Intraoral Air Research Articles

Temporal Characteristics of Velopharyngeal Function in Children

This investigation was designed to examine the performance of children with normal speech on temporal aspects of aerodynamic tasks related to velopharyngeal closure.The investigation was a descriptive evaluation of variability in aerodynamic features related to velopharyngeal function during multiple repetitions of the word "hamper."Children without speech or velopharyngeal difficulties were seen in an experimental laboratory setting for the evaluation procedures.Twenty-seven subjects were recruited for the experiment. Three subjects were rejected because of behavioral difficulties, and the remaining 24 subjects were subdivided into 4 groups of 6 children (3 males and 3 females) aged 3, 6, 9, and 12 years. The children, who were from local schools and day care centers, volunteered to participate in the experiment. All of the children had age-appropriate speech, language, and hearing abilities, as determined by screening tests administered by one of the examiners (L.T.).Mean and variability of pressure-flow measures of peak intraoral air pressure and peak nasal airflow and the temporal measures accompanying each air pressure or airflow pulse were evaluated for the age groups of children examined in the experiment.The aerodynamic procedures employed to evaluate velopharyngeal closure during speech were reliable for use with young children. There was a numerical trend toward decreased duration of the temporal parameters with increasing age. Thus, children demonstrated durational values similar to those previously reported for normal-speaking adults. In general, peak oral air pressure and nasal airflow values were like those of previous investigations and demonstrated low variability across all age groups of children tested.The data from the present investigation provide a preliminary base for comparison of temporal features of velopharyngeal closure for the aerodynamic evaluation of children with impaired velopharyngeal function.

Effects of a pressure target on laryngeal airway resistance in children

The purpose of this study was to determine the effects of an intraoral air pressure target on estimation of laryngeal airway resistance (LAR) in normal children. Ten children produced the syllable /pi/ (a) with self-determined normal loudness, (b) with increased loudness, and (c) at a predetermined intraoral air pressure level of 6.5 to 7.5 cm of water. The target pressure level was selected because it was expected to result in estimated subglottal pressures that were lower than those associated with self-determined loudness levels. Results indicated significant differences in estimated subglottal pressure among the three conditions. As expected, estimated subglottal pressures were highest during loud speech and lowest during the pressure target task. LAR values associated with normal loudness were similar to values previously reported for children. The use of the pressure target resulted in LAR values that were reduced by 31% from normal loudness. These resistance values, however, were still greater than those reported for adult speakers at similar subglottal pressure levels. The results are explained relative to preferred loudness levels and vocal tract size differences in children and adults. It is suggested that use of a pressure target during estimation of LAR in children may provide additional data that more accurately reflect the aerodynamic integrity of the larynx. Implications for clinical assessment are discussed.

Characteristics of phonation offset and onset in normal adults and children

A major goal of research into the dynamics of vocal fold vibration is to specify the physical requirements for self-sustained oscillation, i.e., phonation. In recent years, theoretical and modeling studies have sought to define the necessary conditions for initiating phonation in laryngeal models of varying complexity, focusing especially on requisite pressure levels (the phonation threshold pressure), structural configurations (glottal width and the glottal convergence angle), and their interrelations. Conditions surrounding phonation offset have received somewhat less attention but are generally understood to involve different scale values of the same set of variables. This paper investigates voicing behavior around abduction for /h/ in normal English-speaking adults and 5-year-olds. Recordings consist of intraoral air pressure and oral airflow collected using a Rothenberg mask. DFT analyses of airflow signals from speakers whose /h/Us had voicing interruptions reveal that spectral changes accompanying phonation offset differ from those seen at phonation onset. Speakers show various individual patterns but the difference is typically most evident in the amplitude and bandwidth of the first harmonic. These results add to the empirical literature indicating that initiation and cessation of voicing do not occur under identical conditions. [Work supported by NIH.]

Direct measurement of subglottic pressure and laryngealresistance in normal subjects and in spasmodic dysphonia

This study tested the accuracy of indirect methods of measurement of laryngeal airway resistance in normal subjects and in spasmodic dysphonia (SD). The indirect method assumes that subglottic air pressure remains constant during the voiced segment of a syllable. In this study subglottic air pressure was directly measured via puncture of the cricothyroid membrane in seven normal subjects and seven subjects with SD. The true laryngeal airway resistance was calculated and compared with airway resistance measured using indirect techniques based on intraoral air pressure. In five of the seven normal subjects, subglottic air pressure did not remain constant during the voiced segment. As a result, the error produced using indirect method of calculating average laryngeal resistance for the normal subjects varied from -44% to +50%. For SD subjects the error ranged from -49% to +22%. In general, the indirect technique overestimated laryngeal airway resistance in normal subjects and underestimated the resistance in subjects with SD.

