HDMI audio truncated


I’m testing BBB with HDMI audio output.

If I play a test sound like

aplay /usr/share/sounds/alsa/Front_Right.wav

Sometimes the sound is truncated, for example I can hear only “right” or “ight”
Sontimes the sound is missing completaly.
In addition youtube videos are without sound.

The strange thing is that if i open PCMANFM and I go to “/usr/share/sounds/alsa” and I play the sound selecting the file with the left mouse button and using aplay GUI, the sound is good!!

The OS loaded is BBB-eMMC-flasher-debian-7.8-lxde-4gb-armhf-2015-03-01-4gb.img

Any suggestion?