It depends on various factors such as the distance between your neighbor's piano and your conversation, the level of insulation in the walls, the volume of both the piano and your conversation, and the acoustics of the building.
Generally speaking, pianos are capable of producing relatively loud sounds, especially when played vigorously. If your neighbor's piano is nearby and the walls between your units are not well-insulated, there is a higher likelihood that some sound may transfer through the walls and be audible to you.
Conversational sounds, on the other hand, tend to have a lower volume compared to musical instruments like pianos. If you are having a normal conversation at a reasonable volume, it is less likely that the sound will travel through the walls with the same intensity as the piano. However, if there are thin walls or poor insulation, some sound may still be transmitted.
It's important to note that sound transmission can be unpredictable, and the acoustic properties of buildings can vary. Factors such as the construction materials, thickness of walls, and presence of soundproofing measures can all affect the extent of sound transfer between different spaces.
To minimize sound transmission, you can consider using additional soundproofing measures like sealing gaps around windows and doors, adding acoustic panels or insulation to the walls, or using background noise or white noise machines to mask the sound.
If you are concerned about the sound levels between your neighbor's piano and your conversations, it might be worth discussing the issue with them to find a mutually acceptable solution.