Most noise complaints in flats are about impact, not voices

The theory of noise in flats is well covered elsewhere. This is about the version you meet in practice.

Two different kinds of sound

Airborne noise — speech, television, music — travels as pressure waves through air and passes through any gap it can find. Impact noise — footsteps, dropped objects, dragged chairs — is created directly in the structure and travels through it as vibration.

They need opposite treatments, which is why people who add mass to a wall are surprised that footsteps upstairs are unchanged. Identifying which one you have is the first step and it is usually obvious once you know the distinction.

Airborne noise leaks through gaps

Sound follows air, so the weak points are gaps around service penetrations, back-to-back sockets, loft hatches, gaps under doors and where a floor meets a wall. Sealing those gaps with appropriate acoustic sealant is disproportionately effective compared with the effort.

Adding mass — a second layer of dense board on resilient bars, or a heavy bookcase against a party wall — reduces what remains. A wall improved from one side only helps less than expected if the sound is also flanking through the floor and ceiling.

Impact noise is best fixed at the source

Vibration entering a floor spreads through the structure, so treating the ceiling below catches only part of it and loses head height doing so. A carpet with good underlay on the floor above removes most footfall noise at source and costs a fraction of any ceiling treatment. Acoustic underlay beneath a hard floor is the alternative and is frequently required by leases in apartment buildings.

Room to room, this is why the polite and effective conversation with an upstairs neighbour is about their floor rather than about their behaviour.

What soft furnishings actually do

Rugs, curtains and upholstery absorb sound within your own room, shortening reverberation and making speech clearer and the room calmer. They do very little to stop sound coming in from another dwelling, because they have almost no mass. This distinction is consistently blurred by acoustic products marketed to homeowners.

It is still worth doing, because a less reverberant room makes intrusive noise less noticeable even when the level is unchanged.

Masking is a legitimate strategy

A low continuous broadband sound — a fan, a purpose-made masking device, or even ventilation — raises the background level so intermittent noises stand out less. This works because annoyance depends on the contrast between the noise and the background, not just on the noise. It is far cheaper than construction and is often the only realistic option for a tenant.

In practice, it is a coping measure rather than a fix, and it is honest to describe it that way.

Anything structural belongs with a qualified professional, not an article.

Where it stops being a building problem

Persistent noise that is unreasonable in time or level is a nuisance matter, and most countries have a process through the local authority or the building management. Leases in apartment buildings frequently contain floor covering obligations that can be enforced. Keeping a factual log of dates and times is what makes any of those routes work.

Room to room, structural alterations to improve sound insulation in a flat usually need freeholder or management consent, so check before commissioning anything.

The takeaway

Work out whether it is airborne or impact, seal the gaps for the first, and put carpet on the floor above for the second.

Buy slowly. The gaps are not a problem.