Resonance disorders and Velopharyngeal Dysfunction

1. Resonance disorders and Velopharyngeal Dysfunction March 2, 2015

2. Introduction • Resonance – modification of sound produced by the larynx through selective enhancement of certain frequencies • The size and shape of the vocal tract has an impact on the individual’s speech, resonance and overall voice quality • Vowel sounds are differentiated by the change in the shape of the oral cavity with the tongue position which changes the formant frequencies • The vocal tract is a 3 dimensional resonating tube that is highly modifiable • Changes shape and size during speech due to the action of the hyoid muscle group • Larynx, pharynx, mandible, tongue and velum attached to the hyoid by musculature and movement of one of the structures results in movement of others • Height of the velum and configuration of the pharynx are affected by tongue position • Changes the resonance which has an effect on how sound is perceived

3. Introduction • Effect on pitch (higher pitch the larynx raises to shorten the pharynx) lateral walls contract to create a very narrow pharyngeal tube (blowing across a bottle) • Children with a short pharynx have higher resonating frequencies • Males and females differ on oral cavity sizes and perception of vocal quality • Anything that changes the length or shape of the resonating cavities affects the quality of the voice • Changes in pharynx due to palatoplasty surgeries (pharyngeal flap can shorten the resonating tube causing a change in resonance) • Velopharyngeal valve is responsible for directing sound energy and airflow from the pharynx into the oral cavity for oral sounds and nasal cavity for nasal sounds • Needs to be completely closed to direct sound energy anteriorly into the oral cavity and open for the production of nasal sounds and nasal breathing

4. Resonance disorders and VPI • Resonance disorders (hypernasality) are labeled inappropriately as voice disorders • Not laryngeal in origin – resonance disorders more appropriate classification • Structure and balance of sound energy in the cavities determines whether the quality of speech or voice is perceived as normal or deviant • Anything that disrupts the transmission of sound in the cavities of the vocal tract will cause abnormal resonance • Obstruction • Oronasal fistula • Velopharyngeal dysfunction

5. Resonance and velopharyngeal dysfunction • Velopharyngeal dysfunction refers to • the velopharyngeal valve does not close consistently and completely during production of oral sounds • Velopharyngeal valve does not open completely during the production of nasal sounds • General term when etiology is not specified

6. Resonance and velopharyngeal dysfunction • Several controversies about terminology • Velopharyngeal insufficiency – anatomical or structural defect that prevents adequate velopharyngeal closure (short velum common after cleft palate repair) (7-1,2) • Velopharyngeal incompetence – neurological or physiological disorder that results in poor movement of velopharyngeal structures (7-17-20) • Velopharyngeal mislearning – inadequate velopharyngeal closure due to secondary or faulty development of appropriate articulation pattern (7-21-23) • No specific etiology velopharyngeal dysfunction is used

7. Hypernasality • Abnormal coupling or sharing of acoustic energy between the oral and nasal cavities • Often described as muffling or mumbling • This is due to dampening of sound effect or sound absorption • Associated with sounds that are phonated especially vowels and not substituted with another placement • Noted more on high vowels than low vowel sounds • High tongue reduces oral resonance space and causes partial impedance of sound through the oral cavity • Increase in sound pressure results in an increased transmission of sound through the velum • If the velum is thin this adds to the hypernasality even in the absence of a insufficiency

8. Hypernasality • Mild to moderate hypernasality causes nasalization of oral phonemes (7-14) • Velopharyngeal valve remains open during the production of a voiced plosive, the result will be the nasal equivalent of the sound (m/b or n/d or a/g) • Nasalization can occur on other oral sounds (substitution of other voiceless sounds) • Predominance of /m/, /n/ and /a/ in connected speech

9. Hypernasality • Cause is mainly velopharyngeal insufficiency but it could be velopharyngeal incompetence • Nasality perceived with larger openings and not smaller ones or a large enough oronasal fistula • Hypernasality due to velopharyngeal mislearning is phoneme specific or involves substitution of particular phonemes with nasal sounds (a/l or a/r) (7-21, 22, 23) • Should not be confused with a nasal twang which is dialectal

