–Speech is results from a combination of sound source(s) and the filtering provided by the vocal tract.
Sound sources for consonants
–Periodic vibration: voice
–Aperiodic vibration
•Turbulent: sustained noise
•Transient: single vibration (gunshot)
Descriptive Phonetics
–Manner of Articulation: how the consonant is produced
–Place of Articulation: where the consonant is produced
–Voicing: are the vocal folds vibrating
•Each descriptive phonetic phonemic feature has an acoustic realization
Stop (plosives):
–Descriptive: sound produced with a complete blockage (both oral and nasal cavities) of the vocal tract during which time no air flows and pressure increases. An explosion occurs at the release.
–Acoustic: period of silence (complete blockage of vocal tract) followed by a burst of energy (release of air pressure). Burst is a transient vibration.
Fricative:
–Descriptive: sound produced with a partial oral cavity blockage (nasal cavity blocked). Air pushed through the blockage becomes turbulent
–Acoustic: sound produced with a period of sustained noise
Affricate:
–Descriptive: combination of a stop (complete blockage of both oral and nasal cavities) released to a fricative (partial blockage)
–Acoustic: period of silence followed by a burst of energy followed by sustained noise
Approximant:
–Descriptive: sound produced with the least constricted vocal tract of all the consonants
–Acoustic: formants like vowels. Multiple formants, although usually weaker than the surrounding vowels
Nasal:
–Descriptive: sound produced with an oral cavity blockage but with the nasal cavity coupled to the vocal tract resulting in nasal resonance.
–Acoustic: formants like vowels. Low formant reflecting nasal resonance. Higher formants usually weak or absent
Acoustic Characteristics of Place of Articulation
Varies depending on the manner of articulation
Stop consonants:
–transition (movement-change in frequency over time) of the second and third formants
Fricatives:
–frequency location and strength of the noise energy
Approximants:
–onset (beginning) frequency of the second and third formants
Nasals:
similar to the stop consonants
Acoustic Characteristics of Voicing
Voicing varies depending on the manner of articulation and position in word (initial/final)
Stop consonants
•Initial (prevocalic) position: Voice Onset Time (VOT): time between the release of the stop and the onset of voicing for the following vowel