It helped me in part with hyperacusis - hypersensitivity to sound. One theory relating to how problems can start is from painful ear infections. Sound causes pain and then the mechanism in the brain that wants to keep track of and avoid pain starts to abnormally develop associating pain with sound - so you can avoid it. ADD/ADHD, depression ... all seems reasonable to stem from this - if you're constantly focusing on sound or attention drawn by sound then you can't concentrate on thought or other, likewise, that prolonged state could lead to depression. There's quite the spectrum of what can come from it, also depending when the developmental delay occurs.
The training/therapy is 10 days over 2 weeks (5 days per week), 2 sessions per day, once in the morning and once in the afternoon, each session being 28 to 33 minutes long - using specially modified oscillating sound based on your audiogram.
The first time I did AIT was in my early 20s. The audiologist I went to, who is also a naturopath and homeopath, set me up across from a ~7 year old boy with his mother. He had the 'zombie' autistic look - no expression on his face, arms fixed by his. His mother would point to the chair and tell him to sit, and he'd go and sit - so he could understand. In the boy's case, I had asked the audiologist - he explained to me that the boy was able to receive input but he was blocked from outputting. What I observed over that initial week, along with the benefit I personally had from doing the sessions, sold me completely on the subtle power and benefit of it. At one point within the first week the boy start saying single words and then a few words together. He wasn't just saying the words though, he was YELLING them. Why? He had never spoken before so he hadn't learned volume control yet. The second week on the Monday he was so excited for the session that he ran into the living room and his seat without taking his shoes off. He sat quietly, with a huge smile on his face, just flipping through a kid's book - I presume reading it.
AIT should be mainstream and helping that happen is part of my life's work - that I at least hope I'll eventually be able to integrate into my plans.
You can actually do an audiogram to check for an imbalance in hearing as a diagnostic tool - it's a good way to verify if someone is likely to benefit from AIT.
Currently audiologists during a hearing test just check to make sure you can hear well-enough. Can you hear at 15 decibels in both ears? Great. It is simple however to check for an imbalance in hearing. You check instead of how LOW of a decibel you can hear in each ear. For example, if in your right ear you can hear the 1000 Hz frequency at 15 dBs and in your left ear you can hear at 12 dBs, then there's an imbalance of 3 dBs. Your brain and body is a system wanting to find homeostasis - so it should correct for this and there shouldn't be a difference. That can tell us that something is going on. In fact, at certain frequencies if there is an imbalance you can accurately predict the behaviour of people -- if there is an imbalance at 1000 Hz then that person will 100% of the time be depressed, medication won't help them, nor will talk therapy -- they are stuck in a fixed state. There are at least a handful of other frequencies that if there's an imbalance showing then there are the predictable behaviours, and that can be used as a guide for talk therapy - along with doing AIT to help the brain become unlocked/malleable again. It's quite fascinating.
There's another sound therapy method called the Tomatis Method. The difference between the two is simple. If the developmental delay or problem occurred while the child was in the mother's womb, then Tomatis method is needed -- it focuses on frequencies that the body/ears/brain hears while in the womb. If it's anytime after birth then AIT is supposedly sufficient. The Tomatis method is a much longer period of time listening - I believe something like a minimum of 3 hours of listening per week over 3 months. There is a book that's out of print that I've never read, though I've been meaning to for a decade now - called Hearing Equals Behaviour - the audiologist told me about it.
The audiologist also had told me to stop eating wheat, as he had seen the progression of what I was dealing with caused by wheat; interestingly enough wheat is linked to childhood ear infections as well - I'm not sure if it's related to that there's an opiate in wheat, however I am very affected by wheat and have avoided it since then.
Here's a provider's website that has a simplified pre-care questionnaire, for both children and for how symptoms present for adults:
For children - http://www.aithelps.com/auditory_care.php
For adults - http://www.aithelps.com/auditory_care_adults.php
I hope this helps fill in some gaps to the vague marketing speak of "strengthens and balances your hearing system" - although apparently it does help the ear muscles flex more properly - I suppose like helping get it out of a spasm state. That seems to be easier for people to grasp as a concept, though you're right it doesn't really explain the value of it.
Feel free to email if you have any questions: matt - at - engn - com