Aerodynamic Measurements: Normative Data for Children Ages 6:0-10:11 Years
An Undergraduate Honors Thesis
Submitted to the
Faculty of Miami University
In the partial fulfillment of
The requirements for the degree of
Bachelor of Science
Department of Speech Pathology and Audiology
By
Beth Ann Salz
Miami University
Oxford, Ohio
2003
Advisor ___________________________
Barbara Weinrich, Ph. D.
Reader ____________________________
Joseph Stemple, Ph. D.
Reader ____________________________
Louise Van Vliet, Ph. D.
ABSTRACT
Normative measures of open quotient, speed quotient, maximum flow declination
rate (MFDR), and subglottal pressure were determined for 75 children between the ages
of 6 years 0 months to 10 years 11 months. The subjects produced a sustained “ah” at
comfort (acf), high (ahi), and low (alo) pitches for a minimum of five seconds. The
subjects also produced five repetitions of “pa” at comfort (pcf), high (phi), and low (plo)
pitches. For both “ah” and “pa” tasks, open quotient mean measures increased from low
frequency to comfort frequency and from comfort frequency to high frequency. Speed
quotient mean measures increased from low frequency to comfort frequency and
decreased from comfort frequency to high frequency. MFDR mean measures increased
from low frequency to comfort frequency and from comfort frequency to high frequency.
Subglottal pressure means increased from low frequency to comfort frequency and from
comfort frequency to high frequency. As age increased, open quotient, speed quotient,
and subglottal pressure mean measures decreased. MFDR mean measures increased as
age increased. The variables that reached significance for age, regardless of sex, were
open quotient at alo and acf, speed quotient at ahi, and MFDR at alo, ahi, and phi.
Key Words: Aerodynamic normative measures––Open quotient––Speed quotient––
Maximum flow declination rate––Subglottal pressure––Normal child voices
1
Aerodynamic Measurements: Normative Data for Children Ages 6:0-10:11 Years
INTRODUCTION
Phonotrauma, or vocal use/misuse/abuse, is one of the most commonly reported causes of
dysphonia.1, 2, 3 Typical prevalence rates of voice disorders in children range from 6% to 23%.4, 5
Vocal nodules are a diagnosed etiology of dysphonia frequently reported in children. In recent
prevalence studies, males with voice disorders between infancy and 14 years presented with
vocal nodules more often than other diagnoses.6 When assessing the parameters of voice, three
components can be evaluated: (a) aerodynamic qualities, (b) acoustic features, and (c) vocal fold
vibration characteristics (videostroboscopy). In order to evaluate the efficacy of treatment
procedures used with children who experience voice disorders, it is necessary to reference
normative data for the aerodynamic component of the voice assessment.
The aerodynamic component of the voice evaluation provides information related to the
valving efficiency of the glottis during phonation, as well as respiratory capacity. This yields
measurements for air pressure, airflow and air volume.7 Aerodynamic measures can be
determined using a Rothenberg circumferentially vented pneumotachograph face mask.8 This
non-invasive procedure allows the collection of oral airflow at the mouth. The wire mesh of the
face mask creates a resistive barrier to the airflow, creating a condition of higher pressure inside
the mask compared to outside. The resistance is constant, allowing the pressure variation to be
measured and the flow of air through the mask to be determined. Inverse filtering then removes
the effects of airflow modifications that have occurred as the signal passed through the oral
cavity. The resulting waveform is representative of the airflow pattern at the glottis, providing an
accurate representation of vocal fold movement during the vibratory cycle.2 In the present study
2
sustained vowels are used as stimuli in order to extract measures of airflow open quotient, speed
quotient, and maximum flow declination rate.
