Had a similiar problem with some people who lived at the back in the council estate, their gardens back onto ours although having a fairly large garden they were well away say 200 yards hidden behind trees, and we couldn't identify the people concerned. The barking of several dogs was a bloody problem early morning, and constantly from15.30 until late evening. We could not enjoy the garden at all this noise took over everyrthing.
I have two labs, and they stay in the garden and never bark.
A few enquirys, and I discovered they were a problem family and very anti social, abusive, breaking into sheds etc, so best I leave it to the coucill thought I
What a blasted palarver, I had to fill in a diary type form for three weeks detailing when and what problems were caused. The Council then wrote to them asking them to control their animals, with a final visit to tell them verbally that action would be taken against them. Well after all this it was autumn and we didn't go in the garden, until next summer.... you got it, it started all over again, two summers wasted before the council kicked them out for other reasons.
It has been peaceful for the last couple of years
but not by any action to stop this by the coucil I pay tax to.
I would suggest you and as many other neighbours as find it a problem contacti the Enviomental Health, and at the same time a local coucillor to gee them along.
You have my sympathy, it becomes such a problem that you wait for it to happen, and then end up raging with high blood pressure