2,3 Therefore, the source of all of the sound from a piano is still considered to be the string. These anomalous components in the sound from a piano, commonly referred to as phantom partials, were first reported in 1944, 1 and work over the following 70 years resulted in the conclusion that they originate in the stretching of the string as it vibrates. The sound originating in the wood occurs at frequencies that are sums and differences of the frequencies found in the vibrations of the string, but they are created in the wood not the string. That is, the wood can be a source of sound as well as the string, and it is not always simply a filter. Experiments have shown that the wooden parts of the piano can produce sounds that are not created in the string. The work reported in this presentations shows that this idea of how the piano works is flawed. The wood can change the balance of the sound created by the string, but it cannot add new sounds. The vibrations from the string are said to be filtered through the bridge and soundboard because these wooden components do not transmit every pitch equally efficiently. This type of arrangement, where there is a source of the sound (the strings) and a mechanism to transmit the sound to the air (the wooden parts of a piano) is often referred to as a source-filter system. The final sound depends both on the relative power in each of the harmonics in the string, as well as how efficiently these sounds are transferred to the air. The string vibrations produce many different musical pitches simultaneously, most of which are harmonics of the note being played.

The unique sound of the piano, or any stringed musical instrument, begins with the vibrating string. Presented Thursday morning, November 8, 2018, 8:55-9:10 AM, Crystal Ballroom (FE) Popular version of paper 4aMU1, “Are phantom partials produced in piano strings?” Thomas Moore – Neldner – Rokni – of Physics

Piano strings theory