CSAD 320 Acoustics of Vowels

for quiz 8

formants and perturbations

each formant (F1, F2, F3) is associated with perturbations in the oral and pharyngeal cavity (i.e., constrictions)

vowel

acts as the nucleus of a syllable; contains a glottal (voiced) sound source; contains resonant frequencies in a relatively unconstricted vocal tract (as compared to consonants)

constriction for vowels

small constrictions in the vocal tract do occur, as movement of one or more articulators causes shape changes or different configurations in the vocal tract; the changes cause perturbation

perturbation

an irregularity of frequency or amplitude

resonant cavities

each cavity (pharynx, oral, and nasal) acts as its own resonant cavity, allowing us to have the wide varieties of air flows, sources, and filters (in acoustic terms) that produce speech

pharynx

broken into three cavities - nasopharynx, oropharynx, and laryngopharynx

nasopharynx

behind the nose, above the velum

oropharynx

below the velum, above the hyoid bone

laryngopharynx

below the hyoid bone, above the base of the cricoid cartilage

filtering

constrictions in the vocal tract that change the sound source; for vowels, filtering of resonant frequencies results in formants; relatively unrestricted except for slight perturbations

perturbations for vowels

lip rounding and lowering the mandible (lower jaw)

larger volumes

amplify lower frequencies; also true for longer tubes, because longer wavelengths fit better in a larger/longer volumes (low frequencies have longer wavelengths)

smaller volumes

amplify higher frequencies; also true for shorter tubes

what pharyngeal cavity volume relates to

F1

what oral cavity length relates to

F2

what lip rounding relates to

lowers all formants, but especially F3

increased pharyngeal volume

lowers F1

decreased pharyngeal volume

causes higher F1

pharyngeal volume size

relates to tongue height; lower tongue/mandible = a more retracted tongue base → decreases overall pharyngeal volume; elevated tongue/mandible = less retracted tongue base → allows for more room in pharynx

increased oral cavity length

lower F2

decreased oral cavity length

causes higher F2

tongue advancement/retraction

plays a role in F2; posterior tongue advancement → shorter oral cavity → higher F2; posterior tongue retraction → longer oral cavity → lower F2

absolute values of F1, F2, and F3

do not exist, as formant frequency depends upon vocal tract length and resonating cavity size

rules of F3

most effected by increased lip rounding (though all formants decrease with increased rounding); more important for high vowels; rounding lengthens the vocal tract, and F3 is only affected by lip rounding

vocal tract articulatory posture

tongue height (oral cavity): can be high (closed), mid, or low (open) = F1; tongue advancement: can be front or back = F2; lip rounding = F3

tense vowels

produced with greater muscle contraction; produced at the extremes of articulatory posture, with the tongue higher in the oral cavity

acoustic result of tense-lax dimension

duration; tense vowels are longer, while lax vowels are shorter

duration

an important dimension of vowels, but NOT the only distinguishing feature for pairs

short vowels

generally do not appear in open syllables (those ending in a vowel)

closed syllables

those ending in a consonant; may contain either long or short vowels

diphthongs

two vowels within the same syllabic nuclei, with a smooth glide from one vowel to the next

onglide

articulatory starting point of the diphthong

offglide

articulatory ending point of the diphthong

diphthong characteristics

each one has characteristics of F1→F2 formant pattern; the actual value of formant frequencies varies across speakers, but two factors are stable: rate of change of vowel and relationship between vowel formants