Hmm... Hmm... Sounds like old Toswer.
7 seconds sound clip from the 101 Dalmatians (1961) movie soundboard.
You can hear this line at 00:37:44 in the Blu-ray version of the movie.
Quote context
[...]
- It be up to me to reach the Colonel! He be the only one in barking range.
- You'll never reach him at this hour!
- Well, I can try! I'll bark all night if I have to.
- Hmm... Hmm... Sounds like old Toswer.
- Sergeant! Sergeant Tibs! I say, Sergeant!
- Barking signal. It's an alert. Report to the Colonel at once.
[...]