The Use of the Aerophonoscope for Assessing Velo-Pharyngeal Incompetence and Therapeutic Decisions

: Aerophonoscope is an ultra sensitive and original instrument for detecting nasal airflow and analysing the Velo-Pharyngeal Sphincter –VPS - movements. It reveals the aerodynamic function of the VPS, in the usual conditions of speaking and breathing. It has been created for patients with facial cleft, of 4 years old upwards, after primary surgery and during their growth, in a harmless, non-invasive way. There are several sorts of assessments of Velo-Pharyngeal Incompetence (VPI): from an anatomical point of view, a perceptive, acoustic, aerodynamic one. The Aerophonoscope belongs to the latter one . We know the difficulties to treat this pathology in the fields of surgery and speech therapy mostly because of misunderstanding VP physiology and physiopathology, which are complex. Then aerophonoscopy allows us to understand this complexity. So we are able to easily assess excessive Nasal Loss -NL- factors. The NL is linked mainly with a VPS persistent lack of closing, of course. But it varies according to its stiffness, tonicity, and its smaller and slower movements. The latters are according to each phoneme or syllable, and they have more or less speedy succession of the “phonological verbal chain”. So we aim at presenting this instrument that enables an aerodynamic assessment of the VPS precisely. We can analyse many characteristics of its pathological movements with different tests in our protocol (passive, active, effort, successive movements and so on) and show the results of about 652 individuals. These data contribute to guide therapeutic decisions, (choice of type of surgery, targets of rehabilitation), such as to restore the VPS physiology at the very most. Furthermore, it provides a pleasant and efficient means of rehabilitation of the VPS


Introduction
Velopharyngeal incompetence is divided into 2 groups: 1) Closed rhinolalia which excludes the contribution of nasal resonance cavities, and so induces hypo-nasality, which is not dealt with in our study. 2) Open rhinolalia which, on the contrary, induces hypernasality and has different etiologies. Mainly, we can differentiate between: a) Major dysmorphic damage (bony and soft cleft palate), treated early with primary surgery, but the incompetence may persist, requiring secondary surgery of the velopharyngeal neosphincter. b) Minor rhinolalia, discovered at the age of about 2 to 5 years old in the context of speech delay, especially with genetic etiology +/-accompanied with hearing, psychological, neuropraxic and cognitive disorders. The word "rhinolalia" usually means only acoustic and phonetic data, but in this study, we shall use the aggregate term, "velopharyngeal incompetence" from different aspects, aerodynamic, acoustic, phonetic and anatomic ones.
Among the present means, the AERO-D aerophonoscope enables the examination of velopharyngeal aerodynamic function in physiological conditions of speaking and breathing, without intimidation.
With a cohort of 652 subjects, it enabled us to discover different types of velopharyngeal incompetence and led us to choose the best surgical and rehabilitation treatments, and to assess the effectiveness of these treatments. In French, the opposition between oral and nasal phonemes is important.
It opens up new research perspectives.

Method and Material
Equipment: The aerophonoscope was created in Nantes in the 1980's, by a speech therapist named Brother Pascal Rineau [1] and Professor Jean Delaire [2], who was a maxillo-facial surgeon. It can record nasal and oral air flow, by using original sensors in the physiological conditions of speaking and breathing without scaring the child, and is thus easy for children from 3 and a half to 4 years old. It may be used with a laryngeal microphone.
This equipment is composed of 3 sensors connected by a USB port to a computer, on which the AERO RD program has been installed. These sensors have thermistors, which are platinum wires, heated to 100°C by an electric current, and cooled by the air expired by the patient: the air flow cools the hot wires according to its speed.  Thus, even minimal nasal air loss can be quickly and reliably detected for a given group of phonemes or syllables and their sequences, according to the physiological conditions of speech. This ultra-sensitive detection is easily reproducible. [31] The mouth sensor is a placed at a distance from the lips so as not to prevent them from moving spontaneously, therefore it can only detect a part of the buccal air flow, which is impossible to measure precisely in children.
The nasal air flow sensor matches the shape of nostrils as closely as possible.
It allows a sensitive and objective record of nasal air flow (NAF) and therefore shows 4 physiological facts: 1) spontaneous nasal ventilation (at rest, in speech or whistling), 2) the detection of any variations of Nasal Air Flow in speech; (Marshall [3]) 3) Characteristics of closing/opening movements of the velopharyngeal sphincter (VPS) all through the alternate sequences of oral/nasal syllables: their closing competences, their amplitude and stiffness, their speed, their steadiness (according to accelerations, prosody of speech, etc.), 4) Voice-velum coordination, during the pronunciation of voiced or unvoiced consonants. The latter notions are the topic of another study. These nasal and oral air flows are shown with 2 proceedings:

A Screen with a Child's Face
Whose nasal and buccal ports are colored.

