The media's volume represented on a linear scale between 0 and 1. The default is 0.85.
Assembly: Microsoft.Phone (in Microsoft.Phone.dll)
Volume can be difficult to quantify because each media file has a different baseline for its recorded or perceived audio level. Also, true audio volume as represented on the decibel scale is inherently logarithmic. Think of the property as representing the position value of an audio mixer slider control, with 0 being all the way down and 1 being all the way up.
Volume settings may not be retained in background audio player applications. This can occur if you set the property first and then call the Play() method and then set the Track property. To resolve this issue, always set the track before calling the Play method.