Airflow open quotient measures the length of time that the glottis is open in relation to the
duration of an entire vibratory cycle. Using a 20% criterion, open quotient is the time airflow
during the glottal cycle is greater than the AC component (AC = maximum flow minus minimum
flow).7 Measures of open quotient are useful in determining the efficiency or inefficiency of
vocal fold closure.7 Typical measures of open quotient for adult males, at a comfortable
frequency and intensity, range from 0.46 to 0.77. Females typically have higher open quotient
ratios, ranging from 0.56 to 0.95 at comfortable frequencies and intensities.9, 10 A decreased
ability of the vocal folds to close during the vibratory cycle is indicated by high open quotient
values that approach 1.0.11
Measures of speed quotient describe the duration of vocal fold abduction in relation to the
duration of adduction during a single vibratory cycle. A vibratory cycle with a speed quotient of
1.0 indicates the opening phase and closing phase are equal. Measures greater than 1.0 indicate
that the opening period is longer than the closing period. Measures less than 1.0 indicate that the
closing period is longer than the opening period.11 Typical speed quotient ratios for males, at a
comfortable frequency and intensity, range from 1.32 to 2.58. Females typically have lower
speed quotient measures, ranging from 1.16 to 2.33.9, 10
Maximum flow declination rate (MFDR) measures the maximum negative peak obtained
from the first derivative of the glottal waveform, or the rate of airflow cessation at glottal
closure, and is measured in liters/second/second.10 Typical measures of MFDR for adult males,
at a comfortable frequency, range from 255 to 309 liters/second/second. Typical measures for
the adult female at comfortable frequency are lower and range from 160 to 175
3
liters/second/second.9 A disorder in glottal closure and the resulting lower measures of MFDR
indicate an inability or resistance of the vocal folds to return to midline position. Abnormalities
can be perceptually identified by deficiencies in loudness and a breathy voice quality.7
Subglottal pressure is the amount of pressure exerted upon the vocal folds during adduction
and is measured in cmH2O. Direct measures of subglottal pressure are determined from the
subglottic structures through invasive procedures such as tracheal puncture. Indirect clinical
measures are derived from an estimation of the intraoral pressure during the production of a
voiceless plosive, such as /p/. In producing this phoneme, the vocal folds are abducted and the
lips are closed, sealing the oral cavity. The pressure within the oral cavity is then equal to the
subglottic pressure when the folds are adducted.2 Abnormalities in subglottal pressure measures
can be indications of impedance in the vocal tract, neuromuscular abnormalities of the chest
wall, and pulmonary disease.11
Aerodynamic evaluations of the adult population have indicated that variations in intensity
affect airflow and air pressure measurements. The primary determinants of vocal intensity are
subglottal pressure, fundamental frequency, and maximum flow declination rate.12 Intensity
changes affect the movement of the vocal folds by causing more gradual or abrupt opening and
closing of the folds, thereby altering the aerodynamic characteristics of the signal.10 As the
intensity of speech increases, maximum flow declination rate, speed quotient, and subglottal
pressure also increase.10, 13-15 In contrast, measures of open quotient decrease as intensity
increases.13-15 Comparisons between parameters of adult male and female voices indicate that
variations in the structure of the vocal tract also affect aerodynamic characteristics of speech.
The adult male voice exhibits a higher maximum flow declination rate and subglottal pressure
across all intensities, as well as a higher speed quotient in loud vocal intensities.10, 15, 16
4
The pediatric population has been found to differ from the measured aerodynamic
characteristics of the adult population. These differences are expected as a result of
developmental and structural differences between the pediatric and adult larynx.17 The vocal
system continuously changes as the control mechanisms of the central nervous system mature
and the vocal folds grow and develop. At birth, the vocal folds measure between 2.5 to 3.0 mm.