The future of dental amalgam: a review of the literature. Part 3: Mercury exposure from amalgam restorations in dental patients

This is the third article in a series of seven on the future of dental amalgam and covers mercury exposure from functioning dental amalgam restorations in patients. It firstly discusses the evidence for mercury release from amalgam fillings by considering the mechanisms of mercury release and its measurement in the expired air and the intra-oral air. In this connection it also discusses the various factors involved in the accurate measurement and calculation of mercury levels in these situations. It finally describes the various attempts to calculate the daily mercury dose from dental amalgam fillings and considers the likely accuracy of these calculations.

Voicing and aerodynamics of /h/ produced by women, men, and children

Patterns of consonantal voicing, especially as measured by voice onset time (VOT), have played an important role in discussions of speech timing control across populations. For example, relatively late acquisition of adultlike VOT values for voiceless aspirated stops in normal children has been attributed to the precise laryngeal-oral phasing required for these sounds. Implicit in such arguments is the assumption that the laryngeal and oral events themselves are comparable across subject groups. The present study attempts to assess the validity of this assumption in normal English-speaking women, men, and 5-year-old children. Recordings of oral airflow, intraoral air pressure, and acoustics were made as subjects produced a variety of voiceless consonants in prestress position within a carrier phrase. Analysis here focuses on /h/, which involves no oral obstruction and therefore affords the clearest picture of events at the glottis during the consonant. In these data, the patterns of flow increase, voicing offset and voicing onset during abduction for /h/ show certain differences across groups and suggest that some aspects of laryngeal behavior are not identical across these populations. Results are discussed in terms of group-related differences in anatomy and aerodynamic quantities.

Acoustic and aerodynamic studies of Korean vowel devoicing

Previous studies have shown that Korean high vowels are highly likely to be devoiced between fricatives and aspirated consonants based on acoustic and EMG data [Hirose (1974); Kim et al. (1993); Jun and Beckman (1993, 1994)]. In this paper, intraoral air pressure during vowel devoicing was examined together with acoustic data. Intraoral pressure was collected by inserting a sense tube Gaeltec S7b through the nostrils to the oropharynx, and the data were measured using the high-speed speech analysis system at RILP, Univ. of Tokyo. Three native Korean speakers repeated test words [siC] in a phrase at a normal and fast rate. The results show that there are four types of intraoral air pressure configurations: (1) completely devoiced vowel—a single peak rising during [s] and falling after C; (2) completely voiced vowel—a small peak during [s] and a fall during [i] and a bigger peak during C; (3) partially devoiced vowel, I—a single peak with a plateau or shoulder during [i]; (4) partially devoiced vowel, II—a high peak from [s] to C with a few quasiperiodic waves during [i]. More aerodynamic measurements based on EGG, airflow, and oral air pressure will be examined to understand the glottal gestures during the partially devoiced vowels.

Negative intraoral air pressures of deaf children with cochlear implants: physiology, phonology, and treatment.

The primary purpose of this investigation was to examine deaf children's use of negative intraoral air pressures (-Po's) from a physiological and a phonological perspective, with the hope of gathering insight into the strategies these children use to produce speech. A secondary purpose was to compare the effectiveness of two methods of treating these deviant productions. Subjects were four profoundly deaf children, age 6:6-9:2, who used cochlear implants and had demonstrated persistent use of -Po's. Po's were collected during production of CV syllables with initial [p] and [b] and a variety of vowel contexts. Two of the children used -PO's more often before low than high vowels. We suggest that this vowel-based pattern may result when deaf children learn to lower their larynges in response to visible jaw lowering cues. Another child presented with a pattern of more frequent -Po's before front than back vowels, suggesting that she may have expanded her pharynx anteriorly as she attempted to achieve an anterior tongue placement. Two children also clearly used -Po's more frequently for voiced than voiceless stops, possibly resulting from a tendency to use the degree rather than the timing of vocal fold adduction to distinguish voiceless and voiced phonemes. Two of the children were enrolled in a single-subject multiple baseline study to compare the effectiveness of traditional articulation treatment and visual-feedback treatment. The child who was a far less proficient talker demonstrated rapid and sustained change, whereas the better talker demonstrated minimal change with treatment. This study provides evidence that (a) deaf children use speech production strategies quite unlike those of normally hearing children and (b) deviant speech behaviors of deaf children should be treated before they become part of functional phonological systems. This work highlights the need to consider the unique speech behaviors of deaf children, and their reliance on alternate feedback mechanisms, when developing assessment and treatment procedures.

Determination of organometallics in intra-oral air by LT-GC/ICP-MS.

