THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

18.9 Strings 525Figure 18.14. Mechanism for shortening strings in the harp for transposing tones.even further so that the string is a whole tone higher, as shown in panel C. Eachpedal operates on strings with notes having the same letter notation, i.e., the Cpedal controls all the C strings; the D pedal all the D strings, and so on. The harpis generally tuned in the key of C flat. The pillar of the harp serves to bear thestresses produced by the stretched strings and to serve as a housing for the rodsconnected to the pedals and for the transposing mechanism of Figure 18.14. Theoverall height of the standard harp is approximately 173 cm. The harp is playedeither by plucking the strings with the fingers or by sliding the fingers over thestrings in a manner referred to as a glissando. There are 44 strings, usually madeof gut (some bass strings may be constructed of silk overlaid with metal wire forgreater density); portable models have as few as 30 strings.Figure 18.15 shows views of a ukulele, guitar, mandolin, and banjo. The ukuleleis a small version of the guitar. The former consists of four strings, tuned to D 4 ,F 4 ,A 4 , and B 4 , stretched between a combined bridge and tailpiece attached to thetop flat surface of the body and the end of a fretted fingerboard. The body itselfconsists of two flat surfaces fastened together by a contoured panel at their outsideedges. The bottom of the body is mechanically attached to the top by a post, andthe cavity of the body, coupled to the external atmosphere, acts as a resonator.The body of the ukulele may be made of wood or steel or plastic. The 61-cm longinstrument is played by strumming the strings with the fingers, and the resonantfrequency of each string is varied by the fingers pressing against the frets that arespaced so the sounds produced by stopping a string on any two adjacent frets are