Neighbour's dogs bark all day. Please help.

On mobile so apologies for any formatting errors. Also wall of text warning but there's a tl;dr at the end.

So our neighbour's moved in about a 6-9 months ago and brought in 2 dogs. It's no big deal, we have two big boys (Newf and Aussie) and the vast majority of the people on our street have at least one dog. At first they left the dogs outside a lot on leashes which sucked because they barked a lot but after a nice chat they took them in and didn't just leave them alone all day outside.

While inside they barked a lot when the owners were not home because there's a big corner window and no curtains. We waited patiently for a couple of weeks for them to put something up and when they didn't we let them know that the dogs would sit in the window all day and bark.

They put up sheer brown curtains.

Obviously the dogs continued to bark at anything and everything that passed by. We talked to them again and they said "were not getting rid of our dogs". We would never ask someone to do that. We've rescued both of ours and they both have issues that we work very hard to keep in check so we don't bother our neighbours. For instance, we don't let them outside if the neighbour dogs are out since one of our dogs will bark his face off at them if we do. I just take him out front instead if I see that they're outside. They also used to bark back at these dogs but they've actually become desensitised since there is so much barking so that's a win I guess.

We're at our wits end. The biggest problems are that the dogs start barking and howling at 6:30 am when the people leave and don't stop till the people come home. My husband works shift work and I work from home dealing with complicated audio files so I need to be able to hear things properly which is hard with yowling dogs all day. My office is on the other side of the house and I can still hear them through closed windows, doors, and my headphones. I'm also an insomniac so trying to maintain a regular sleep schedule is a big part of my health and this has completely fucked my routine so I'm going on next to no sleep all day even with my meds. We've also tried earplugs and closing the windows but the dogs are so loud that it bleeds through all of that. I can't even express how loud they are.

We've tried talking to them.

We've tried a sonic egg that's pointed at the window where the dogs bark.

We've suggested kennelling the pups or at the very least moving them to the other side of the house.

None of this has worked and they are unwilling to kennel or block the dogs from free roaming the house.

We will call bylaw about it after we talk to them a final time and hand them a letter outlining what we would like at this point but realistically they aren't going to do anything considering their track record.

Is there anything WE can do to stop these dogs from barking that won't hurt them (or our dogs) and that will allow us to get sleep and live in peace?

TL;DR: Neighbour's won't do anything about incessant barking. Is there anything we can do to safely stop the noise?