Musical Acoustics Demonstrations

Pitch of Harmonic Sequences, with Missing Fundamental

Background

When the spectral recipe, or amounts of different frequencies in a sound, is changed, there might be changes in either pitch or tone color (timbre), or both.  Which of these changes as a result of taking away various harmonics? 

Instructions

The first two tones you will hear are pure tones at 250 Hz and 500 Hz, which also will be the first two harmonics of the sounds that come later.You should try to sing these and match the pitch with your voice.   These two tones are an octave apart, and you can hear the pitch go up.  The next. 5 tone pairs consist of the 250 Hz pure tone followed by a complex tone with harmonics of 250 Hz,  up to harmonic number 6.  But, some harmonics are removed each time.  The harmonics present in these five tones are:
(1,2,3,4,5,6),   (2,3,4,5,6),   (3,4,5,6),   (4,5,6),    and,  (2,4,6). 
In which examples do you hear the pitch go up an octave?
Does the pitch go up an octave if the fundamental frequency (first harmonic) is removed?
Does the tone color change?

  • Play the sound file
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    Csound files

  • harmonic.orc
  • harmonic.sco
  • harmonic.csd
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