You can check the paid version without any ads at the following address.
https://play.google.com/store/apps/details?id=jaeyoung.kim.grandfatherclock.pro

Do you remember the old grandfather clock?
Now memories of the grandfather clock to find the app.

Features
- Tick tock sound
- Every hour ding sound
- Half hour ding sound

Special thanks to Go-Eun Elizabeth Yi