A Screen with 2 Main Lines
An upper one, for the nasal airflow, and a lower one, for the buccal air flow,--which is partially detected and so not interestingor for the laryngeal tune. 2 vertical lines represent 1sec.
No nasal loss for a sentence composed of oral sounds, in French.  On this curve we must observe the alternate rise and fall of the nasal flow line, linked with the up and down movements of the velum, linked to the sequences of Nasal syllables/Oral syllables: Here the nasal line shows: 1) The complete velopharyngeal closing, when the curve joins the base line on /a/. 2) the maximal amplitude of velopharyngeal opening during the ascendant peaks on the nasal syllable /non/ 3) the variations of the speed of these movements: a) High declivity = nasal flow acceleration b) Minor declivity = nasal flow deceleration, very slight here These 2 syllables (a/non) are very contrasted, according to nasality feature.
NB. On the right of the curve, the sphincter inertia does not allow the complete closing between two nasal syllables. The aerophonoscope confirms notice a physiological co-articulation of oral/ nasal syllables (contamination phenomenon), beyond a given speech rate level (beyond three syllables per second here): the base line is not reached for the pronunciation of /a/ in the case of healthy individuals.

A Reminder of Velopharyngeal Sphincter Physiology in Phonation
The velopharyngeal (VP) sphincter is a muscle of articulation, which plays a very important part in speaking, giving phonemes their oral or nasal character for the voice tone [1].
The phonological opposition between "oral sounds" and "nasal sounds" is achieved through velar elevation and pharyngeal muscle constriction (for oral sounds) as opposed to velar lowering and pharyngeal muscle release (for nasal sounds), with the irregular participation of the palato-glossus [5]. The main muscle of the soft palate is the levator palatini muscle (LP) whose movements (contrary to expectations) are very fast [6], even if there is some velar inertia in the transitions between oral and nasal sounds. And this inertia explains different acoustic phenomena (variations of formants, phenomena of anticipation and spreading of the nasality [4]. It remains active in speaking.
In pathologic situations, velar incompetence is characterized by:

On an Aerodynamic Level
The nasal airflow is related to different factors: 1) Of course, to the VPS impedance, its ability to close, in other words, its role in "resistance" against nasal flow [7,8] Warren]. 2) This is correlated to the intra-oral pressure, and so to the buccal orifice and to the labialization or not of the oral or nasal vowels [9]. 3) To the recoil of the tongue [10]. 4) To the buccal orifice (Amelot [11]) for healthy individuals, there is an opposition between the oral open and closed vowels: the latter require a small buccal orifice correlated to a higher intra-oral pressure, inducing a greater oral airflow than for the open vowels. We can observe the same fact for pathological individuals with cleft malformation. 5) The fact that excessive "nasal loss" (NL) sometimes exists with means of compensation: narrowing of nostrils, laryngeal and pharyngeal constrictions.

On an Acoustic Level
The feature of nasality of the sounds /an/on/in/un/ is characterized by the existence of counter-formants and by changes of the frequency, intensity and bandwidth of some formants (in particular F1 and F2) in comparison with those of the oral vowels [a/o/e/eu] [9,10]. In pathological situations, the excessive nasal resonance is called hypernasality with or without additional noises (nasal blow and ronchi). Sometimes both hypo-and hypernasality are noticed.
In 2 recent studies, the "Diadolab" software allows a precise spectral analysis, with an easy mean of vowels segmentation in the phonological chain: the counter-formants or the "counter-resonance", have peculiar characteristics in the F1, F2, and in the zone F3-F4, above all for the opposition /è/in/ and /a/an/ (Sicard and al. [12]). In a second study, we tried to highlight the distinctive features of oral and nasal vowels in terms of the frequency variation of the formants, and their respective energy [13].

Three Important Phenomena
About velo-pharyngeal physiology must be noticed:

Velar Inertia
There is a slowness in transitions between nasal and oral sounds which are explained by the following fact: nasal vowels have 2 segments: the first segment has no NAF, then in the second one, the nasal air flow appears; these vowels are produced and perceived as diphthongs (Montagu, 2004; cited by A. Amelot [11]., Ohala [9], [Demolin [14], Delvaux [15] Skolnick [16].
During the pronunciation of nasal sounds, there is a moment of maximum opening of the soft palate, where we have a good perception of nasality, especially for the nasal vowel /on/, which is prioritized in our assessment tests.

The Phenomenon of Co-articulation
For healthy individuals, most of the time, there is a coarticulation of nasal and oral phonemes: a nasal air flow for the oral vowels exists to varying degrees in every language, as Durand described [17] in 1954, then Basset [18]. In other words, a tolerable physiological margin exists for oral sounds. This small level of opening of the velopharyngeal sphincter induces a nasality in different ways for different vowels (quantified exactly at 0.4 cm 3 for /i/; 1.6 cm 3 for /a/) Vaissiere [19].
The feature of nasality is not reducible to the binary description (oral sound = tight sphincter, nasal sound = permeable sphincter, as defined by Chomsky (1968 Thus, there are different levels of activation of the LP (levator palatini) according to each phoneme. Usually, the following order is found, beginning with the phonemes which facilitate the closing of VPS (the most "resistant" to hypernasality) to the least facilitating ones (the least resistant).
A different order will be observed in this study in pathologic situations, mainly in dysmorphic disorders.

