Est-il possible d'utiliser une trace sonore sans que le volume diminue lors de la rotation de l'image?
Merci

Yes, configure the sound as a Background sound in the Panorama properties - rather than setting a (directional) Sound spot.

Each soundtrack is attached to a Hotspot. Have a look... http://www.360-image.com/360/helico/

If you attach sounds to hotspots then they will be delivered as directional sounds.

I don't feel that it is a problem in your pano/tour;because you don't use autorotation.

You could edit the XML file to change the directional aspect of the sound.

It would be a good to have that option via the GUI too. You may wish to request that feature in later versions.

And what is the variable I could edit in the XML file?

Look for the directional sounds section in the tour-name.xml file - see screenshot and edit according to krpano documentation for the sound player:

http://krpano.com/plugins/soundinterface/

I changed this...
<action name="onclickspotpoint25">playsound3Dwhenpossible(soundspotpoint25, %$videos_sounds_path%/sounds/_6-variometer.mp3,true,84.551404,21.785760false);displayImage( %FIRSTXML%/spots/_06-variometre-500px.jpg

To this...
<action name="onclickspotpoint25">playsound3Dwhenpossible(soundspotpoint25, %$videos_sounds_path%/sounds/_6-variometer.mp3,false,84.551404,21.785760false);displayImage( %FIRSTXML%/spots/_06-variometre-500px.jpg

Sound is now working as expected. Thanks for your help