Low temperature gas chromatography (LT-GC) coupled on-line with inductively coupled plasma mass spectrometry (ICP-MS) has been used to identify volatile metal and metalloid compounds in human breath. After cryogenic sampling, the gas sample has been separated without any clean-up by increasing the temperature (-100 to +200 degrees C). Simultaneous determination of 11 elements with ICP-MS was used for screening analysis. The detection limits of volatile compounds in intra-oral air are in the range of ng m(-3). Dimethyl selenium has been determined in each gas sample from six test persons in the range of 0.08 to 0.98 microg m(-3).

Intraoral air pressure of alaryngeal speakers during a no-air insufflation maneuver

Intraoral air pressure was recorded during the production of the consonant cognate pairs /p/-/b/, /t/-/d/, and /s/-/z/ by eight esophageal speakers. These consonants were combined with the vowel /a/ to form CV, VCV, and VC syllables and produced under two experimental conditions: after the insufflation of air and without air insufflation. The purpose was to determine if the voiced-voiceless pressure difference associated with the production of cognate pairs would occur in the absence of an insufflated air flow source. The results revealed that peak intraoral air pressure magnitudes were significantly greater following the insufflation of air than without it. Moreover, the voiceless consonants were generally produced with greater peak air pressures than the voiced consonants under both experimental conditions, although not all contrasts were significantly different. Finally, peak air pressure magnitudes were significantly more variable in the air insufflation condition. The finding that the esophageal speakers exhibited a pressure difference relative to voicing in the absence of an insufflated air flow source provides support to the concept that intraoral air pressure may be an important variable in regulating and controlling consonant production.

Levator Veli Palatini Muscle Activity in Relation to Intraoral Air Pressure Variation in Cleft Palate Subjects

Levator Veli Palatini Muscle Activity in Relation to Intraoral Air Pressure Variation in Cleft Palate Subjects

Levator Veli Palatini Muscle Activity in Relation to Intraoral Air Pressure Variation in Cleft Palate Subjects

A comparison of the ranges of levator veli palatini EMG activity for speech versus a nonspeech task for subjects with cleft palate was the focus of this study. EMG values are also compared with subjects without cleft palate obtained in a previous study. Hooked-wire electrodes were inserted into the levator muscle of five adult subjects with cleft palate exhibiting mild hypernasality. Intraoral air pressure was measured concurrently. A blowing task was used to determine the subject's operating range for the levator muscle. Both the nonspeech and speech tasks were designed to sample the widest possible ranges of levator EMG activity. It was found that the subjects with cleft palate used a relatively high activation level for the levator muscle during speech, in relation to their total activation range, compared with the subjects without cleft palate. Implications are discussed in relation to possible anatomic and physiologic differences for cleft palate subjects compared to normal.

Combined estimation of mercury species released from amalgam.

Amalgam fillings constitute, after food, the main source of exposure to mercury for the general population. Banning amalgam would incur huge costs for additional dental treatment. An evaluation of potential health risks must be based on the mercury dose released from fillings. In this study, dose is estimated by a new procedure of mercury speciation which elutes the released elemental and inorganic mercury with solvents of differing polarity. We tested the procedure by incubating spherical amalgam pellets in a mixture of light paraffin oil and saline (0.9% NaCl). Release of mercury into paraffin and saline was linear in relation to both amalgam surface area and exposure time. Measurements with this method were then extended to a group of 21 amalgam-bearing volunteers. The absorbed dose averaged 4.8 micrograms/day compared with 3.7 measured conventionally in intra-oral air from the same persons. With both methods, the dose was significantly correlated to the number of amalgam-covered tooth surfaces. This dose, combined with the nearly equal mercury uptake from food, is far below the acceptable daily intake limit.

Levator Veli Palatini Muscle Activity in Relation to Intraoral Air Pressure Variation

The purpose of this investigation was to study the operating range of the levator veli palatini muscle for a nonspeech task (blowing) and to determine where in that range levator activity for speech lies. Ten adult subjects without speech or velopharyngeal abnormalities participated. Levator EMG activity for speech occurred in the lower region of the total range for blowing. In two subsequent experiments involving a subset of 4 subjects, it was found that overall effort may have had a small effect on levator activity apart from its role in velopharyngeal closure for aerodynamic purposes. The results of the main experiment are discussed in relation to the concept of threshold of fatigue as it may influence velopharyngeal control mechanisms.