The Striking Phenomenon of Contamination
May be considered as an exaggeration of the phenomenon of nasal co-articulation, varying in audibility in different languages (for instance, French requires a high phonological opposition between oral and nasal sounds.) This contamination may occur before the production of nasal phonemes (anticipation nasality) or after the production of nasal sounds (spreading nasality) [11]. For instance, in the French word "donc", the first and the last phonemes are nasalized.
It also depends on different factors: speed and acceleration of speech, accents of intensity, prosody (melodic rise for interrogative and exclamatory formulations, and melodic descent for affirmative formulations.) which are important to assess.
These phonotactic facts are part of the notion of "phonetic context" House [22], Delvaux [23], Kent [24]. For this healthy person, we observe the fact in the right part of the curve: the base line is not reached during the /a/ productions, beyond 3 syllables /sec. N. B. We know the particular case of singing voice: 1) The singing formant is produced mostly by raising the soft palate (Levator palatini and Tensor palatini) and by the enlargement of the naso-and oropharynges (Durand) [17]. 2) Furthermore, the high-pitched notes induce a spacing of harmonics and formants, which modify the spectrum and the perception of all oral and nasal sounds (Benguerel) [25], which are not easily recognized.

Aim of Our Work
Aerophonoscopic assessment, focused on the dynamic movements of the pathological VP sphincter, has been conceived in a surgical perspective for the best correction possible of the considerable nasal air flow (NAF), peculiar to the residuals of cleft palates, and all sorts of velar incompetence; and to restore the best kinetic capacities, in order to realize good phonological opposition between nasal and oral sounds.
Surgery and rehabilitation by speech therapists have to consider all the factors of velopharyngeal incompetence.
The quality of closed/open movements of the velopharyngeal sphincter depends on many factors, which explain the variability of articulatory, aerodynamic and acoustic data. These data are not linear in healthy people nor are they in pathological ones.
These factors are ranked according to their importance:

Anatomical Factors
1) The degree of lack of closing, which depends on the length of the soft palate and the width of the naso-pharynges.
2) The flexibility of tissues (surgical after-effects, velar retraction after tonsillectomy, etc.) The increase of nasal airflow (NAF) rate depends on the pressure gradient between oral and nasal cavities, which vary according to each phoneme and syllable.

Dynamic Factors
The opening amplitude, the speed of closing/opening movements, the presence of phonotactic contaminations depend on several things: motor characteristics of each phoneme and syllable, melokinetic praxis capacities, stiffness, tongue recoil, means of compensation of speech disorders (for example lingual, pharyngeal, laryngeal muscle syncinesis by full contraction of the Deep Facial Muscular Chain -Delaire 75-).

Linguistic Factors
Requirements of the language and phonatory behavior, for healthy or pathological people:

A Nasal Co-articulation
That is to say, a tiny connection between oral and nasal cavities by a slight velo-pharyngeal incompetence, audible to varying degrees, and variable in different languages; it is very slight in French [5].

Proportion Nasal Oral
The proportion of nasal sounds alternating with oral sounds, which is one of the characteristics of continuous speech, of "phonological chain" (Jakobson), It exists with varying regularity and is different in every language.

Prosodic Variations
Strength of stress accents (of tone and of intensity), characteristic for each language -speed rate and acceleration of an individual's speech ("tempo") induces a decrease of movement speed and so an increase of the phenomenon of contamination. (Abudoueh [25]) All these factors must be examined to assess the severity of the VP incompetence. If these tests are not made, this leads to a wrong assessment and gives "false negative" data.

Neuromuscular Factors
1) Flabby paralysis, organic hypotonia, myasthenia; dystonia linked or not with genetic disease; 2) Functional hypotonia by the absence of auditory feedback, cognitive deficiency, immaturity. 3) "Verbal Dyspraxia" ("childhood apraxia of speech") and Kinesthetic Afferent Dyspraxia, involving more elaborated cognitive linguistic processes (Dewey) [28]. The 3 latter factors are assessed, in particular, with the specific called "sensitization" tests during the examination using an aerophonoscope.

Examination Protocol
Preliminary: in this paper, we'll use more the common alphabet notation, than the international one, such as to be easy to read, except in appendix.

Main Lines
The examination by aerophonoscope includes 3 different tests: 1) Passive movement tests: with oral expiration: continuous and pulsated blow, in order to assess the soft palate scar stiffness: oral expiration increases intraoral pressure leading to passive rise of the velum. 2) Active movement tests: to assess the closing capacities according to the different types of vowels and syllables. a) From the more facilitating ones: open vowels [a/è/o/] associated with [/p/t/k/] in words or little syntagms: "t'es pas cap", "take up" (see examination protocol in English) b) To the less facilitating ones: closed vowel associated with [/v/z/j/]: "Jue view a zoo", "jé vu zizou". 3) Sensitization tests: to assess the muscular efficiency, more than pure scar stiffness a) Above all, tests of alternative up and down soft palate movements --and pharyngeal constriction--, to assess the speed of the up and down movements and the inter-syllable contaminations between nasal syllables and oral ones, (oh /non, ah /non for instance). In French, we may use oral syllables including an [o]: this vowel which has a medium resistance against hyper nasalisation. b) Basic and action tone: steadiness and effort exercises: scansions (staccato ho! ho! he!), crescendos, glissandos with the velar gesture of « coperto » (by mobilization of the muscular cervical chains), and slow rhythm, then at the rhythm of French, then faster and faster. Now, we will give detail more precisely for these 3 sorts of tests.

