Evoked Potential

Acoustic Phonetics

Vowels

Reading Spectrograms: Words 1

Consonants

Reading Spectrograms: Words 2

  • Lips, teeth, tongue, vocal chords, larynx and pharynx are key manipulators
  • The epiglottis covers the airway so food doesn't get into your lungs
  • The vocal tract: the vocal chords through the mouth and tongue influences the different sounds that you can make
    • air is forced from your lungs through the vocal chords
  • vowel sounds have unique signatures in that they have a different formant structure
  • formant - each of several prominent bands of frequency that determine the phonetic quality of a vowel
    • ​there is a lot of speech perception related to formants
    • formants are where the frequencies are enhanced
  • ​plosive - there is closure and then a build up and release
  • frcatives - air is constantly passing through, create friction
  • affricate - combination sound, e.g. d going into s is the "ja" sound
  • the different tongue positions give rise to a different spectra of formant
  • patterns are the same but vary from individual to individual
  • the vocal tract changes shape by changing the shape of the tonge
  • vowel sounds are smooth
    • tongue height, high, medium, low tongue position, front, mid back, lip rounding close, open
  • consonant sounds have to make a constriction in your vocal tract which will allow you to stop your air flow for a brief period creating turbulence with that process
  • consonants can be distinguished in terms of 
    • voicing - whether or not vocal folds are vibrating in the larynx
    • place - site of constriction or closure in the vocal tract
      • bilatial, alveolar, dental, palatal
    • manner - type of constriction (plosive, fricative, affricate, nasal approximates)
      • plosive, fricative, affricate, continuants (narrower of that as a vowel but not as much as a consonaant)
  • the vocal tract changes as a function
  • speech pattern consists of various complex processes, vowel sounds, consonant sounds
  • the difference between male and female vocal chords is between 100Hz, have a different fundamental frequency, vocal fold stays the same but the shape changes it
  • phonemes - english contains about 40 phonemes
  • spectrogram - representation of the frequency and intensity of the speech signal over time
  • harmonic and a formant - harmonics are related to fundamental frequency of vocal chord vibration
    • you have a fundamental and then next harmonic
    • formant is representative of where in the vocal tract the sound is resonated, not the fundamental frequency
    • some of the darker areas of the spectrograms are the formants
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