Soundproofing 1930s semi after neighbour's extension

[JMPS]

Hi

Our neighbours recently had a pretty significant single storey extension built, going out a few metres at the back and wrapping round the side.  With that new space at the rear, they opened it up to include the old back room and kitchen, so they have one large open plan area.  This new open plan area has tiled flooring, and there are very few soft furnishings as they have a long line of bi-folds out to the back, so not really suited to curtains.

Prior to the work being done, we could hear very little indeed from their side - the old back room was smaller, carpeted, and had curtains.  Since the work though, the noise is pretty awful - some of it (for instance furniture being moved and scraping the floor) seems to reverberate around their side, but still comes through as sound rather than shaking, etc.  Just general conversations are incredibly loud too though - we can often make out exactly what is being said at a fairly normal level of conversation, and if they're being louder (having guests around, etc) then it's difficult to even watch TV as the sound from next door overpowers the sound from the TV.

We raised it as an issue after the work was all completed and we realised what it was like, and they installed some slatted wood soundproofing panels to the walls on their side, and although that had an effect to a degree, the noise is still too problematic to put up with.

Has anyone else been in this position and managed to resolve it satisfactorily?  I've looked on loads of sites where people offer all kinds of solutions, but it seems pretty hit and miss.  It often appears that it's pretty much guesswork as to how to resolve things, and a lot of money can be spent without any real improvement. 

Are there specialists out there that can actually pinpoint accurately what the issue is, and then guarantee a fix?

Any help would be greatly appreciated,

JMPS

[Chachi]

Hi JMPS. Take a peek at my post. I have completed 1 box room, under stairs, hall and landing. Apart from the odd muffled impact noise there is literally no sound comming through the wall. Underlay and sound panels 100%. Obviously I will now cover with fireproof platerboard, but even then I am looking at safe alternatives, from fireproof materials, paints,sprays and so on. The only thing I have to remember is not to cover the lightswitch like I did today. What and idiot!