Passive Movements Tests
They allow us to evaluate the nasal ventilation in sitting or sleeping positions.
At rest, we observe the spontaneous inspiration and expiration. This permits to detect the varying degrees of obstruction of the nasopharyngeal system and its consequences in the situation of SAS (Sleep Apneic Syndrome) and the situations of tongue protraction, with the impact on swallowing, malocclusions, cranio-facial development. The oral breath increases the intra-oral pressure, leading to the passive rise of the velum.
1) During continuous oral breath, NAF detection is in proportion to the extent of velopharyngeal incompetence, 2) During pulsated oral breath, a NAF detection is determined by the stiffness of the velum due to scarring, for example, or by the speed of its elevation. Figure 9. Continuous oral blow, with nasal loss.

Active Movements Tests
During the tests of production of oral/ nasal sounds, according to our protocol, we shall indicate for convenience the "nasal syllables" -the syllables containing at least one final nasal vowel, a satisfactory condition to show contaminations; with the preference for the nasal vowel [ɔ] (on): in French which gives greater perception of nasality than the nasal vowels [ɑ], [ɛ], [oẽ] (an/ in/un/ in French) [14].
So, we objectified different phenomena of dissociations:  On this diagram we observe the dissociation between the vowels and the consonants: 1) on the one hand, the nearly closing for open vowels /a/, /è/, /o/ and on the other hand, the opening for the vowels /u/, é/, i/; 2) On the other hand nearly closing for the syllables /pa/ta/ka/, but opening one for the syllables /vi/zi/ji. Karling and al. [30] already observed these 2 dissociations. Further more, we notice a dissociation between plosive and fricative consonants ([p/t/k] and [f/s/ch/], for example).
These tests provide a mean of comparative assessment, based on reproducible tests before and after treatment.

Sensitization Tests
Show the true severity of velar incompetence within continuous speech, according to the specificity of the language and the prosody (accents, intonations and rhythm of speech, in particular).
The tests allow to reveal one or several neurological components. Indeed, their purpose is to objectify the mechanisms of the VP sphincter muscles: 1) their steadiness by the study of basic tonus with a continuous sound: 2) their tonus of action, which can be weakened in the tests of effort (with hypertonic movements) 3) These tests also assess the stiffness of musculoaponevrotic structures. 4) Their speed of action and flexibility, by the test of accelerated pace, during the succession of nasal/oral syllables. Thus, their muscular potential and not only the level of nasal air loss.

Steadiness (Figure 12) or Unsteadiness (Figure 13)
Of velopharyngeal muscles (basic tonus) by the test of holding on a nasal vowel /on/, or a distorted vowel (/i/, /u /). On this diagram we objectify: -a steady line by holding on /i/ with constant loss, then the improvement by means of "staccato" (repeated and stronger /i/.). The poor steadiness of their base or action tonus evokes a neurological disorder such a dystonia or coordination or praxis disorders Figure 14. In this case of "Verbal dyspraxia" ("childhood apraxia of speech").
We notice that the first three sequences "/a/mon" are regular, but the following ones are inconstant slowly and speeding up.

Their Tonus of Action
Which is assessed with the effort tests: 1) Accents of intensity: we ask them to make the staccato /hi / /hi //hi / hu /hu/ hu (Figure 12 and 15) 2) Pitch accents: we ask them to do a glissando towards high-pitched sounds. We may notice 3 situations: 1) If there is improvement or normalization: it suggests a functional incompetence 2) If there is no improvement: it would indicate either isolated or additional neurological disorder (hypotonia), or scar stiffness 3) If continuous closing: it is a case of hypertonia.

Figure 15.
Here we can observe an effort test with energetic repetition of the phoneme /u/and /i/, stronger and stronger (after 2 inspirations).

