DNO cable through party wall - sealing gap for sound reduction

[martinw]

I live in a mid terraced house (ex council)which dates from around 1950. The supply is a TN-S with no loop out (I maybe looped off one of neighbours I don’t know)

The supply cables seem to lie along the bottom of floor void at front of property, with bricks having been removed/left out. This has lead to noise transmission from next door.

What can I do to seal these gaps, I’m a bit concerned that if anything I do adversely affects the cables I could cause big problems. If I were to use a pro which trade ?

 

[Marvo]

What type of cables are they? If they're PVC could you move them easily so the gap could be plastered closed with some sand/cement mix? If they're lead sheathed cables or if there's anything that looks remotely like asbestos wrapping then definately don't try move them.