In the Pedal Steel Guitar, one can easily produce the same-pitched note at three different locations, by selecting to change the string thickness or the string tension, or the length of the string. The result will always have the same "pitch", but the diffeernce in timbre is noticeable; and even forms the basis for producing some highly-esteemed licks. In every case, the 3 physical parameters of any such selection can be used to predict from First Principles, the resulting Pitch of the plucked note. Can physics likewise be used to predict "timbre"? Can First Principles be used to define a framework for the =measurement= of timbre?