10. Hyponasality and denasality (7-3) • Hyponasality occurs due to a reduction in normal nasal resonance during speech due to blockage in the nasopharynx or nasal cavity • Sounds “stuffed up” • Denasality is used to describe total nasal airway obstruction and resultant effect on resonance • Impossible to know where the blockage is through perceptual assessment alone the term hyponasality is used • Affects production of nasal consonants (/n/, /m/ and /ŋ/) • Open mouth posture, mouth breathing, loud snoring and sleep apnea • Common cause swelling of the nasal passages secondary to allergic rhinitis or common cold, adenoid or tonsillar hypertrophy

11. Hyponasality and denasality (7-3) • Medical or surgical intervention • Can occur due to apraxia or faulty coordination of the velopharyngeal movements with anterior articulation and the velum does not lower rapidly enough for nasal phonemes once it is raised for oral sounds • Hyponasality common in individuals with cleft palate especially in adolescent speakers as a complication of surgery • Another cause may be a deviated nasal septum (unilateral clefts) or stenotic nares or maxillary retrusion which restricts nasal cavity space • Apert, Crouzon’s and Pfieffer syndromes may all involve hyponasality

12. Cul de sac resonance (7-4) • Occurs due to obstruction or when transmission of acoustic energy is blocked or trapped in a blind pouch with only one entrance and no other outlet • Speech is muffled (potato-in-the-mouth speech) • Very large tonsils that block the oral cavity and vibration occurs mainly in the oropharynx • Sound quality is muffled with low intensity (sound absorbed by the pharyngeal tissues) • Can occur due to scar on the pharyngeal wall in the hypopharynx • Common in children due to VPI and blockage of the nasal cavity due to deviated nasal septum

13. Cul de sac resonance • Simulated by producing a series of nasal phonemes (ma, ma, ma) while pinching the nose • Because sound energy cannot be released through the nares it is trapped in the nasal cavity • Pinching the nose during simulation of hypernasality does not result in oral resonance because the blockage is at the front of the nasal cavity and not in the area of the velopharyngeal valve • Cul-de-sac here is typical of nasal polps, deviated nasal septum or stenotic nares • Cul-de-sac resonance is due to structural anomaly (blockage of one of the resonating cavities) • Requires medical or surgical attention

14. Mixed resonance • Combination of any of the types of resonance • Hyper and hyponasality cannot occur together they can occur at different times in connected speech of the same individual • Common in individuals with apraxia due to inappropriate timing of the upward movement of the velum on nasal sounds and downward movement on oral sounds • If there is velopharyngeal insufficiency in addition to blockage in the nasal cavity, the predominant characteristic of connected speech is hypernasality with hyponasality during the production of nasal consonant sounds • If the blockage is lower in the pharynx and fairly large the most notable characteristic is hyponasality

15. Mixed resonance • Some individuals may demonstrate hyponasality and nasal emission (same cause as hypernasality) • Does not occur simultaneously but on different speech sounds • Common cause is enlarged and irregular adenoid tissue • During production of oral sounds the velum closes against the adenoid pad but a tight velopharyngeal seal cannot be maintained due to irregular adenoid tissue resulting in nasal emission • When the velum goes down for production of nasal sounds the adenoid pad is large enough that it obstructs the transmission of sound into the nasal cavity causing hyponasality

16. Other effects of velopharyngeal dysfunction on speech • Nasal air emission (7-05) • Occurs when there is an attempt to build up intraoral pressure for production of consonants in the presence of a leak in the system (velopharyngeal valve or oronasal fistula) • Some of the airflow is released through the nose which causes a disruption in the aerodynamic process of speech • Noted mainly on pressure sensitive phonemes (plosives, affricates and fricatives)

17. Other effects of velopharyngeal dysfunction on speech • Does not occur during the production of vowels or semivowel because there is not need for a build up of air pressure • Can occur with hypernasality or with normal resonance • Can be very loud and distracting or very soft and barely audible or it can be inaudible depending upon the size of the opening

