The Bible opens with a creation story in which God speaks and creation happens. ("Let there be light." And there was light.) Later, it tells us, "In the beginning was the Word." What's more, spiritual traditions from across the world believe in the creative power of sound in one form or another. And today, scientists have shown incredible powers of sound -- levitating; changing the state of matter; altering the expression of genes; and more.
So there's no question in my mind that sound can be therapeutic, and as with any kind of legitimate quantum healing theory, it is the application that determines whether a therapy works. So I won't suggest that any old sound therapy is going to be beneficial for you, and don't have proof for you here about any particular brand.
Instead, I'll comment on the goal of sound therapy and mention my experience with one brand.
As with any sort of quantum healing, the goal of sound therapy is essentially to organize the fields that, in turn, instruct the operation of your body. Of course this intertwines with emotional and mental well-being too. You could really take two approaches to this: have a standard sound sequence to offer a standard optimizing process for everyone; or assess the individual in some way and offer personalized sound feedback for them. Since this isn't MUSIC, but SOUND, personal feedback can be generated by a computer without the worry that the song won't sound right.
You could also say that the equipment providing the sound will impact the effectiveness. Some units just have you wear headphones and receive the sound through your ears; I prefer those that provide the therapy to the whole body, as I believe the therapy comes form interacting with the entire field.
It is my OPINION from experience that at least the system I used -- the VAHS system -- has a very direct and profound impact on emotional balance and in fact consciousness itself. This system takes a voice sample and analyzes more than a billion bits of information through a computer; it then plays through a substantial sound tube for the entire body field and also interacts with the field through inert noble gases. When I'm smart enough to use this system on a regular basis, I not only enjoy deeply relaxing sessions that I come out of with a delicious "body vibe," but I find that I am more aware of my responses to the world around me and can more consciously choose what I do, rather than just reacting. Anyone who understands how reactive we are from programming of every sort can appreciate the power this offers you.
I have heard of physical improvements from people using sound therapy, but from my experience and from what I've heard, this is not the primary expectation. Emotional and conscious transformation, however, are more important in my estimation anyway, but everyone has their own priorities, and I think other forms of therapy may offer more physical results.
My only caution with sound therapy is that some systems include glasses with flashing lights, and I'm concerned that someone with a propensity for seizures could run into problems.