The violin moves from note to note with the the direct stopping of the strings by the fleshy part of the fingertips. This method of stopping produces a tone quality which is slightly dampened, yet "assertive and flexible." (Backus 1977) For instance, rapidly moving the fingertip in a rocking motion will add vibrato to the tone. The movement of the stops on the string effectively changes string length and therefore frequency of vibration by just a few hertz. All periodic waves will be a derivative of the new string length and since the difference in frequency is just a few hertz, the note does not change.
The oboe is tuned by adjusting the length of the air column. This adjustment is made by moving the reed in or out of the body. The reed is pulled out if the instrument is sharp and pushed in if flat. The most important factors in playing the oboe is the making of the reed and the control exercised by the mouth. Both can significantly affect pitch.
To play individual notes, a combination of keys is pressed.. These keys cause holes to be either opened or closed on the body of the oboe. This adjustment effectively changes the volume of the air column and the frequencies which will stand within the instrument. (see figures 7& 8)
A timpani is tuned by adjusting the membrane tension of the drum head. This tension is adjusted in some drums by turning several hand screws, which act on the ring securing the membrane, and are fixed to the shell. In other drums, the tension can also be modified by a pedal or hand mechanism which rapidly modifies the tension through rods connecting to the ring. The tone varies according to the texture of the head of the stick which strikes the head and the area of the membrane struck.
The timpani is usually not tuned from note to note to create the individual notes in a melody, but instead tuned from song to song. Multiple timpani are usually used in a musical piece, rather than tuning mid-passage. Each drum is tuned to a different pitch. A typical composition will employ two or three timpani and sometimes more.