The mature female vocal fold measures between 11 to 15 mm, and the mature male vocal fold
measure between 17 to 21 mm. The mucosa of the vocal fold also thins, and the lamina propria
differentiates into a three-layer structure as the individual develops.2, 18 Other differences
between pediatric and adult laryngeal systems include smaller lung volume, a smaller larynx
with relatively thicker vocal folds in relation to length, and differences in musculature of the
laryngeal system.17 Subglottal pressure decreases significantly as age increases.16, 17 Estimates of
subglottal pressure for children aged 4 to7 years at comparable intensities are between 5.2 to
9.72 cm H2O and decrease with age. A child over 13 years of age is expected to have subglottal
pressure measurements between 3.9 to 8.04 cm H2O.17 While open quotient measurements of
children are similar to that of women, they are significantly larger when compared to that of
men.15 Maximum flow declination rate increases as age increases.14 Due to the similarity of prepubescent vocal tracts of boys and girls, aerodynamic measures of voice do not vary between
genders.15, 16
Adjustments of both physiologic structures and subglottal pressure are the primary cause of
changes in fundamental frequency.9 When producing a high-pitched vocalization, the cricothroid
muscle contracts, causing the vocal folds to become elongated. As a result of elongation, the
folds increase in tension and stiffness, and decrease in thickness and mass.1, 9, 12 Conversely, a
low-pitched vocalization is a result of relaxation of the cricothyroid muscle and contraction of
5
the vocalis muscle.1, 19 The vocal folds become shortened, more relaxed, and thicker.1, 20 When
positioned for low fundamental frequency vocalizations, the effects of subglottal pressure on the
vibratory pattern of the vocal folds become more significant.19 This effect occurs because vocal
fold tension has decreased, allowing more lateral stretching by the variation in subglottal
pressure.12
Holmberg, Hillman, and Perkell9 studied the effects of fundamental frequency on the
aerodynamic measures of maximum flow declination rate (MFDR), open quotient, speed
quotient, and subglottal pressure. In order to determine the relationship between these measures,
the subjects were directed to produce syllabic repetitions at normal, low, and high pitches at
“comfortable”, but unregulated intensity levels. As a result, intensity increased significantly
from normal to high-pitched vocalizations for both men and women. Significant differences
between normal and high-pitched conditions also occurred in MFDR and open quotient for men
and women. An increase in pressure for males and a decrease in open quotient for women were
the only significant differences between normal and low pitch vocalizations. The authors
concluded that fundamental frequency and intensity are interrelated. For example, signals of
greater intensity are typically higher in fundamental frequency.10 The increase in pressure causes
a corresponding increase in the stretch, or tension, of the vocal fold, thereby resulting in higher
pitch.12 Changes, such as increases in vocal fold tension and stiffness, affect both the
fundamental frequency and the intensity of the signal. However, regulation of intensity between
speech tasks can isolate the effects of changes in fundamental frequency.9
The purpose of this study was to provide descriptive data for the effects of fundamental
frequency on aerodynamic features of the normal pediatric voice.
6
METHODS
Subjects
Subjects included 77 children between the ages of 6 years 0 months to 10 years 11
months (Table 1). Two subjects were disqualified due to limitations in fundamental
frequency range and an inability to perform the required tasks. The subjects were
recruited from Oxford, Ohio and its surrounding areas. Intake questionnaires were
completed by each subject’s parent or guardian. Information collected included medical
history, current medications, extracurricular activities, and average daily intake of
specified liquids. The height and weight of each subject (Table 2), as well as concerns
regarding articulation, language, hearing, and voice skills, were recorded by the
researchers. Inclusion criteria for subjects were (a) absence of respiratory illness, (b)
normal hearing ability, and (c) normal voice characteristics.
Equipment
The aerodynamic data were obtained from instrumentation that consisted of a
medium, adult circumferentially vented pneumotachometer face-mask coupled to a
narrow-band pressure transducer (PTL-1) and a separate wide-band pressure transducer
(PTW-1) (Glottal Enterprises model MS 100 A-2). A JVC videocassette recorder was
used to record airflow and pressure signals onto a VHS videotape. The instrumentation
was calibrated for pressure at 5, 10, and 15 cm H20 and for a flow rate of .5 liters per
second and a volume of 2 liters exchange. Data collection was conducted at the Miami
University Speech and Hearing Clinic Voice Laboratory, Oxford, OH.
7
Speech Tasks
The subjects produced a sustained “ah” at comfort (acf), high (ahi), and low (alo)
pitches for a minimum of five seconds. The subjects also produced five repetitions of
“pa” at comfort (pcf), high (phi), and low (plo) pitches. The series of five repetitions was
produced without interruption for breathing. Each “pa” was approximately 1.5 seconds
in length as prompted by the researcher. The subjects performed three satisfactory trials
for each condition. The order of the tasks was randomized for each subject.
