What makes you sound so certain?
3 seconds sound clip from the Psycho (1960) movie soundboard.
You can hear this line at 01:31:47 in the Blu-ray version of the movie.
Quote context
[...]
- Well, if he opens a motel on the new highway in, say, a year...
- What makes you sound so certain?
- Or he felt sorry for me and he was beginning to feel the same way about you.
- I could tell the last time I talked to him on the phone.
[...]