Of all the reasons adults give up on the piano, the one I find saddest is the one that has nothing to do with playing. They live in an apartment, they are convinced they are disturbing somebody, and so they practice less, and later, and more quietly than is useful — and eventually not at all.
Almost none of that is necessary, and most of it can be designed away in an afternoon.
Start by finding out what the rules actually are
Most leases and most local ordinances have quiet hours, and they are usually narrower than people assume — commonly overnight and slightly extended on weekends. The exact wording varies by city and by building, so the useful thing is to read your own lease rather than to trust a general impression, which is almost always more pessimistic than the document.
Outside those hours, practicing an instrument at a reasonable volume is ordinary use of a home. It is not a special indulgence you have to apologize for, and in most buildings it is explicitly allowed.
That does not make you popular by itself. But it does change the question from am I allowed to do this to how do I do this considerately, which is a much better question.
What actually travels through a building
Two different things, and they need different solutions.
Airborne sound is the music itself, going through the air, under the door, through the thin part of the wall. It is the one people expect.
Structure-borne sound is the one that surprises everybody: vibration traveling through the floor and into the building itself. An acoustic piano, and even a digital one on a hard floor, puts energy straight into the structure — and structural sound goes further and through more than airborne sound does. It is why the neighbor two floors down can hear something the neighbor next door cannot.
The practical consequence: a rug under the instrument, and something soft under each leg or under the stand, does more than a curtain on the wall. Getting the instrument off bare floor is the single most effective physical change available to a renter.
Digital instruments and headphones
If you have a digital piano, headphones solve the neighbor problem completely, and for many adults in shared buildings they are the difference between playing and not playing. Use them without guilt.
But there are two things headphones quietly do to your practice, and you should know about both.
They flatter your sound. Close to your ears, everything is present, warm and even. Balance problems — the left hand too loud, the melody buried — are much harder to hear than they are in a room. So take the headphones off at least once a week and play the same passage out loud, if only at low volume, to check what is actually happening.
They encourage playing louder than you think. With headphones on you cannot hear the mechanical noise of your own hands, and it is easy to hammer. Look at your hands occasionally rather than only listening.
One more piece of physical reality: on a digital instrument, the keys themselves make noise. The thump of a weighted action is quiet in your room and clearly audible through a floor. A rug and a mat under the stand handle most of it.
The practice that makes no sound at all
This is the part that most adults have never been told, and it is a much larger share of real practice than anyone expects.
Tap the rhythm on the closed lid, counting out loud. Rhythm is the first thing a listener notices and it does not need pitch to practice. Ten minutes of tapping a passage in time, hands separately and then together, will fix problems that hours of playing did not touch.
Read the score away from the instrument. Go through the music naming intervals — up a step, down a third — and the shape of each phrase. This builds reading, which is a visual skill, and it is silent.
Practice the fingering on a table. The movement of a hand changing position can be learned on any flat surface. So can the thumb passing under.
Play it in your head, slowly, hearing every note. Mental practice is a serious technique used by professionals before performances, and it is genuinely difficult, which is why it works. If you cannot hear a passage in your head, you do not yet know it — and finding that out is useful.
Work on one small place with the volume at its lowest. On a digital instrument you can turn down rather than turn off. Very quiet playing is also technically demanding in a good way: it requires control of the arm rather than force.
Being a good neighbor, practically
Tell them before they have to tell you. A short, friendly note or conversation — I am learning the piano, I practice around seven in the evening for half an hour, please tell me if it is a problem — changes how the sound is heard. Noise from a stranger is an intrusion; noise from a person you have met is a neighbor practicing.
Keep it to the same predictable window. Predictable sound is far easier to live with than sound that appears at random.
Do not repeat the same two bars forty times at full volume. This is the one that genuinely wears on people, and it is exactly what good practice requires. Do the repetition quietly or on headphones, and save the playing-through for the times you want to hear the room.
Put the instrument against an internal wall, not a shared one, if you have the choice — and not directly against the wall itself.
What not to bother with
Egg cartons, foam tiles and blankets on the wall are the classic first purchase and they do very little for what you are trying to solve. That material changes how a room sounds inside itself; it does not stop sound leaving. Real soundproofing means mass and separation, which a renter cannot install. Spend the money on a rug, a mat under the instrument, and headphones.
The thing worth holding onto
An adult who practices for twenty quiet minutes a day, on headphones, with a rug under the stand, will be playing real music within a year. An adult who waits until they live somewhere with thick walls will not, because that day arrives much later than they think and the habit never got built.
Play quietly and play anyway.
And if you cannot hear yourself properly
Practicing on headphones makes one thing harder: judging your own balance and sound in a real room. That is exactly the kind of thing a second pair of ears can settle.
Record two minutes with your phone — speakers on, quietly, or with the phone picking up the room — and send it. The written feedback is free, and it will tell you what your hands are doing, which headphones cannot.