Phasmophobia is a scary and engaging early access release from Kinetic Games that has players playing as paranormal investigators. Ghosts try to distract or mislead players through a number of methods, including triggering car alarms. This makes it hard to listen to clues or communicate with team members, and can completely derail a ghost hunt. Fortunately, it's not hard to disable these annoying noises.
There are two types of keys in Phasmophobia, the Main Door Key and the Car Key. The former unlocks a building's main doors and can often be found hanging from mounted hooks or resting in a key bowl on small tables near the front of the house. The latter is used to shut off the blaring car alarms that ghosts set off to disorient and distract investigators.
Whenever a car alarm is triggered, the ghost will spawn a Ghost Interaction EMF Level 2 spot within 2m of the vehicle. If you have the car keys, you can simply walk over to the vehicle and interact with it to turn off the car alarm. However, the keys can spawn in random spots, and they don't necessarily always appear at the front of the house. You'll need to look around on the walls and on furniture, especially dressers and tables, for them.
The best way to find the keys is to stand directly next to the offending car, which will usually trigger the alarm to shut off. Alternatively, you can use your EMF detector to see if the ghost is nearby. If the car alarm was turned off quickly, the ghost should still be close by, and a Level Two reading should appear on your EMF reader if it is.