Pregunta: 1. A pure tone is a sound produced byA. A sinusoidal sound wave of one frequencyB. The sum of sine waves of various frequenciesC. A square sound wave D. A single note on a musical instrument 2. A guitar string vibrates noticeably when waves traveling up and down the stringA. add

1. A pure tone is a sound produced by

A. A sinusoidal sound wave of one frequency

B. The sum of sine waves of various frequencies

C. A square sound wave

D. A single note on a musical instrument

2. A guitar string vibrates noticeably when waves traveling up and down the string

A. add up

B. produce vibration in the string

C. produce vibration under resonance condition

3. Resonance in a guitar string occurs when waves going in the same direction are in

A. big

B. in phase

C. out of phase

4. If “L” is the length of the string and “λ” is the length of the waves going up and down the string, there is vibration at resonance when

A. Ne*(λ/2) = L

(Ne are integers, Nimp are odd numbers.)

The vibration frequencies of the string at resonance are the fundamental f0 and the harmonics fn. The fundamental is the easiest to trigger and is known as the natural frequency of vibration of the string. The f0 = (T/μ)1/2/2L and the others are the harmonics:

A. Ne* f0 (Ne > 2)

B. an infinite continuity of other

C. relatively few more

D. Nimp* f0 (Nimp > 3)

Generally, playing the string causes mainly the fundamental vibration, but also a bit of various others (among the harmonics). Now the transfer of energy from the vibrating string to the air (to produce sound waves) is best accomplished if the air is in a situation (partially trapped) such that it can also vibrate in resonance in one or more of the same frequencies at which the string vibrates. This is accomplished, at different levels of power transmission for different string frequencies, in the guitar's soundboard. Thus, the frequencies with which the string vibrates (fundamental and some harmonics) begin to make the air in the soundboard vibrate more easily, although at different degrees of intensity. Finally, the vibrating air in the guitar body, together with the vibrating string, generates the sound waves in the free air that reach our ears so that we hear the complex and particular sound of playing a string on the guitar. Therefore, the sound a note of the string played on the guitar is

A. a sinusoidal sound wave of one frequency

B. the sum of sine waves of various frequencies

C. the sum of sine waves of various fundamental frequencies

D. the sum of sine eaves of various frequencies (fundamental and harmonics)

in amount(s) that depend on how the string was plucked and how there was resonance in the box.