Their Speed of Up and Down Alternative Movements
Of the VP sphincter, with the test of successive sequences of Nasal Syllables / Oral syllables (NS/OS) testing its melokinetic praxis, once or twice a second, then in the rhythm of the French language, then more rapidly, if possible.
The phonemes are called "facilitating" phonemes because they favor the active and passive movements of the rise of the velum and the closing of the velopharyngeal sphincter.
The oral syllables contain all the oral consonants of spoken French; they are repeated so as to make vowels almost mute. We must observe: 1) The different degrees of amplitude of the curve, in proportion with the airflow and the width of the nasal port.
2) The speed of these opening/closing movements is assessed by the degree of declivity of the curves. We may observe a slowness of the curve, which indicates a slowness of the VPS closing (see Figure 17).
3) The presence of contaminations (by prolongation of velopharyngeal incontinence) of nasal syllables, containing at least one final nasal vowel, on the following oral syllables, in the following sequences: a) From the most contrasting: for the alternation of oral and nasal vowels /a/an/; /a/on/; /o/on/. For the alternation of Nasal syllables NS / Oral Syllables OS, within French locutions: "Mon/papa; ta-ta-/lon; caca/mion; sa-sa/von; chocho/mons; fai-fai/sons; vo-vo/yons", for young children; "mon/coco, mon/babar, mon/bobo, mon /dodo, mon/garsgars, mon /foufou,…. or within English ones: « time-time, mankind-mankind, same-same, shame-shame and so on". b) To the less contrasting ones, for the alternation of NS/OS containing more difficult vowels (closed ones /i/u/ou): within French words "pi/ment, ti/llons, qui/gnon; bu/vons, di/nons, gui/don; fi/lons, si/mon, chi/gnon; vi/son, ju/ment; ri/ons, or within English ones: «indeed-indeed, been-been, viewing-viewing, on him-on him». On these curves showing the melokinetic praxis in the alternation of Nasal syllables/ Oral syllables, we can observe: On the right of the curve, we can see the phenomenon of contamination during the acceleration of air flow, which is a physiological contamination of oral syllables on the nasal syllables beyond a certain speech rate (beyond three syllables a second here): the base line is not reached for the pronunciation of /a/.
The sphincter inertia does not allow the whole closing of an oral syllable between two nasal syllables. The aerophonoscope confirms the inhomogeneous character of nasal flow within one-third of a second in the usual conditions of speaking (for a healthy subject).
The whole curve of deflection remains rapid, proving a good action tone; contrary to the following case, (figure 17) where we observe the slowness of rise of the velum during the pronunciation of /a/.  These sequences involve more nasality for these oral syllables. Figure 19. In this case of neurological disorders (hypotonia), we notice an increase of contamination from /nan/ to /gè/. Among them: 12 "Verbal Dyspraxia", called "childhood apraxia of speech" (because of bad programming of phonetic sequences, and linguistic ones. (Dewey [28], Forrest [29])

Three Levels of Severity for
3) Specific dystonia: 7

Pure Dysfunctional Disorders: 27
Called "mislearning" disorders, because these individuals have a good potential.

An Aerodynamic Typology
Using an aerophonoscope we objectified the three dynamic types of velopharyngeal sphincter kinetic disorders, correlated with three etiologic frames: Each pure disorder is characterized by the following criteria:     Many children have these mixed types including different correlated disorders: 1) Either by co-morbidity, within genetic syndromes which add dysmorphic damage to neurological disorders++ ("soft neurological syndrome with dyspraxic disorder, hypotonia) and/or deafness of perception, 2) Or by associated factors, which are linked to etiology: velar stiffness by a hypertrophic process (adenoids or tonsils) added to a deafness of transmission; buccal ventilation, swallowing disorders, dental malocclusion, psychological immaturity and dyspraxia disorders. These factors may each evolve independently of each other during the child's development, causing rehabilitation to be more difficult than was initially estimated, and giving the velum variable dynamic possibilities.
Velopharyngeal dysfunction is related to ventilation, Eustachian tube, swallowing and occlusion dysfunctions, as well as maxillofacial development, which increase the severity or the slowness of the rehabilitation. A velopharyngeal disorder requires all these functions to be tested.
During the child's development, one functional abnormality may involve one or several structural pathologies, just as one structural pathology may lead to one or several functional disorders.
We can find,

Figure. 24. Etiopathogneic links between velo-bucco-facial disorders.
Ventilation, tubal, swallowing, occlusion dysfunctions are correlated to velar function and lead to articulation +/-vocal severe disorders. They involve multidisciplinary care and different sorts of speech-therapy.
These correlated pathologies develop in connection with the others, inducing improvements or worsening, sometimes beyond surgery or rehabilitative treatments of the cleft palate.
So, speech therapy may be an illusion, because of the importance of one factor or another, and on the contrary, it may improve one or several factors at some points of development.
For example, some factors (hearing or psychological ones) will disappear around the age of 2-4 years old, or later up to 6 years, on an average, under the influence of their own medical, surgical or rehabilitation treatments. And it "purifies" the dynamic aerophonoscopic type. Their evolution is difficult to realize, and so the surgical choice is delicate.

Concerning the Neurological Disorders
They may present some combinations of syndromes: 1) For instance dyspraxia + dystonia syndromes; 2) Flaccid deficit + ataxic dystonia, 3) Dyspraxia + hypotonia. Differential diagnosis of neurological disorders: This table 3 is linked with the dynamic criteria of dysarthria and dysphonia, described by Darley and Aronson [27]. Among mixed types, and pure neurological disorders, we may notice the very original phonetic and phonological criteria of "Verbal Dyspraxia" or "Childhood apraxia of speech", which are infrequent. They are caused by a bad programming of phonetic sequences. (Dewey [28], Forrest [29]. In this population of 46 children (mean age = 6,2 years old) who present this "verbal dyspraxia", with dysmorphic disorders (34) or pure neurological disorders (12), we found these different peculiar characteristics: 1) Random substitutions of one vowel for another, and/or substitutions of a consonant for another as well = 100% + and thus, amongst them, random and fluctuating inter-syllable contaminations between nasal vowels and oral ones = 54%. These random substitutions lead to very quick sequences of rhinolalia, sometimes open, sometimes closed, sometimes absent.

