Lately I've been reading about Central Auditory Processing Disorder. CAPD is often a co morbid condition of autism, ADD, OCD, and more, but it can stand alone. CAPD is diagnosed by an audiologist who utilizes a variety of testing methods. First a hearing test must be conducted. Then the auditory processing testing takes place in a sound-proof booth and includes listening to different words in each ear at the same time, distinguishing between those words as well as between words with slightly different sounds, trying to understand statements while also hearing loud background noise (ex., the sounds of a crowd of people babbling), and more.
Some of the symptoms in children (as listed at http://www.capdtest.com/ ):
Frequently misunderstands oral instructions or questions
Delays in responding to oral instructions or questions
Says "Huh" or "What" frequently
Frequently needs repetition of directions or information
Frequently needs requests repetition
Has problems understanding in background noise
Is easily distracted by background noise
May have problems with phonics or discriminating speech sounds
May have poor expressive or receptive language
May have spelling, reading, and other academic problems
May have behavioral problems
It's possible that an adult who refuses to acknowledge autism or asperger's (and refuses to undergo psychological testing) might be open to being tested by an audiologist for an auditory processing disorder. A diagnosis of CAPD could be very helpful in an NT/AS relationship. Mutual understanding and acknowledgement of an underlying medical condition (especially one which could be contributing to communication problems) would be a step forward in a suffering marriage!