The tuning is the appropriate maintenance of the piano and it is recommended to be executed twice a year, even if the piano in no longer in use. The piano is a delicate musical instrument whose strings are under immense pressures – they exceed a total of 30 tonnes (!) – in order to produce the desired frequencies.
Over time they loosen and the tone of the piano is altered. This happens even if no one uses the piano. Regular tuning keeps the instrument to the correct tone and protects the piano from other problems that may occur.
The tone of the piano, which certainly concerns all other instruments too, is set at 440Hz. This refers to the frequency of its 49th note (A). Over the years the tone went through various stages and there was a time when each country had its own pitch of musical tone, something which made the life of artists difficult. Finally, the adoption of A49 to 440Hz as an international pitch was achieved at an international conference held in London in May of 1939 and has since been recognized as the standard international pitch.