18. Other effects of velopharyngeal dysfunction on speech • When there is a large opening there is little resistance to the flow with significant loss of air pressure through the nose which is not very audible due to minimal amount of friction • When there is a smaller opening there is greater resistance to the flow which makes nasal emission more audible • When the opening is very small the resistance causes the airflow to become turbulent as it passes through the valve

19. Other effects of velopharyngeal dysfunction on speech • The air is released on the nasal side of the opening with great deal of pressure which causes bubbling of nasal secretions (seen on nasopharyngoscopy) or through a videofluoroscopy when there is coating of barium (nasal turbulence) • Some prefer to call it a nasal rustle (7-05) • Nasal congestion can make this distortion even more noticeable

20. Other effects of velopharyngeal dysfunction on speech • Nasal air emission (7-05-09) • A nasal rustle can be very loud and distracting, masking the sound of the consonant affecting sound quality and intelligibility (7-08) • Voiceless fricative are most often distorted by nasal emission or a nasal rustle due to more air pressure than their voiced counterparts where the adduction of the vocal folds attenuates the air pressure somewhat (7-09) • Nasal emission due to VPI occurs on all pressure sensitive consonant sounds (/s/, /z/, /c/, /x/, /./, /j/) (7-07)

21. Other effects of velopharyngeal dysfunction on speech • If it is only on /s/ then it is probably due to faulty articulation or velopharyngeal mislearning rather than VPI because there is complete closure on all other sounds • Phoneme specific nasal air emission (PSNAE) occurs mostly commonly when the individual uses a posterior nasal fricative as a substitute for sibilants resulting in elimination of nasal emission

22. Other effects of velopharyngeal dysfunction on speech • Nasal grimace (7-06) • Accompanies significant nasal emission • Can be seen as a muscle contraction just above the nasal bridge or at the side of the nares (same as a muscle contraction when someone is trying to lift something heavy) • Overflow muscle reaction that occurs with extreme effort to achieve velopharyngeal closure • Once velopharyngeal function is corrected this usually disappears

23. Other effects of velopharyngeal dysfunction on speech • Weak or omitted consonant sounds (7-08) • When air flows through the velopharyngeal valve or oronasal fistula it reduces the amount of air pressure that is available in the oral cavity for the production of consonants • Causing the consonants to be weak in intensity and pressure or omitted completely • Direct inverse relationship between amount of air nasal emission and the pressure for production of oral consonants

24. Other effects of velopharyngeal dysfunction on speech • Greater the nasal air emission the weaker the consonants will tend to be • Weak consonants are expected primarily with the unobstructed form of nasal emission because there is more airflow through the nasal cavity • They also cause in addition to nasal emission or hypernasality speech to be muffled and indistinct

25. Other effects of velopharyngeal dysfunction on speech • Short utterance length (7-09) • When there is significant nasal emission due unobstructed opening it causes a decrease in oral air pressure for connected speech • More frequent breaths required for replacing air pressure • Utterance length is shortened and connected speech is choppy • Individuals with large velopharyngeal opening raise intraoral pressure by increasing airflow rate during consonant production • They produce respiratory volumes that are twice that or normal speakers • Makes speech difficult and causes fatigued during speech production

26. Other effects of velopharyngeal dysfunction on speech • Altered rate and speech segment durations • Using spectrograms to measure segments, it was found that children produce longer segment duration • Longer voice onset timings • Due to increase respiratory effort and frequent breaths to compensate for rapid loss of air pressure through nose • Suggest that coordinating speech production in the presence of a malfunctioning velopharyngeal valve is very difficult • Affects the overall rate of speech

27. Other effects of velopharyngeal dysfunction on speech • Compensatory and obligatory articulatory productions • Above mentioned are passive speech characteristics or obligatory errors caused as a direct result of structural abnormality of velopharyngeal or palatal opening • Articulation production that are not the direct result of velopharyngeal dysfunction but are the individual’s response to this dysfunction are called active speech characteristics or compensatory errors • Compensatory errors are often developed by the individual as a response to inadequate intraoral pressure for normal articulation

