Someone that snores that loudly has a high likelihood of having sleep apnea. It's also been shown that spouses and bed partners can't predict whether someone has sleep apnea. Also you don't have to snore to have significant sleep apnea!
There are many conservative options for snoring. Some work, but most are only temporary. See a sleep specialist to make sure whether or not he has sleep apnea. If he has sleep apnea, then treating it will take care of the snoring. Untreated sleep apnea can lead to hypertension, diabetes, obesity, depression, heart disease, heart attack, or stroke. As Curtis 1960 recommends, dental devices are available over the counter (or over the internet - two products that come to mind are puresleep and somnoguard). Dentists can make better fitting and adjustable models that work better.
There are a number of dental devices you can buy to try and reduce your husband's snoring. Some are advertised on TV and others you get through your dentist. There is also a spray that numbs the back of the throat to reduce snoring. Your husband may have enlarged tonsils, adnoids or a collapsing airway when he sleeps. And, if you can get him to sleep on his side, that would really help.
Is your husband tired during the day? Do you hear his snoring stop for a few seconds and then hear a gasp or sharp intake of air? This could be a sign of apnea. People who have terrible snoring problems very often have sleep apnea. If you have insurance, it might not be a bad idea to request an overnight sleep study just to rule apnea out. In the meantime, talk to your doctor about his snoring. He may have some ideas for you.
Best of luck!
Curt