power, a driver, or the device not being supported by macOS. The absence of a device in Audio MIDI Setup is not the same as an app permission issue; permission is handled separately in System Settings under Privacy and Security and Microphone.

Check or change the sample rate and format

The sample rate controls how many audio samples per second macOS records or plays. A common rate is 44,100 Hz, but many video applications and webcams use 48,000 Hz. If audio drifts out of sync with video, or an app reports a sample rate conflict, matching the device and app to the same rate can help.

• Select the device in the sidebar.
• Use the Format menu to choose the sample rate and bit depth.
• Retest the audio in the app that was having trouble.

A mismatch does not always cause a problem, because macOS and many apps can handle format conversion. The format setting in Audio MIDI Setup is most relevant with professional audio interfaces and devices that require a fixed clock rate.

Control input and output levels

Select a device and look for available input or output level controls. If the device exposes controls, you can adjust the input level for a microphone or the volume for an output device. Some devices do not expose adjustable controls in Audio MIDI Setup, and in that case their level must be changed in the device's own software, in System Settings, or in the app using the microphone.

If a microphone is detected but records no sound or very quiet sound, confirm that the correct input device is selected in the app doing the recording. Device detection, microphone permission, and active input selection are separate steps. A microphone can appear in Audio MIDI Setup and still not be selected as the active input in a browser or recording app.

Create an aggregate or multi-output device

An aggregate device combines several audio devices into one virtual device. A multi-output device sends the same audio to more than one output at the same time. These options are available from the plus button at the bottom of the Audio Devices window. They are usually used when a single app must handle multiple interfaces simultaneously, rather than for everyday webcam microphone selection.

When you create an aggregate device, it appears in the sidebar like another audio device. You can then select it as an input or output in apps that support a custom device choice. Keep in mind that combining devices can introduce clock drift, and the included devices should normally share the same sample rate.

What Audio MIDI Setup does not control

Audio MIDI Setup does not grant microphone or camera access to apps. It also does not select the default microphone used by every app. Default input and output selection is done through System Settings in the Sound section, while app-level selection happens inside the individual app or browser. If a webcam's microphone is visible in Audio MIDI Setup but not available in a browser, check the browser's site permissions and the active input selection, then reload the page.

The available features in Audio MIDI Setup can vary slightly by macOS version and connected hardware. The general workflow of opening the app, selecting a device, checking that it is present, and adjusting its format is the same across current supported macOS releases.