Voice overview - chapter 15, 16, 17

 * anatomy - see pictures on pg 337

   * very complicated system
     * vocal chords (or folds) 
        * 100,200,300 Hz normal speech (man,woman,child)
        * muscles change tension to affect pitch
     * three main parts of vocal tract : 
        * pharynx
        * mouth
        * nose
     * resonances of vocal tract give 
       "formants" : peaks in vowel spectra; see pg 346

   * simple models
     * 17cm pipe with one end closed, one open
       * 500Hz, 1500Hz, 2500Hz resonances (typical /e/ vowel)
     * two tubes of varying diameter can model of vowels

   * speech recognition by computer
     * sound spectrograms : see pg 168

   * singing
     * different registers (head, chest) caused by
       * air pressure muscles (diaphram and chest) and
       * adjustments to layrnx (around vocal chords)
       * passive vs active, like clarinet reed vs trumpet lips
       * stress vs strain on vocal ligaments; see pg 386
     * trained vocalists can do cool funky stuff 
       with extra formants