A high squeal when braking. Wear indicators doing their one job. Pads are due.
Pad wear indicators touching the rotor, glazed pads, or brake dust.
Squeal is the warning stage. Book pads before it becomes grinding and rotors.
Reading about sounds only goes so far. The tuner on our home page listens in your browser and tells you what it hears. The app goes further: it names the exact fault, checks it against your vehicle, and tells you how urgent it is.