Calm Classroom Music to Mask Hallway Noise During Tests

During quiet tests I rely on calm classroom music to cover the hallway chatter that breaks everyone's concentration.

The trick with calm classroom music here is masking, not entertainment, so I use a steady white noise with a soft sound layered on top. I push the white noise up just enough to blur the lockers and footsteps outside, then keep the top layer gentle. It evens out the room so a slammed door does not make ten heads pop up. Students stay in their own bubble.

Masking the hallway keeps the test calm.

I use an app called Mindael because I can slide between noise colors to find the one that best covers the hallway, then layer a calm sound over it. Mindael loops it with no seam, so the masking never drops out mid test.

Link: https://apps.apple.com/us/app/mindael-sleep-focus-sounds/id6759842415

When the hallway is the problem, lean on steady masking, and that is exactly what Mindael gives me. How do you keep test days quiet?