Recently spoke with someone in another part of Calgary who is experiencing a similar noise problem as we are. In fact, they moved from one house to another, only to discover that the noise is in their new house, too.
They've done some investigative work, too, and have learned some interesting things: in their house, the EMF levels are considerably higher than normal. This was, in fact, confirmed for them by Enmax. Unfortunately, Enmax has taken no definitive steps to address the problem.
A suggestion has been made that the noise is caused by power installation going in "too fast" to match our growing city. That's not in my field of expertise, but comments and feedback would be most welcome.
More info to be posted, soon.