Strings (tennis)
In tennis, the strings are the part of a tennis racquet which make contact with the ball. The strings form a woven network inside the head (or "hoop") of the racquet. Strings have been made with a variety of materials and possess varying properties that have been measured, such as dynamic stiffness, tension retention, thickness (gauge), string texture (shape of the string), and rebound efficiency.
Sympathetic string
The guitar is normally unable to produce effective sympathetic string resonance for tones other than E (resonance from the 6th and 5th strings, tuned to E and A, respectively), B (from the 6th string), D (from the 4th string), and A (from the 5th and 4th strings). (The treble strings are negligible in practice, as they are almost constantly being fingered.) However, the ten-string guitar invented in 1963 by Narciso Yepes, adds four strings tuned to C, A, G, F, which resolves the imbalance of resonance on the guitar. By adding the abovementioned resonances and, of course, their fifths (the fifth being a strong resonant frequency)—that is to say, G, F, D, C—the guitar's strings now resonate more equally with all 12 notes of the chromatic scale, bringing the guitar's sound closer to the consistency and sustainability of the harpsichord and piano.