Outcome Variables
The following variables were measured for each trial: open quotient, speed
quotient, maximum flow declination rate (MFDR), subglottal pressure, fundamental
frequency, and intensity defined as root mean square (RMS).
Procedures
Comfort, low, and high pitches were established for each subject and recorded on a
data sheet. The comfort pitch was determined by asking the subjects to sustain “ah” at a
“comfortable level.” High and low pitches were then established by using an electronic
keyboard (Optimus Concertmate – 690) and modeling to produce the “ah” at the desired
pitches according to the subject’s range. Pitch and intensity were monitored by using an
electronic tuner (Seiko Chromatic Tuner ST-909) and a sound level meter (Radio Shack
Digital Sound Level Meter). After training and rehearsal, the pneumotachometer facemask was placed on the child’s face and the child was instructed to breathe easily through
the mask. The subject was then instructed to listen to the note as demonstrated by the
8
keyboard and modeled by the researcher, take a deep breath, and begin task production.
The mask was removed when a minimum of three satisfactory trials were completed for
the task. The next task was explained and rehearsed, and the process was repeated.
The entire aerodynamic data collection process required between 8 to 30 minutes for
each subject. At the completion of the data collection process for each subject, the
minimum flow offset values were evaluated for mask leaks. As established by Ramig
and Dromey21, a minimum flow offset less than -.05 L/s indicated a mask leak and
necessitated replication of the task. Two of the three trials for each task were chosen for
analysis with respect to matching data sites for frequency and intensity. Approximately
100 millisecond segments of each trial were isolated from the middle of each vowel
segment, or middle “pa” syllable, and analyzed.
RESULTS
Fundamental Frequency and Intensity
Mean fundamental frequency measures ranged from 234.18 Hz (plo) to 339.09 Hz
(phi) (Figure 1). Mean fundamental frequencies were higher for females than for males
in all tasks (Figure 2). Measures of intensity (RMS) decreased from low frequency to
comfort frequency tasks and increased from comfort frequency to high frequency tasks.
All mean intensity measures for “pa” tasks were greater than means for “ah” tasks at the
equivalent frequencies (Figure 3). Mean intensity measures were greater for males in all
tasks (Figure 4).
9
Open Quotient
Differences in open quotient mean measures for all speech tasks were small
(Figure 5). Measures for all subjects ranged from 0.68 (alo) to 0.73 (phi). Open quotient
mean measures increased for both “ah” and “pa” tasks from low frequency to comfort
frequency and from comfort frequency to high frequency. Measures showed no pattern
of variation by age (Tables 3-8). As noted in Table 9, significant differences according to
age were found only in the tasks of alo (F(1,72) = 5.39, p = 0.02) and acf (F(1,72) = 7.76,
p = 0.01). No significant differences occurred in relation to gender (Table 9). However,
open quotient mean measures were lower for females in all tasks except phi, in which
male and female measures were equal (Figure 6).
Speed quotient
Speed quotient mean measures for all subjects ranged from 2.09 (ahi) to 2.67
(pcf) (Figure 5). For both “ah” and “pa” tasks, mean measures increased from low
frequency to comfort frequency and decreased from comfort frequency to high frequency.
The highest mean measures for speed quotient were observed in the comfort frequency
condition, while the lowest mean measures were observed in the high frequency
condition. No patterns were observed for speed quotient in relation to an increase in age
(Tables 3-8). As noted in Table 9, a significant difference for speed quotient in relation
to age was found only in ahi (F(1,72) = 4.40, p = 0.04). Differences in mean measures
between males and females were small. However, mean measures were lower for
females in all “ah” tasks and in phi (Figure 7).
10
Maximum Flow Declination Rate
Mean maximum flow declination rate (MFDR) measures ranged from 107.13
L/s/s (alo) to 174.41 L/s/s (phi) (Figure 8). For both “ah” and “pa” tasks, mean measures
increased from low frequency to comfort frequency and from comfort frequency to high
frequency. Mean “pa” tasks were greater than mean “ah” tasks at equivalent frequencies.
