How to keep system alerts loud while music stays quiet on Mac

On a Mac you can't make alerts louder than your overall volume — the Alert volume slider is a percentage of your main output, capped at 100%. So the fix is the reverse: leave system output where alerts sound right, and turn down only the music app. macOS has no built-in per-app volume control, so that last step needs a small mixer. Set the music app low, keep output high, and notifications, Slack pings, and system sounds still cut through while your music plays softly.

This is one of those Mac annoyances that feels like it should have a setting and doesn't. You want background music kept low so it doesn't drown out a podcast or your own thinking — but you still want to hear the doorbell-style stuff: a calendar alert, a Slack mention, the Mail whoosh, an alarm. On macOS those live on the same single output, and the controls Apple gives you move them together.

Why turning the music down also quiets your alerts

Open System Settings → Sound and you'll see two sliders: Alert volume in the middle and Output volume at the bottom. The catch is in how they relate. Per Apple's own documentation, alert volume is relative to your computer's volume — it sets what percentage of the overall output level alerts play at, and that percentage can't go above 100%. In plain terms, alerts can be as loud as everything else or quieter, never louder.

So the obvious move backfires. You drag the system volume down to tame loud music, and your alerts duck right along with it, because they're pegged to that same master level. There is no native switch that says "hold notification sounds at full while everything else gets quiet." The Alert volume slider only lets you make alerts relatively softer, which is the opposite of what you want here.

The reframe that actually solves it

Once you know alerts can't exceed output, the path is clear: stop turning the whole system down. Keep your output level where alerts sound right — full, or wherever you like them — and lower only the one thing that's too loud, the music app. Now the gap you wanted exists: music sits quietly underneath, while alerts and system sounds play at the full output level on top of it.

The problem is that macOS gives you no place to set a single app's volume. The system keys, the menu-bar slider, and the Sound panel all move the master level only. To turn down just Spotify or Apple Music while everything else stays put, you need either the app's own slider or a per-app mixer.

Option 1 — Use the music app's own volume (free)

Most players carry an internal level. Spotify, Apple Music, a browser tab playing YouTube, VLC — each has a slider somewhere. Drop that app to, say, 25% and leave the system output high. Your music is quiet, your alerts are loud, and it cost nothing. For a single fixed music source this is genuinely the right answer.

Where it falls down is everyday reality. Each app hides its slider in a different spot, some sources have no usable internal level at all, and the moment your "quiet" source changes — a different app, a new browser tab, a video that ignores the player's volume — you're hunting again. It's free, but it's manual, and it doesn't stay set across the apps you actually rotate through.

Option 2 — A per-app volume mixer (the reliable fix)

A per-app mixer sits at the audio layer and gives every running app its own level in one place — the thing macOS never shipped. You turn the music app down once, keep system output high, and the balance holds regardless of which app the music comes from. Because alerts and system sounds ride the main output, they stay loud automatically; you're only ever lowering the noisy app, never the alerts.

Several tools do this. They differ less in whether they can set per-app volume and more in how fast you reach the control and what they cost.

Background Music is free and open source, and if you just want a menu-bar list of app sliders it does the job. SoundSource from Rogue Amoeba is the polished, feature-deep option — per-app volume plus EQ and routing — at $49 one-time. Fader is the keyboard-first take at $19.99 one-time. All three keep alerts loud the same way: you only ever lower the music app, never the system output that alerts depend on.

Why the speed of the control matters here

"Keep music quiet" sounds like a set-and-forget job, but in practice you ride it. Music up while you work, down the instant a call starts, back up after. If reaching the control means moving to the menu bar, clicking the icon, finding the row, and dragging a slider, you'll stop bothering and just yank the master down — which is exactly the move that kills your alerts.

That's the gap Fader is built for. You hit a toggle hotkey, the keyboard becomes a mixer, and you ride the music app's level with letter keys without leaving what you're doing — system output never moves, so alerts stay exactly as loud as you set them. If you want the broader picture, see how to lower one app's volume without lowering everything, or the full rundown of controlling individual app volume on a Mac.

A note on Do Not Disturb and Focus

If your real goal is fewer interruptions, not louder ones, that's a different lever — Focus and Do Not Disturb in System Settings let you silence or filter notifications by time, app, or mode. But that's about whether alerts arrive, not how loud they are relative to music. For the loudness balance itself, the output-stays-high, music-stays-low approach above is the one that works.

Bottom line

You can't make Mac alerts louder than your output — alert volume is capped at the main level. So don't fight that; flip it. Keep system output where your alerts sound right and turn down only the music app. An app's own slider does this for free if your music always comes from one place. For a balance that holds across whatever's playing — and that you can ride in a keystroke as calls come and go — a per-app mixer is the fix, and reaching it fast is exactly what Fader is for.