Notes

Outline

Beethoven (1770-1827) String Quartet in F major Op. 18, No. 1

Five Components  of Instruments 1. Energy source 2. Energy connector from     the source to the     instrument itself

Components of Instruments 3. Primary oscillator 4. Resonant oscillator 5. Sound emitter

1. Energy Source Muscle Power Arm Motion Finger Motion Lung Motion Foot Motion Electrical Power

How much Energy? Typical Instrument = 50W ~ 1% is converted to sound Total Orchestra ~ 60W For 90 dB = 10-3 W/m2 at an ear of 1 cm2 P=10-7 W!!

2. Energy Connector Transmits from Source to the instrument itself Examples: Violin family Piano Wind Instruments Organ

3. Primary Oscillator The part of the instrument that vibrates and is directly responsible for the sound. Examples: Strings, reeds, lips, surfaces, air.

4. Resonant Oscillator Amplifies certain frequencies to produce a harmonic series. Examples: Violin family Piano Winds Drums

5. Sound Emitter Gets the sound out.  Usually via a hole or opening Examples: Violin family Piano Winds Drums

String Instruments 1. Energy Source Arm motion for bowing Finger motion for plucking (violin or guitar) or moving keys (piano)

String Instruments 2. Energy Connector Bows Hammers Picks or Quills Fingers

String Instruments 3. Primary Oscillator Strings

String Instruments String Variables related to frequency Length Tension Density

String Instruments Frequency Variation Many Strings of Different Length, Tension, Density Change Effective Length of String

String Instruments Activation Location Changes timbre by reducing some harmonics No nodes at activation points

String Instruments

String Instruments

String Instruments

String Instruments 4. Resonant Oscillator Wooden Box or Sheet of Irregular Shape Example: Violin (MI CD)

String Instruments 5. Sound Emitter Opening in the Body of the Instrument Examples: Violin and Guitar, etc.

Wind Instruments Energy Connector Air From Player’s Lungs or From a Compressor

Wind Instruments Primary Oscillator Reed(s) Player’s Lips Air Near Opening Into Which Player Blows

Wind Instruments Resonant Oscillator Air Column Within the Tube that Constitutes the Body of the Instrument

Wind Instruments Frequency Variation Tubes of Different Length Interlocking Pipes System of Valves Series of Holes

Wind Instruments Sound Emitter Hole in the Opposite End

Percussion Instruments Energy Connector Sticks Mallets Hands Fingers

Percussion Instruments Primary Oscillator Two-Dimensional Surface Three-Dimensional Surface

Percussion Instruments Resonant Oscillator Wide Variation - Depends on the Specific Instrument