Kids do make a noise and often at the most inopportune times =- but usuallay, their parent/s really dont want the hassle either and unlikely to be making noise on purpose - you cant shut a kid up unless he/she eants to shut up sadly, although a suggestion for your neighbours to attend parenting classes may get a hostile response converted flats are usually very bad news noise wise - i got used to mine, but it was only when I got a house did I realise how bad it used to be - and most of the noise isnt designed to personally irk you, its just the way it goes - high turnover of tenents/ owners, rubbish landlording , cheap conversions and lack of proper lease caveats being present or enforced with regard to floor coverings is behind it all. unless you move, sadly it will always be at the back of your mind and you will hear literally everything as time goes on & you become attuned to what once seemed harmless background noises