How does a String Make a Sound?
• When a string is made to vibrate by rubbing or plucking, it communicates a frequency to the surrounding air. When these vibrations reach the tympanum (eardrum), they are perceived as sound. Without a medium (air or water), sound cannot be propagated.
• Rubber Band Shoe Box Demonstration
What is Resonance
• When one object vibrating at the same natural frequency of a second object forces that second object into vibrational motion.
• The word resonance comes from Latin and means to "resound" - to sound out together with a loud sound.
• Resonance only occurs when the first object is vibrating at the natural frequency of the second object.
• Tuning Fork Demo
The Overtone Series
Fundamental Tone
First Harmonic- One Octave
Second Harmonic-One Octave + A Fifth
Third Harmonic-Two Octaves
Fourth Harmonic-Two Octaves + A Third
Fifth Harmonic- Two Octaves + Fifth
Sixth Harmonic – Two Octaves + Minor7th
Seventh Harmonic-Three Octaves
If the finger is placed at a whole fraction of the length of the string, the vibration produces a note in harmony with the fundamental note. This principle was discovered by Pythagoras already two thousand years ago.
Sympathetic Vibrations • Pythagoras discovered that if one string vibrates with twice the
frequency of an identical string, we hear the higher frequency as one octave higher in pitch than the lower frequency
• The vibrating systems on most musical instruments are made up of two or more vibrating systems working together to produce sounds loud enough to be heard by the human ear.
• Examples of instruments with two or more vibrating systems include the membranes of leather stretched across the tensioning loop of a drumhead, the strings and the sounding board of a piano.
• Other examples are the strings and the body of a guitar or violin, or the reed and air column of the air column of the clarinet.
• Demo On Piano