Speaker test
Check that left is left and right is right, then sweep from deep bass to high treble. Start with the volume low, especially on headphones.
Frequency sweep20 Hz → 20 kHz
Most people hear up to about 15–17 kHz, less with age, so the top of the sweep going quiet is normal. Small laptop speakers can’t play much below 100–200 Hz. Listen for buzzing or rattling on the way up: that’s a loose part or a damaged speaker.