CSD 2464 Lecture 1: CSD 2464 Chapter 6

5 Pages

Communication Sciences And Disorders
Course Code
CSD 2464
Jennifer Dalton

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CSD 2464 Chapter 6 Consonant Types • Sonorants (nasals, liquids, glides) are similar to vowels: o Free airflow, articulation shapes vocal tract cavities o Are characterized by formant frequencies o Have a periodic laryngeal source (are voiced) • Obstruents (stops, fricatives, affricates) o Blocked/restricted airflow o Aperiodic sound source in upper vocal tract o May be voiced or voiceless o Obstruents in clinical populations ▪ Hyponasality or hypernasality may result from problems with velopharyngeal control • Cleft palate • Motor speech disorders ▪ Poor control of VP may impair production of oral obstruents that require buildup of intraoral air pressure ▪ Problems of interarticulator timing in motor speech disorders may affect VOT and stop voicing constrasts Sound Sources in Consonants • Voiced consonants: periodic laryngeal source • Voiceless consonants o Supraglottal noise sources o Aperiodic laryngeal source noise, aspiration • Obstruents: supraglottal noise sources o Stop bursts- release built-up pressure, transient noise o Friction- air forced through narrow channel becomes turbulent, sustained noises o Voiced obstruents combine periodic and aperiodic noises Resonant Consonants Production of Approximates • Approximates o Liquids (l, r) ▪ Tongue tip is raised toward alveolar ridge (superior longitudinal muscle) • /l/ o Tongue tip contact with alveolar ridge o Slides tongue down: lateral emission of air • /r/ o No tongue tip contact with alveolar ridge o Retroflexed (tongue tip bent up) o Lip rounding o Glides (w, j) ▪ /j/ • production is similar to /i/ o High front tongue position o Genioglossus is active • Formant values similar to /i/ o Low F1, high F2 • Formant transitions vary ▪ /w/ • Production is similar to /u/ o High back tongue position, rounded lips o Styloglossus, orbicular oris are active • Formant values similar to /u/ o Low F1 and F2 • Have limited constrictions that alter resonant frequencies • Formant transitions typically faster for vowels • Classification as consonants based on syllable position o Consonants occur on periphery o Vowels are nuclei Oral Speech Sounds and the Velum • Most speech sounds are oral o Soft palate elevated against posterior pharyngeal wall o Velopharyngeal port is closed o Levator palatini muscle is active o Degree of VP port closure varies ▪ Tighter for oral obstruents ▪ Moderate for high vowels ▪ Looser for vowels • Nasals require open VP port • In nasal stops, oral cavity is blocked at same places of articulation as for stops o Acoustics of nasal stops: ▪ Opening of VP port creates large resonant cavity which results in low frequency nasal resonants ▪ Amplitude is low Production of Fricatives • Aperiodic sound source in upper vocal tract o Airflow forced through constriction creates turbulence • Can be formed at many places in vocal tract o Labiodental [f v] ▪ Lower lip approximates upper incisors ▪ Orbicular oris inferior is active o Linguadental [Ө ð] ▪ Tongue tip approximates upper incisors ▪ Superior longitudinal muscle is active o Alveolar [s z] ▪ Tongue forms constriction at alveolar ridge ▪ Air flows through midline groove of tongue against teeth ▪ Short anterior cavity emphasizes high frequencies ▪ /s/ source and filter • Noise source at alveolar ridge; small anterior cavity • Quarter-wave resonantor between alveolar ridge and lips • High frequencies emphasized for alveolar fricatives • Lower frequencies emphasized for alveopalatal fricatives o Postalveolar [∫ ʒ] ▪ Tongue forms groove in alveopalatal region ▪ Lips are often rounded ▪ Longer anterior cavity emphasizes lower frequencies o Glottal [h]
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