If you are trying to hear sound during your RAM preview playback, click the arrow in top right (default) where you see the sound settings.
Be sure the clip has sound and be sure the eye is turned on. To verify it has sound, click the clip and then "L L" to reveal the wave form below that clip.
Thanks for your answer
I've tried what you said but It doesn's work
I check clip has sound and the eye is turned on and also check the wave
the wave is exist but no sound
Can we please see some screenshots from the two audio preferences screens?
Are you still facing this problem? If not, let us know how you solved it. If so, please let us know so we can assist you further.
If you press "0" on the numeric keypad it should playback with sound. If you press "." on the numeric keypad it should play only the sound. Also, if you hold down "Ctrl" key and drag the cursor, it should scrub through the audio. Here's a quick tutorial on how to do it, if you're still facing issues:
Hope this helps