Sound and Musical Instruments

Musical Instruments (String Instruments)Laws of Strings

Musical Instruments a device created or adapted for the

purpose of making musical sounds

String Instruments A musical instrument that produces

sound by means of vibrating strings. Also called chordophones.

Lutes – strings are supported by a neck

guitar

violin

Harps – strings contained in a frame

Zithers – strings mounted on a body

Sound Waves Created by a vibrating object. Vibrating object = source of

disturbance that moves through the medium.

Examples of medium: vocal chords, vibrating guitar strings

the particles of the medium through which the sound moves is vibrating in a back and forth motion at a given frequency

Frequency the number of waves that

pass a fixed point in unit time. “how often” the air particles

vibrate. Measured as the number of

complete back-and-forth of a particle of the medium per unit of time.

Factors that determine frequency (plain steel string)

tensionlengthmass per unit length of the string

Formula:

Frequency and length of string

Longer string = lower frequency Frequency is inversely proportional to

the length of the string Change in length of string = different

frequency Shorter strings = higher frequency =

higher pitch

Frequency and thickness of string

Diameter = thickness Thick strings vibrate slower Slower vibrations = lower

frequencies

Frequency and tension

Tension – how tightly the string is stretched

Tighter string = higher tension = higher frequency

Loosening string = lower tension = lower frequency

Quiz. True or False.

The relationship between tension and frequency is determined by how fast the wave moves on the string.

Thin strings vibrate faster and have higher frequencies than thick ones.

Higher frequency = higher pitch Loosening the string gives it a higher

frequency while tightening the string gives it lower frequency.