If you hear very well and the cat is not underground. But the GPS is really very accurate - if the reception is there.
If the cat is somewhere in the house, the tracking doesn't work for me. Nevertheless, I wouldn't want to do without the device. My cat disappeared for 4 days and I only got him back through a huge portion of luck. Since I've had the tracker, I feel safe - and that's not meant to be surreptitious advertising.
The battery should last longer, always log off after a location and recharge every night.