This is the audio exerpt of ɕː 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 ɕː by pressing the word buttons.
1. Break the airflow by touching your alveolar ridge with the tip of your tongue while raising the center of the tongue so that it almost touches your palate.
2. Push the air through the interruption to produce an audible friction of the air.
3. Relax your vocal cords.
4. Pronounce this sound noticeably longer than normal ones.