“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Vowels and Diphthongs –Vowels are formed when sound produced at the glottal source is selectively filtered and resonated in the vocal tract –English has 15 vowels and 4 diphthongs which are commonly encountered –Movements of tongue and lips is correlated; as tongue moves toward front of mouth, lips are spread (examples: eat, it, at) –As tongue moves back, lips are rounded (examples: caught, boat, boot)

“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Vowels and Diphthongs –Most crucial variable in vowel production is the point at which the tongue creates the greatest degree of constriction in the vocal tract –Typically this is the highest point in the tongue’s profile –Vowels may also be differentiated by degree of tension in tongue and jaw during production –Tense = tongue spread, Lax = narrower –Examples of tense-lax pairs: eat/it, ate/et (as in etcetera) –Some words contain both members of a tense-lax pair (spoon pronounced spoon or spoo-on)

“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Vowels and Diphthongs –Formant frequencies of vowels determined by length of vocal tract –But relative shape of tract (and overall acoustic pattern) will be similar for all speakers –Men, women, and kids will all have tongue in high back position for “boot” and high front for “beet” –Listeners have a “normalization process” after hearing the first few syllables of an utterance, such that exact formant frequencies are generally unimportant to comprehension –Analogy: handwriting analysis

“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Vowels and Diphthongs –Lieberman (1973) suggests that listeners use vowels in eat, ought, and boot to “calibrate” speakers –Studdert-Kennedy (1975) argues that vowels are only normalized in a consonant context –Normalization in HI not yet studied –In running speech, vowels are coarticulated and not necessarily produced same way each time –However, speakers have an “ideal” vowel target in mind

“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Vowels and Diphthongs –Ling says that HI kids must establish their own ideal vowel targets through sustained production –Without ideal targets, HI kids may neutralize all vowels, thereby reducing intelligibility Diphthongs = when two vowels are produced as a glide –Examples: pie, cow, toy, play, here –Dialectical differences largely due to vowels and diphthongs –Is “can” one syllable or two?

“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Articulatory Targets and Formant Values –Use Table 13.A as a guide –Teacher should follow 4 steps –1. Ensure that child’s tongue rests on or near the lower front teeth for all vowels except those associated with r, and that the velum is raised during production of all vowels (no nasal resonance) –2. Know own articulatory patterns thoroughly –3. Develops subskills as described –4. Discourage exaggeration (teeth no more than 1 cm apart when jaw is open)

“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Subskills and Teaching Strategies –All vowels require: 1. Differential shaping of the vocal tract to produce the required formant structures 2. Ability to maintain each target vocal tract configuration for at least three seconds 3. Rapid repetition of each vowel target 4. Rapid alternation of the articulators so they can assume their target positions for each vowel easily from their previous position 5. Independent control of the larynx (sound source) and the articulators (sound filter)

“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Subskills and Teaching Strategies –“The extent to which vowel differentiation occurs spontaneously usually depends on the amount of residual hearing that is present and the extent to which it is used. The wider the frequency range of the child’s hearing, the greater the variety of vowels he will be likely to produce if appropriate hearing aids and extensive exposure to speech have been provided. The child’s orosensory-motor differentiation of spontaneously produced vowel patterns will also depend on the effectiveness of the reinforcement that has been supplied.” p.230

“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Teaching Strategies Related to Vocal Production –Must be determined for each child according to extent of and use of residual hearing –All other variables (age, previous experience) are of secondary importance –Kids with hearing up to 3,000 Hz may be expected to imitate and identify all vowels through use of audition –Only when attempts to teach using audition have failed should teacher employ touch or vision

“Speech and the Hearing-Impaired Child: Theory and Practice” Ch. 13 Teaching Strategies Related to Vowel Production –“Before strategies involving primarily touch and vision are adopted, the child must first have abundant spontaneous vocalization and elementary control of voice patterns….too often we see teachers who have not made exhaustive efforts to exploit residual hearing, have not provided regular and plentiful auditory models, and have not given appropriate reinforcement for vocalizations varying in phonetic quality.” p.231 –Failure to optimize natural speech development may “critically and permanently impair the child’s attitude toward speech communication”