When you are giving a presentation, enjoying a movie, or perhaps relaxing with some music, one of the last things you might want is for your computer to issue some error coupled with a startling alert sound. Granted alerts are intended to get your attention, but when too loud they can be exceptionally frustrating. To help prevent this, you have three options for managing alert sounds: relative volume levels, different alert sounds, and alternative output devices.

The alert volume in OS X will maximize at the volume output of your computer, so generally if you want it to be low then simply lower your Mac’s volume; however, there are times when this may not be feasible. For instance, if you are listening to relatively soft music, then you might have your volume turned up to compensate, which of course will result in a loud alert, if sounded. To prevent this, you can set your alert volume to a different level:

1. Open the Sound system preferences.
2. Go to the Sound Effects tab.
3. Adjust the “Alert Volume” slider to a level where it is not so intrusive.

You might also consider using a different alert sound, some of which are less prominent than others. If you have a special non-default sound that you would like to use for your alert, then first ensure it is in a usable format like .aiff or .wav, an then you can add it to OS X’s sound library in one of two ways:

1. Go to Macintosh HD > Library > Sounds and add it to this folder.
2. Go to the Go menu in the Finder and choose Library (hold the Option key to have the Library appear), and then add the sound in a subdirectory called Sounds (create it if it does not exist).

A couple of noteworthy tips here: first, be sure your alert sounds are not too long in duration. These are alerts intended to get your attention, and not intended to be a ringtone. When played, they will play through from beginning to end, as opposed to a cell ring which you can interrupt with a push of a button. Therefore, keep the sound duration under two seconds, and preferably under one second for best results. Secondly, sounds you place in the first mentioned folder above will be available globally to all users, whereas those in the second folder mentioned will only be available to your account. If you are the only user of your system, then either of these folders will do.

A second approach here is especially good for systems being used to present media like slideshows and movies, where even if an alert occurs, you might want to hear it but not have it be broadcast to your audience. To do this, you can set up an alternative device to play back your alert sounds separately from other audio your system plays:

1. Ensure you have a secondary audio output device plugged into your Mac (this can be any USB, Firewire, or Thunderbolt audio device).
2. Go to the Sound Effects tab of the system preferences.
3. Select the secondary device through the drop-down menu under the alert sounds list.
4. Optionally adjust the volume output for the alerts through this device.

Keep in mind that not all devices (such as Airplay devices) can be used to play audio alerts. Therefore, depending on your setup, you might consider switching your main audio device (done in the Output tab of the Sound system preferences) that your system will use for default audio, and then use the internal speakers or headphones for your alerts.