Reducing low end output.

[Pharos]

I think you need as others have said, to assess the situation and politely ask if your music is, audible or a nuisance, ideally by setting levels in your home and seeing what it is like for your neighbours. This is a considerate stance.

If it is travelling through the floor, heavy carpet or rugs may be of help.

[Pigmy Pony]

I don't see rugs/carpets being very effective, they would be more effective at soaking up the higher frequencies. Whereas bass is no respecter of walls and floors, regardless of room treatment. The only effective remedy for that would be an added layer to what you have, with an insulated cavity. Effectively a 'room within a room', but obviously out of the question in a rented property.

Decoupling the speakers from the floor as much as is possible may be your best solution.

[Primalsea]

As a test you could try plugging the ports quite tightly with socks or t-shirts and see if this works better than the foam.

[Pharos]

I meant as a 'panel damper' as in loudspeaker panels, the panel being the floor, but if it is concrete then a larger mass of damper would be required really.

It seems to me to be unlikely that the bass is air transmitted.

[Sherwood]

I meant as a 'panel damper' as in loudspeaker panels, the panel being the floor, but if it is concrete then a larger mass of damper would be required really.

It seems to me to be unlikely that the bass is air transmitted.

Surely the majority of bass energy emanating from a speaker is "airborne" (i.e. a soundwave).

Cabinet borne energy is likely to be concentrated in a narrower frequency band and may excite particular room resonances. Unless there is a major problem with the speaker design and construction these resonances are surely outweighed by airborne energy.

[Pharos]

It is difficult to see how the sound can travel to other flats if airborne rather than mechanically transmitted or conducted.

[Sherwood]

It is difficult to see how the sound can travel to other flats if airborne rather than mechanically transmitted or conducted.

When the bass energy from the driver units reaches the room boundaries, then a proportion of that energy is absorbed by that surface. This is turn is transmitted outside of the room. The walls effectively become "sound panels"

I am fortunate enough to live in a detached house and to have one room as a dedicated music room. Even when playing music quite loud, the "leakage" is far greater to adjacent rooms than it is to the room below despite the fact that my speakers are floor standing units.

[Macca]

Low frequencies will transmit through the wall or floor more easily because they have a longer wave length so travel a shorter distance in and spend less time inside the wall.

[AJSki2fly]

Hello Rich

If the floors are solid re-enforced concrete then sound transmission through it is not likely to be much at all. Unless the floor had a resonant frequency in the normal hearing range not much is likely to get through. Obviously the thicker it is then the more it will dampen noise. Depending on how old the apartments are the it is also likely there will be some form of heat insulation directly under flooring before you hit concrete, this will also sound deaden further.

One thing you could try is to put some music on with a reasonable low end content and set the volume to an average of 80dB, you can get a free sound pressure meter for you mobile phone to measure it. Then pop down stairs and stand outside the flat below you and see if you can hear much if anything. You could do the same with the flat above, and outside yours.

80dB is a reasonable average listening level, much above this and you are entering into hearing damage areas after 2-3 hours listening. If you know your neighbours you could ask them, but this might provoke an issue when there really isn’t one.

One issue I am very aware of in blocks of flats is that service ducts with cable and pipes running up and down the build can act as sound transmission tunnels. In the 70’s I was in a 17 storey hall of residence in London that had this issue and it was appalling for noise, you could here muffled conversations from rooms many floors below, and if someone had music play it sound like a poor radio in your room. This issue I believe is generally avoided in more modern buildings.

I would check things out before over reacting, and if you have not had complaints then maybe all is ok anyway.

[Pharos]

"When the bass energy from the driver units reaches the room boundaries, then a proportion of that energy is absorbed by that surface. This is turn is transmitted outside of the room. The walls effectively become "sound panels""

That is entirely consistent with my thinking that the sound is transmitted via the substrate rather than through air to another flat.