If you are what is termed a "tongue base snorer", this means that your tongue is dropping to the back of your throat causing an obstruction.
A small "gum shield" device known as a MAD (Mandibular Advancement Device) such as the Tomed SomnoGuard® can gently bring your lower jaw forward and keeps your tongue away from the back of your throat, thus preventing the obstruction. If you can make a snoring noise with your mouth both open and closed try this simple test: stick your tongue out as far as it will go and grip it between your teeth. Now try and make a snoring noise. If the snoring noise is reduced with your tongue in this forward position then you are probably a "tongue base snorer".