Natural screen/fence advice

[Oncewassmith]

I'm really hoping a knowledgeable mumsnetter can help! I have a mad 1 year old german shepherd that I let out into my back garden, this used to be a quiet affair until my neighbours adopted the bravest kittens ever who now like to chill out on the fence - the dog is not keen on this so has started to bark at them, and I desperately don't want to be that neighbour!
So next doors garden is about a foot higher then ours so the fence is already 6 foot our side but lower theirs, so a fixed structure is off the cards.
So, finally getting to the point, I want to make a screening hedge/barrier that will mask the cats to a degree, but also would be great if it could soften the noise of a bark as well. I'm looking so far into bamboos etc but I am a total novice gardener so could really do with advice. How would you create a 7 foot high living screening about 10m in length?

Be careful which bamboo you plant some have rampant roots that can cause havoc if the get into drains or building foundations and will spread easily.
It's better to contain them in planters or troughs.
Have you considered pleached trees like a lime.

I hadn't but that's a great idea and will look beautiful

Not sure if you can get any species that are evergreen for all year round screening. Beech will hold most their leaves though.