Contributions of the Aerophonoscope for Therapeutic Decisions
This classification by aerodynamic types is original and contributes to guide the secondary surgery and also to justify the interest or not of speech therapy. It shows the velopharyngeal movements, whatever the residual gap: their amplitude, their speed, (correlated to softness or tonicity), their steadiness and flexibility.
It is important, before making any therapeutic, surgical and rehabilitation decisions, to assess the severity and type of VP incompetence. With the following criteria: 1) The overall quality of intelligibility at the rhythm of the language [5] 2) The aerodynamic velopharyngeal type, assessed by the tests of active and passive movements and sensitization more than the extend of nasal airflow. The surgical correction of these parameters is enabled by the range of different surgeries [34] Naiman, the choice for a given type and by the surgical calendar developed in our Cleft Palate Center [37,38,39,40] Talmant.
Altogether, we have to discuss the following decisions for secondary surgery:

If It Is a Purely Functional Disorder
Only indication of speech therapy, +/-ENT and psychological care, then a reassessment of Nasal Losses (especially the amplitude of closing/opening, and the effort tests).

If It Is a Purely Dysmorphic Disorder
1) with a gap: lengthening surgery (by plasty, and/or muscular transfer (Sommerlad, Intravelar veloplasty [35]; Andrades [36], R Mann [43]; and/or lipofilling, speech therapy; then a reassessment of residual Nasal Losses (especially by effort tests) 2) With stiffness: softening surgery: muscular transfer and Z or Y plasty, with intense speech therapy, then a reassessment of range of movement (especially with tests of passive movements and of sensitization in the sequences of oral and nasal sounds at the rhythm of the language).

If It Is a Purely Neurological Disorder
1) With hypotonia often associated with dyspraxia: muscle transfer surgery, speech therapy, then a reassessment (by the tests of effort, of sensitization) 2) With flaccid deficiency: reconstructive surgery by Orticochea sphincteroplasty or pharyngeal flap these two sorts of surgery may involve a Sleep Apneic Syndrome (SAS), sooner or later, and the sphincteroplasty may be reduced according to evolution and rehabilitation.
Then speech therapy and a reassessment of nasal loss and residual tonus.

If It Is a Mixed Type
With two or three components, the choice is more difficult: 1) Dysmorphic moderate type with a predominant functional component: supervision after etiological treatment or speech therapy (ENT, psychological care), then reassessment of nasal losses by assessment of the amplitude of closing/opening, and effort tests then § 2; 2) Dysmorphic moderate type with a predominant neurological component: (syndromic, e.g. 22q11): surgeries of §3; 3) Severe dysmorphic type with neurological or dysfunctional component: surgeries of §2.

From a Rehabilitation Point of View
The aerophonoscope provides a fun and efficient means of rehabilitation, it enables a visual feed-back of nasal flow, oral flow, laryngeal vibrations, and makes the rehabilitation of all these movements amusing, in particular the velar movements, the rehabilitation of which is considered to be difficult.
It significantly facilitates the control of: 1) Movements of velar closing/opening (nasal sounds versus oral sounds); 2) Start-up control of vocal vibrations (voiced consonants versus unvoiced ones) and indirectly the kinesthetic sensations of the glottic sphincter in synergy with that of the velopharyngeal sphincter, we call the glotto-velar synergy.
3) The mixing of these two neuromuscular controls.

A Classification of the Vowels and Syllables
In pathological situations, we could classify them according to their facilitating power to close the VPS (or their "resistance" against hyper-nasality).
Using the aerophonoscope, we recorded different dissociations, according to their voicing, opening features; plosive or fricative modality, and we noticed:

Concerning the Vowels
Open vowels are more facilitating than the closed ones.

Concerning the Consonants
1) The unvoiced plosives /p/t/k/ are more facilitating than the voiced ones /b/d/g/. Therefore, the syllables /pataka/ are more facilitating than /pitiki/ and /badaga/ 2) The unvoiced fricatives /f/s/ch/ are more facilitating than the voiced ones (/v/z/j/ Thus: the voicing feature influences the nasality feature 3) The liquid /l/r/ and the /ill (= [j]), do not have any rules. Altogether, we may rank this order from more facilitating phonemes to the less facilitating ones: Open vowels < unvoiced plosives < unvoiced fricatives < voiced plosives < voiced fricatives < closed vowels < nasal consonants < nasal vowels.
These data more or less explain the lack of correlation between anatomic and aerodynamic data: The aerophonoscope examinations prove the variability of the nasal air flow -nearly within a third of a secondaccording to each phoneme or syllable type; and the phonotactic links between nasal and oral sounds.

Assessments for Therapeutic Solution
The aerophonoscopic assessment of the pathologic velopharyngeal sphincter movements is conceived, above all, to choose the best surgical solution and the best ways of rehabilitation, in order to correct: 1) The excessive nasal air flow because of the lack of complete closing 2) Its kinetic behaviour and its muscular potential: their incorrect muscle orientation, and so their lack of tone, their stiffness, their speed and their steadiness. Thus, we focused especially on: 1) Aerodynamic data of nasal air flow for oral sounds and not on the proportion (ratio) between nasal and oral airflows, (called "nasalance" in nasometry). The latter don't allow to analyse the characteristics of Nasal Loss in the "phonological chain" of speech. 2) Assessment of contaminations of the nasality feature especially on the oral sounds among nasal sounds in the phonological chain. In the French language, continuous speech is characterized by frequent alternations between oral and nasal sounds. These contaminations conduce mainly to the severity of the pathology.
Furthermore, we didn't choose all the phonemes, to shorten these drills for children and so to analyse the impact of articulation main features (voicing, plosive, fricative features) on the nasality one, besides the rythmo-melodic facts.