As noted in Table 9, significant differences were found for gender in the tasks of ahi
(F(1,72) = 4.61, p = 0.04) and phi (F(1,72) = 6.51, p = 0.01) and for age in the tasks of
alo (F(1,72) = 7.05), p = 0.01), ahi (F(1,72) = 4.69, p = 0.03), and phi (F(1,72) = 4.93, p
= 0.03). Females had lower mean MFDR measures than males in all tasks (Figure 9).
Measures of MFDR increased as a function of age (Tables 3-8).
Subglottal Pressure
Mean measures of subglottal pressure ranged from 8.72 cmH2O (plo) to 9.87
cmH2O (phi) (Figure 10). Subglottal pressure means increased from low frequency to
comfort frequency and from comfort frequency to high frequency. Females had lower
subglottal pressure means than males in all tasks (Figure 11). As noted in Table 9, a
significant difference was found for gender in the task of plo (F(1,72) = 3.83, p = 0.05).
No significant differences were found in relation to age (Table 9), however mean
measures tended to decrease as age increased (Tables 3-8).
DISCUSSION
The purpose of the present investigation was to increase the database of
aerodynamic measures of children with normal voices. For the total group of subjects
11
(N=75), measures of open quotient were comparable to values reported for adult females,
while speed quotient measures were higher than adult males and females.
9, 10, 15
The mean
maximum flow declination rates were lower for children than adults, but were
9
comparable to rates previously reported for adult females. Subglottal pressure mean
9, 10
values were higher than normal values reported for the adult population.
Fundamental frequency (Figure 1) and open quotient (Figure 5) means were
similar for “ah” versus “pa” tasks at equivalent frequency task levels (alo/plo; acf/pcf;
ahi/phi). However, mean measures of intensity, speed quotient, and maximum flow
declination rate were higher for all “pa” tasks, indicating that the /p/ had several effects
on vowel production. The subjects vocalized with greater intensity (Figure 3), thus
causing a longer opening phase of the vocal folds (Figure 5) and a faster rate of airflow
cessation at vocal fold closure (Figure 8).
Several aerodynamic variable trends were observed among the tasks as frequency
increased. Speed quotient means decreased for high-pitched tasks (Figure 5), suggesting
that the shorter opening phase of the vocal folds is most affected by high frequency
conditions. Maximum flow declination rate (Figure 8) increased steadily as pitch
increased, indicating that increased fundamental frequency causes the folds to close at a
faster rate. Subglottal pressure means (Figure 10) also increased as pitch increased, which
indicates that increased pressure below the vocal folds is necessary to start and maintain
the vibratory cycle as fundamental frequency increases.
As predicted from previous studies,
15, 16
differences between male and female
children for the majority of aerodynamic measurements were not significant. Those
variables that reached significance (p< or = 0.05) were maximum flow declination rate
12
(MFDR) at ahi and phi, and pressure at plo (Table 9). For all three tasks, males had
significantly higher mean values than females (Figures 9 & 11). The following trends
were observed in the mean data. Open quotient mean measures were lower for females in
all tasks except phi, in which male and female measures were equal (Figure 6). Mean
measures for speed quotient were lower for females in all “ah” tasks and the phi task
(Figure 7). Females had lower mean values for maximum flow declination rate (Figure 9)
and subglottal pressure (Figure 11) in all tasks. Fundamental frequency means were
higher for females than males (Figure 2).
In contrast to adult measures, 9, 10 female children had lower open quotient means
than male children (Figure 6). However, mean open quotient measures for both male and
female children were higher than those of adult males and comparable to that of adult
females.9, 10 The decrease of open quotient means as age increases (Tables 3-8) indicated
an increased efficiency of vocal fold closure as the individual reaches maturity. As with
adult measures, 9, 10 speed quotient mean measures of male and female children were
comparable. Mean speed quotient means of children (Figure 5) were typically higher
than those of adults, 9, 10 indicating that the length of the opening phase of the vocal folds
decreases with age. As in the adult population, 9 maximum flow declination rate means
were greater for male children than for female children (Figure 9). Mean MFDR
measures for children (Figure 8) were lower than the adult male and comparable to the
adult female,9 indicating that male children have an increased ability for the vocal folds
to completely return to midline as they mature.
