This is the audio exerpt of uː spoken within a word. It may sound a little short or unclear, but that's exactly how it's in the real context. For more details, read the below explanation of pronunciation and listen example words that contain uː by pressing the word buttons.
1. Open your mouth for about 10%.
2. Round your lips.
3. Raise the utmost back of your tongue without touching the back palate.
4. Push air from lungs while vibrating vocal cords.
5. Pronounce this sound noticeably longer than normal ones.