PH 105 Dr. Cecilia Vogel Lecture 15

OUTLINE  string vibrations  plucking vs bowing  envelope  tunings  specific instruments

Review Strings  Normal modes of vibration of string  are  demo  Fundamental mode  _______________ fits length of string   pitch, based on

Pitch of String  to change the pitch, can change     calculate v  why isn’t it 

String Harmonics  The n th mode is  its frequency is  its wavelength is  There are  length of string =  1 st harmonic is  2 nd harmonic is 

Plucked Modes  Normally, the motion is  but a  A string plucked at center  has shape of a  which  A string plucked  will not have  Recall: harmonics lend

Plucked String  The triangle wave in plucked string  

Bowing  Bow also pulls string to a point  but bow  until the wave  then the string  before being pulled again.  Occurs  Note:  If you bow too gently,   If you bow too hard, 

Bowed Modes  The wave in a bowed string is  more like a  which has  The harmonic content,   of a bowed instrument is very different from

Envelope of Plucked String  The envelope of a plucked string  has a rapid ____  and a long ______  no sustain/release  the harmonic content of the decay becomes _____with time.

Envelope of bowed String  The envelope of a bowed note  has a less rapid _____  and a quick _____.  Sustain lasts as long as bowing continues  sustain has fairly constant ______  the release is similar to decay of plucked string.

Violin Strings  G 3, D 4, A 4, E 5  each tuned a  Recall a fifth is a ratio of  an interval of

Violin Demo  G 3, D 4, A 4, E 5  Can you play G 4 on D-string?  by making the string  play harmonics?  Demonstrate open notes (  ), fingering (__), tuning (__), interval, pizzicato vs bowing, play something

Guitar Strings  E 2, A 2, D 3, G 3, B 3, E 4  (12 string has 6 pairs, same note or octave)  each tuned a  except E:B, which is a  fourth is about :  major third is about:

Guitar Strings  E 2, A 2, D 3, G 3, B 3, E 4  Can you play F 2 on E-string?  _______ higher  making the string ______ by factor of ______  Frets placed about 1/18 distance from the previous fret (or nut) to bridge  fig  18:17 =  1/ more accurate than 1/18

Announce:  Exam Friday  Chapters  lectures:  homework  Provided 

Summary  Normal modes of string  harmonics  Non-normal modes  fundamental + specific overtones  bowed vs plucked  Dependence of pitch on  density, tension, length  Intervals  Envelope  bowed vs plucked