Different types of piano maintenance
"Tuning" the piano refers to adjusting the tension of the strings to achieve the desired pitch for each note.
"Voicing" is the process of altering the tone to be brighter, duller, clearer, fuller.
"Regulating" is the adjustment of the mechanism to improve evenness of touch, response and dynamic range.
"Address friction" reducing unwanted friction within the action and equalising wanted friction between keys.
"Repair" involves replacing or fixing worn or broken parts.
Ornaments on the piano and other causes of strange noises
One of the biggest causes of strange noises from pianos is the sympathetic vibration of objects which are placed on top of the piano such as ornaments, trophies, pictures, metronomes. While it is acceptable to place light objects on your piano, a thick cloth placed on the piano first will prevent vibration and also protect the finish from scratches. Other objects in the room can also vibrate in sympathy with the piano - light fittings, windows, music stands, drums, pictures to name but a few. If the noise stops when a particular object is moved or touched, that is the source of the sound.
Piano parts themselves can also make unwanted noises. Hinges, loose panels, missing felts, pedals, soundboard faults, debris on the keybed and soundboard, and objects leaning against the back of an upright piano are all common causes of unwanted noises.