Velopharyngeal Incompetence: An Acoustic or Aerodynamic Disorder
According to Amelot [11] we know, for healthy individuals, that aerodynamic data (air flow speed and pressure) for the vowels are more correlated with the acoustic signal (78% of cases), than with the anatomic or articulatory data (42 % of cases), in particular because of velar inertia. Feng (2004), cited by Amelot, and Cohn [42] demonstrated that the importance of nasality is not linked with the nasal airflow extent.

From an Acoustic Point of View
Open rhinolalias are caused by the participation of a nasal resonance cavity beyond a tolerable physiological margin of nasality, for each oral vowel and each oral syllable according to: 1) The amplitude movement and the defect of closing 2) The slowness of closing 3) The acceleration of the speech rate, which depends on our "melokinetic praxia" (Luria)

From an Aerodynamic Point of View
The excessive opening induces an abnormal flow (cm3/sec) which is correlated to: 1) The diameter width of the opening of the velopharyngeal sphincter (cm 2 ). 2) The air speed which is linked with the strength and pressure inside the mouth (Newton/Pascal) and so the sphincter resistance according to individual oral sounds, which facilitate sphincter closing to varying degrees. That is why these oral sounds are called more or less "resistant" to hyper nasality or "facilitating phonemes" for VPS closure. Moreover, according to the hypothesis of A. Amelot [11], the acoustic spectrum of the nasal vowels, in healthy individuals, is modified when there is an airflow variation, i.e. the closing/opening speed variations lead to the phonological oppositions between nasal and oral vowels.
Indeed, the nasal airflow fluctuates continuously: the more the diameter decreases, during the VPS closing or opening, the more the air speed increases.
Beyond Bernoulli's law, the more significant assessment is the following: to show acceleration/deceleration during these dynamic movements. Now, the aerophonoscopic sensors have rightly thermistors which detect the lesser airflow variations, caused by such dynamic movements.
In others words, the severity of a velopharyngeal incompetence is highly measured by the speed variations of these closing/opening movements, during the alternation between nasal and oral syllables, when the latter include the less facilitating syllables (/bi/di/gi/; /vi/zi/ji/).
Thus, acceleration depends here on 3 differentials: 1) air flow (dV) 2) section (diameter width) (dA) 3) speed (du) The latter depend on x (meter) and t (sec). The flow is: These facts are near to the Venturi effect; we could say that when the section is decreasing, the air speed is accelerating, and his time is shortening.

The Phenomenon of Contamination
It betrays also the severity. It results from the "phonological context" (Kent and Winifie [24]). It is easy to detect by means of the called "sensitization" tests. It depends on: 1) The speed of succession of nasal and oral sounds ("mon/day", "man/kind", "prête ton peigne à Clément", "a/non", "mon/papa; "mon/dada", etc.) and it increases in a very significant way, with the slightest acceleration of the speech rate, 2) The proportion of nasal sounds compared to oral ones, in the words or in the sentences, 3) The predominance of facilitating or non-facilitating oral phonemes in the phonological chain, 4) The prosodic variations and inherent accents of the language But we have to pay attention to the fact that there is a tolerable physiological margin of nasal air loss, assessed especially for some vowels and syllables, those we described in pathology as less "facilitating": closed vowels ([i], [u], [y] and the syllables /bi/di/gi/ and /vi/zi/ji/.
This phenomenon of contamination was studied here only at the rhythm of 3 to 4 syllables per second and a regular alternation of nasal and oral syllables in the proportion of 1 for 1. One of our perspectives is to study the other proportions we find in the French and other language phonological chains.
NB: The evaluation of severity of the VP incompetence by Mme Borel-Maisonny concerns only an acoustic point of view with 2 phenomena (existence of hypernasality and 3 levels of articulatory disorders) which are mostly not correlated between them and with the aerodynamic point of view.

What Is the Limit of Speed of Speech Leading to Tolerable Contaminations Between Nasal and Oral Syllables in Pathological or Healthy Individuals
Our hypothesis is three to six per second, for healthy French-speaking adults, with this proportion of 1 for 1. One of our perspectives is to study more exactly this hypothesis for that and other proportions.

Surgical Decisions
Before surgery, we have to consider: 1) The severity of hypernasality and inelegant nasal noise.
2) Above all, the alteration of the muscles'mechanisms, whatever the extent of nasal loss: amplitude and stiffness; speed or slowness of closing/opening movements, unsteadiness of tone, irregularity, inconstancy and difficulties of programming sequences. Among them, the main dynamic parameter to restore is the speed of VP movements in order to give the best phonological opposition of nasal /oral sounds, whatever the extent of the VP gap.
This ambition is possible thanks to a wide range of surgical procedures offered in our Center. [37, 38, 39 40, 41] 3) In case of Neurological Velo-Pharyngeal incompetence, often, the surgery only partially corrects the articulation disorders and the rhinolalia, but it allows better aerodynamic conditions for rehabilitation: Even a partial decrease of nasal air loss indirectly leads to: 1) Increase the intra-oral pressure 2) A better tone of dento-labial ([/f/v]) or dento-lingual ([/t/d/s/z]) articulation points and a better kinesthetic feed-back to work on them; 3) Increase the oral air reserve, allowing prolongations of syllable sequences and thus the slowdown of speech rate.

