Even if the walls are properly designed for low noise transmission, flanking noise through wall and ceiling penetrations and joints, or the ventilation system, can be a big pathway for noise transmission.
Sometimes tenant improvements requires re-designing the space dividing walls. We have consulted a veterinary clinic for reconstructing walls to contain the sound of barking dogs (~95dB) on the other side of a wall from a very quiet financial advisor building (~35dB). Another challenge was a high-energy dance fitness class that shared a wall with a set of quiet professional offices.