28. Other effects of velopharyngeal dysfunction on speech • When compensatory productions are used the manner of production is usually maintained • Place of articulation is altered and moved posteriorly to the pharynx or larynx before it is reduced because of the velopharyngeal opening • Compensatory movements are under the control of the individual and therefore can be modified with speech therapy • Obligatory movements are the direct result of abnormal structure and require surgical or prosthetic intervention for correction

29. Other effects of velopharyngeal dysfunction on speech • Middorsum palatal stop (palatal-dorsal production) (7-15) • Stop consonant that is produced with the dorsum of the tongue against middle of the hard palate • The production is substituted for the lingual-alveolar sounds (/t/, /d/, /n/ and /l/) and velar sounds (/k/ and /g/) • Place of production is between that for lingual alveolars and velars • Boundaries for distinguishing the two placements are lost and the result sound like a cross between the two placements • A palatodorsal placement will also be used for the productions of sibilant sounds (/s/, /z/, /sh/, and /zh/, /ch/ and /y/) • This results in a lateral lisp

30. Other effects of velopharyngeal dysfunction on speech • Usually a obligatory strategy but can be a compensatory strategy due to overcrowding in the anterior oral cavity due to class III occlusion or anterior cross bite (maxillary teeth are positioned behind the mandibular teeth) • The alveolar ridge is behind position of the tongue tip • The individual compensates for the relative anterior position of the tongue by pulling it back • As the tongue retracts and goes down the dorsum goes up to articulate against the alveolar ridge or the palate • Can be also seen in individuals with macroglossia • When there is a midpalatal fistula, the individual uses this movement to occlude the fistula and just preventing nasal emission

32. Other effects of velopharyngeal dysfunction on speech • Generalized backing • Some individuals will articulate with posterior articulation of other oral sounds • Using velar sounds as a substitutions for anterior sounds • In cases the anterior sounds are actually co-articulated with the velars where the plosive is actually produced • Posterior articulation allows the individual to impound air pressure in the back of the oral cavity • Back of the tongue can help to push the velum upward to assist with closure as a compensatory strategy for VPI

33. Other effects of velopharyngeal dysfunction on speech • Velar fricative • Produced with the back of the tongue in the same position as for the production of a /j/ sound • With the back of the tongue elevated and positioned under the velum a small space is created • The velar fricative is produced as air is forced through the small opening • The velar fricative may be substituted for any fricative sound but is most commonly substituted for a sibilant • It can be voiced or voiceless • Difficult to distinguish from a pharyngeal fricative but with good diagnostic techniques the source of the fricative can be located

35. Other effects of velopharyngeal dysfunction on speech • Nasalization of oral consonants (7-14) • Obligatory error due to an open velopharyngeal valve • When the valve remains open during production of voiced plosives the acoustic product will sound like their nasal counterparts • In this case the placement of the phoneme is preserved but the manner is changed from an oral to nasal due to the open velopharyngeal port • Nasalized phonemes are usually associated with the presence of hypernasality as a result of a large velopharyngeal opening

36. Other effects of velopharyngeal dysfunction on speech • Nasalization of vowels • High vowel sounds have more nasal resonance than low sounds • High tongue position causes more acoustic impedance than the open oral cavity of a low vowel sound • Due to the constriction there is increased pressure above the high point of the vowel • There is likely more transpalatal transmission of sound energy through the velum

37. Other effects of velopharyngeal dysfunction on speech • Some children with a history of cleft raise the back of the tongue too high so that it actually articulates very close to or against the velum • This blocks the sound from entering the oral cavity and forces it to travel through the nasal causing nasalization • Even for those without a history of a cleft can demonstrated phoneme-specific hypernasality due to a high tongue position on high vowels • Although velopharyngeal closure may be normal during the production of consonants on nasopharyngoscopy the resonance can be perceived as hypernasal due to increase in oral impedance on high vowels