The Measure of Nasal Air Flow During Speech
Aerophonocope allows a semi-quantitative assessment of nasal air flow, expressed as a percentage at 80, 60, 50, 30, 20 and 100 per cent, compared to a maximal air flow objectified by nasal breath at the beginning of the examination, considered as the flow of 100 per cent for the speaker. This assessment is not sufficient for therapeutic decisions

The Opposition Between Voiced, and Unvoiced Consonants, for Healthy Individuals
Amelot describes for them that these voiced consonants are more resistant: they require less oral pressure and may lead to a slight nasal airflow.
But this notion, with aerophonoscopy is not verified in pathological individuals with hypoplastic or scarred soft palate: the voiced consonants, even if they require less oral pressure, are produced with a lesser resistance of the velopharyngeal sphincter, involving, in contrast, a greater nasal air flow An original fact from the experiment: we noticed that the major velar leakage may lead to compensatory movements of pharyngeal constriction, for oral vowels as for nasal ones, in particular the vowel /an/ and the syllable /man/ in French.

A Dysphonia
It may be a consequence of each type of velar disorder because of the excessive Nasal Loss. The voice is sometimes distorted to such an extent that the hypernasality is not heard, and gradually reveals itself during voice rehabilitation. Here, we can say that the feature of pathologic nasality influences the feature of voicing.

Conclusions
The assessment protocol via the aerophonoscope allows us to observe directly the permeability, and indirectly the tone and movements of the velopharyngeal sphincter. So it clearly leads to a great part of the etiological diagnosis of VPI, and thus can guide surgical decisions, and rehabilitation targets.

An Ultra-Sensitive and Objective Test
The aerophonoscope provides an ultra-sensitive means of nasal air flow detection and an assessment tool for the kinetics of the VPS, revealing the characteristics of its movements: its closing capacities, its speed, acceleration/deceleration, its steadiness, its sequence programming, more than the measurement of its opening.
The aerophonoscope confirms the variable and inhomogeneous character of nasal flow in the usual conditions of speech, especially with the striking phenomena of nasal coarticulation and of contaminations. These are absent or very moderate in normal but acute in pathological speech, whereas the perceptive assessments remain subjective. It allows an assessment revealing the dynamics of the closing/opening movements of the velopharyngeal sphincter according to the speed of speech, to the phonetic context, during the production of facilitating or non-facilitating oral phonemes, and to phonetic sequences.
Altogether, it provides a means of comparative assessment based on reproducible tests during child development from 4 to 20 years old and some elderly people.

Assessment of the True Severity of Velopharyngeal Incompetence
There is no linear correlation between the extent of nasal loss and the extent of the perceptive trouble (hypernasality and/or bad intelligibility) [42]. One of the explanations of that dissociation is given to us by the aerophonoscope.
The true severity of an open rhinolalia is not so dependent on the extent of pathological air flow, (correlated to the magnitude of the velopharyngeal gap) as it is on the slowness of the closing/opening of the velopharyngeal sphincter during the alternation of oral and nasal sounds. This slowness determines the contamination phenomenon of the nasality feature and thus an inaccurate phonological opposition between oral and nasal sounds.
Otherwise, the severity of the intelligibility depends also on several factors which are linked to etiology (hearing and nasal ventilation, dental and lips occlusion, swallowing disorders, lack of intra-buccal pressure, hypotonia, apraxia, dystonias, deafness, cognitive defect added.) and so, the treatment of this poly-pathological damage has to be multidisciplinary.
We notice that aerophonoscope provides a diagnosis means for the diagnostic of bucco-facial neurologic troubles.

A Rich Semiology
It helps us to determine three aerodynamic types (dysmorphic, neurological and dysfunctional disorders) by scanning French or English language specific phonemes and syllables and by practicing the tests of "sensitization". These 3 types may be associated (mixed types), in a lot of genetic syndromes.
Each type may contribute to choose the best surgical proceedings, such as to respect at the very most the VPS physiology: "To order from Nature, we have to obey Her".
These proceedings have to reduce the VP gap and give the best amplitude, a speed and steady muscular tone (surgery of filling, lengthening, toning by muscles transpositions).
This rich semiology opens up many research perspectives. The first of them is to experiment and complete the English protocol, which is described in appendix; then we have to explore the whole of phonemes, their phonotactic links with each nasal phonemes, to go on our researches about the correlation between aerodynamic and acoustic data.

A Pleasant and Efficient Means of Rehabilitation
Thanks to a visual feedback of a part of our phonation instrument: our nasal -and/or buccal production and our voicing or non-voicing production with a laryngeal microphone.