Perceptual, acoustical and aerodynamic study of whispering

Perceptual study: Sixty-seven Japanese monosyllables were whispered by 12 normal speakers and tape-recorded. Listening tests by 24 normal listeners revealed that vowels, semivowels, nasals and fricatives were identified with excellent scores. Although voiced stop consonants were frequently judged as corresponding voiceless consonants, the difference in scores between the two groups was not statistically significant. Acoustical study: The acoustical features of the samples uttered by the subjects who were skilled in whispering showed that first-formant transition plays an important role in discrimination between voiced and voiceless stop consonants. Aerodynamic study: In the subjects who were skilled in whispering, intraoral air pressure was significantly higher in voiceless stop consonants than in corresponding voiced consonants. As a result, it was suggested that the articulation score of whispering would be improved when uttered under acoustical and/or aerodynamic monitoring.

Air pressure regulation during speech productiona)

Vocal tract pressures during speech tend to be maintained in the face of airway leaks that might be encountered by individuals with repaired palatal clefts. This study tested the hypothesis that such constant pressures can be explained as a consequence of constant pressure source characteristics of the respiratory system during speech production. This conceptualization differs from pressure regulation theories [e.g., D. Warren, Cleft Palate J. 23, 251-260 (1986)] which posit that active reflexive compensatory responses occur to regulate air pressure during speech. Four experiments were conducted to (a) confirm the distinction between constant flow versus constant pressure sources using a plastic vocal tract model, (b) compare air pressure and flow patterns associated with airway leaks in normal speakers to model data, (c) study the effects of gas density in the vocal tract model on air pressure and air flow patterns predicted by a nonreflexive constant pressure source hypothesis, and (d) compare air pressure and air flow patterns associated with airway leaks obtained from normal speakers using different gas densities to model data. Overall, observed flow and pressure patterns suggest the possible influence of constant pressure source characteristics of the respiratory system during speech on maintenance of intraoral air pressure.

Video-tape presentation of aerodynamic and respiratory kinematic measures during speech

A videotape of aerodynamic techniques for making measurements during speech production will be presented. Equipment shown will be: (1) a circumferentially vented pneumotachograph mask for sensing oral air flow [M. Rothenberg, J. Speech Hear. Res. 20, 155–176 (1977)], (2) a pitot tube for sensing intraoral air pressure, (3) a respirometer for air volume displacements, (4) a rotameter for calibrating airflow, and (5) a U-tube water manometer for calibrating air pressure. Discussion of calibration techniques and possible measurements during speech tasks will be displayed. A short segment of the tape will also demonstrate making simultaneous respiratory kinematic measures with linearized magnetometers using a child subject. Measures of lung volume, ribcage volume, and abdominal volume displacements will be shown. [Research supported by NIH.]

Airflow receptors in the lip and buccal mucosa

Airflow receptor afferents in the oral mucosa responding to changes in intraoral air pressure during blowing were found to be innervated by the infraorbital nerve. They provided one response corresponding to the onset of blowing, a second related to an increase in air pressure, a third corresponding to the cessation of blowing, and a fourth that exhibited little change throughout sustained blowing. Intraoral air pressure in the cavity between the lips and the velopharyngeal portal may be monitored by these receptors, and the data they provide may contribute to the control of phonation.

Esophageal speaker articulation of /s,z/: A dynamic palatometric assessment

Esophageal talker linguapalatal contact patterns and durations during /s/ and /z/ productions were examined using dynamic palometry instrumentation. It was found that sibilant groove narrowing is a physiologic compensation for a reduced air supply in esophageal speech. The place of esophageal /s, z/ articulation was on the anterior portion of the alveolar ridge as seen in normal speakers. Average medial groove width for esophageal /s/ was narrower than the 5–7-mm groove characteristics of normal speakers. Groove widths averaged 3 mm for /s/ and 4 mm for /z/. Systematic changes in groove widths across speech sounds, syllable position, and vowel context were also observed. Use of a narrower lingual groove was interpreted as a significant articulatory maneuver to meter out a limited intraoral air supply and effect more normal fricative durations.

Changes in laryngeal airway resistance in young adult men and women as a function of vocal sound pressure level and syllable context

<h2>Summary</h2> A noninvasive pressure-flow technique was used to assess laryngeal airway resistance (R_law) in eight young adult women and seven men. Syllable structures used were consonant-vowel (/pi/) and consonant-vowel-consonant (/bip/). The data were obtained from oscillographic records of intraoral air pressure and transglottal airflow over 2 consecutive days. Repetitions of each syllable context were produced at each subject's 25th, 50th, and 75th percentiles of vocal sound pressure level. No significant differences in R_law were found across days for the two groups. Women had significantly greater R_law than did men for the /pi/ and /bip/ contexts. Men showed a significantly greater average airflow rate than did women for both syllable contexts. Airflow, air pressure, and the ratio R_law increased as the sound pressure level of voice increased. The technique appears to be useful for characterizing certain features of laryngeal airway resistance for men and women.