39. Other effects of velopharyngeal dysfunction on speech • Nasal snort • Is produced by a forcible emission of air pressure through the nose that results in a noisy, sneeze-like sound • The sound is typical associated with /s/ blends • It often occurs with a nasal grimace • May be an obligatory error and occurs with nasal emission a compensatory error due to mislearning

40. Other effects of velopharyngeal dysfunction on speech • Nasal sniff • Is not a common compensatory articulation production but it also occurs • The phoneme is produced by a forcible inspiration though the nose • This is an opposite of nasal emission • Usually substituted for sibilant sounds particularly /s/ • Due to difficulty in coordinating the inspiration and expiration during articulation with /s/, it typically occurs only as the final word position rather than in all word positions

41. Pharyngeal plosive • Is a consonant that is produced with the back of the tongue against the pharyngeal wall • During the production of the sound the dorsum of the tongue is convex in configuration and low in the oral cavity • The entire tongue moves posteriorly in order to articulate against the posterior pharyngeal wall and used the air pressure that can be established in the pharynx • An increase in pharyngeal activity can be noted by observing the throat area • Due to difficulty of producing this phoneme there is often a longer duration between the consonant and the following vowel • Pharyngeal plosives can be voiced or unvoiced • Although they can be substituted for other consonant sounds they are typically substituted for the velar plosives • Glottal stops usually substituted for other consonant sounds because they are easier to produce

43. Pharyngeal fricative (7-15) • Another consonant that uses the back of the tongue and pharynx • It is produced when the tongue is retracted so that the base of the tongue approximates but does not touch the pharyngeal wall • A friction sound occurs as the air pressure is forced through the narrow opening between the base of the tongue and the pharyngeal wall • Can be substituted for fricatives and affricates and sibilant sounds (/s/, /z/, /c/, /x/, /./, /j/) • Can be voiced or voiceless (unvoiceless more common) • Can sound similar to a lateral lisp

45. Pharyngeal affricate • Same placement as a pharyngeal plosive and fricative • Can be difficult to distinguish from a fricative specially in connected speech • Combination of a pharyngeal plosive and fricative • An increase in pharyngeal activity can be noted in the throat area during speech • Typically substituted for /./ and /j/ sounds although they can be substituted for other sibilants /s/, /z/, /c/ and /x/ • They can be voiced and voiceless

46. Posterior nasal fricative (7-23) • Misarticulation characterized by audible nasal emission and friction in the posterior nasal pharynx • During production the back of the tongue is often up and articulating against the velum as in /a/ placement • Because the tongue blocks the entrance into the oral cavity air is forced through the velopharyngeal valve • A posterior nasal fricative can be seen on a videofluoroscopy or through a nasopharyngoscope as an incomplete closure of the velopharyngeal valve

47. Posterior nasal fricative (7-23) • The nasal emission is perceived as a nasal rustle • The posterior nasal fricative can be a compensatory articulation production of VPI or it can be a learned misarticulation that results in phoneme specific nasal emission • The posterior nasal fricative may be used as a substitute for any of the pressure sensitive phonemes but it is typically used for sibilants particularly /s/

49. Glottal stop (7-11-13) • Plosive sound that is produced with a forceful adduction of the vocal folds and ventricular folds (false vocal folds) • There is a build up of subglottic air pressure and then sudden separation of the true and false folds to release the air pressure and create airflow • Grunt sound seen in the throat area as increased laryngeal activity • Substituted for plosive sounds but also for fricatives and affricates especially if these are not yet developed • Perceived as a voiced phoneme because its production results in rapid voice onset for the vowel

50. Glottal stop (7-11-13) • Unlike other compensatory productions it can be coarticulated with other phonemes • Two places of valving • Visually appears as if the individual is producing the sound correctly with appropriate oral placement even though the plosive production is actually in the glottis • Because the closure is in the glottis there is no need for velopharyngeal closure so glottal stops often appear to be associated with a significant velopharyngeal opening