The Hearing Protection Intervention
In recent updates, Apple has integrated aggressive hearing protection features into macOS. Designed to prevent long-term ear damage, the operating system continuously monitors the audio output levels being sent to connected headphones (particularly AirPods). If the system calculates that you have been listening to audio at a high volume for an extended period, it will automatically intervene. You will receive a notification regarding headphone safety, and macOS will forcefully lower the system volume. While well-intentioned for general music consumption, this automatic intervention is incredibly disruptive if you are a professional audio engineer mixing tracks, or if you are using high-impedance studio headphones that require maximum output just to achieve normal listening levels.
Bypassing the Volume Limiter
To retain complete manual control over your audio interface and stop macOS from nanny-state volume adjustments, you must disable the headphone safety protocols within the sound settings.
Click the Apple logo in the top-left corner of your screen and select System Settings. Scroll down the left-hand navigation pane and click on Sound. In the right-hand panel, look near the top for the Headphone Safety section. Here, you will see a toggle switch labelled Reduce Loud Audio. Click this toggle to turn it Off. A warning dialogue may appear asking you to confirm that you wish to disable this health feature. Confirm your choice. Once disabled, macOS will no longer monitor your exposure limits, and your volume slider will remain exactly where you place it, regardless of how loud or how long you listen.