Читать книгу Blues Guitar For Dummies - Jon Chappell - Страница 25

A guitar is a string instrument, related to the violin and cello in that it generates tones by means of a vibrating string. You set the string in motion by striking or plucking it, which causes it to vibrate, which produces a musical pitch. For the sound to be heard by human ears, the vibrating string must be amplified in some way. In acoustic instruments, the body acts as the sound chamber, or acoustic amplifier. In electric instruments, the body contributes no amplification to the sound at all. Instead, the amplification is produced by the amplifier, which attaches to the guitar by a removable cable.

Some factors influence the string’s pitch:

 Fretting: You can also change the pitch by shortening the string or, more practically, shortening its effective vibrating length. That’s what you do when you fret (press a string to the fretboard at a certain location on the neck). You’re playing shorter versions of the same string. Fretting allows you to play any pitch — flat, sharp, or natural — in the guitar’s entire range. Check out Chapter 4 for more information about fretting.

 Mass: A string’s mass, or thickness, influences its pitch. The thicker the string, the lower the pitch. That’s why the low-pitched strings are thicker than the high-pitched ones.

 Tension: You can change a string’s pitch by varying the tension of the string. Higher tension produces higher pitched notes. On a guitar, you tighten and loosen a string with the tuning key — a geared mechanism located on the headstock. Turning the tuning key is also how you tune the guitar, which is covered in Chapter 3.