There were significant aerodynamic measurement age effects, regardless of sex,
for six tasks. Those variables that reached significance (p< or = 0.05) were open quotient
13
(OQ) at alo and acf, speed quotient (SQ) at ahi, and MFDR at alo, ahi, and phi (Table 9).
There were negative effects for OQ and SQ (as age increased, OQ and SQ decreased),
and positive effects for MFDR (as age increased, MFDR increased). As reported by
16
17
Netsell et al. and Keilmann and Bader, mean pressure values decreased as age
increased (Tables 6-8).
The aerodynamic measurement differences found between adults and children,
who were analyzed in this study, support the data in the literature. It is apparent that
children with voice disorders should be compared to other children with normal voices of
the same age and sex, rather than the adult database.
14
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Management. San Diego: Singular Publishing Group; 2000.
2. Andrews, ML, Summers, AC. Voice Treatment for Children and Adolescents.
San Diego: Singular; 2000.
3. Deem, JF, Miller, L. Manual of Voice Therapy. Austin: Pro-Ed; 2000.
4. Senturia B, Wilson F. Otorhinolaryngologic findings in children with voice
deviations: Preliminary report. Ann Otol Rhinol Laryngol. 1968;77:1027-1042.
5. Silverman E, Zimmer C. Incidence of chronic hoarseness among school-age
children. J Speech Hear Disord. 1975;40:211-215.
6. Herrington-Hall B, Lee L, Stemple J, Niemi K, McHone M. Description of
laryngeal pathologies by age, gender, and occupation in a treatment seeking sample. J
Speech Hear Disord. 1988;53:57-65.
7. Sapienza, CM. Glottal airflow: Instrumentation and interpretation. The Florida
Journal of Communication Disorders, 1996;16:3-7.
8. Rothenberg, M. A new inverse filtering technique for deriving the glottal
airflow waveform during voicing. J Acous. Soc. Am. 1973;53:1632-1645.
9. Holmberg EB, Hillman RE, Perkell JS. Glottal airflow and transglottal air
pressure measurements for male and female speakers in low, normal, and high pitch. J
Voice. 1989;3:294-305.
15
10. Holmberg EB, Hillman RE, Perkell JS. Glottal airflow and transglottal air
pressure measurements for male and female speakers in soft, normal, and loud voice. J
Acoust. Soc. Am. 1988;84:511-529.
11. Baken, RJ, Orlikoff, RF. Clinical Measures of Speech and Voice. San Diego:
Singular Publishing Group; 2000.
12. Scherer, RC. Physiology of phonation: A review of basic mechanics. In C.
Ford & D. Bless (Eds.), Phonosurgery: Assessment and Surgical Management of Voice
Disorders (pp. 77-93). New York: Raven Press, Ltd; 1991.
13. Dromey C, Stathopoulos ET, Sapienza CM. Glottal airflow and
electroglottographic measures of vocal function at multiple intensities. J Voice.
1992;6:44-54.
14. Sapienza CM, Stathopoulos ET. Respiratory and laryngeal measures of
children and women with bilateral vocal fold nodules. J Speech Hear Res. 1994;37:12291243.
15. Stathopoulos ET, Sapienza CM. Respiratory and laryngeal measures of
children during vocal intensity variation. J Acoust. Soc. Am. 1993;94:2531-2543.
16. Netsell R, Lotz WK, Peters JE, Schulte L. Developmental patterns of laryngeal and
respiratory function for speech production. J Voice. 1994;8:123-131.
17. Keilmann A, Bader C. Development of aerodynamic aspects in children’s
voice. International Journal of Pediatric Otorhinolaryngology. 1995;31:183-190.
18. Hirano, M, Kurita, S, Nakashima, T. Growth, development, and aging of human
vocal folds. In D. Bless & J. Abbs (Eds.), Vocal Fold Physiology: Contemporary Research &
Clinical Issues (pp. 22-43). San Diego: College-Hill Press; 1983.
16
19. Atkinson, JE. Correlation analysis of the physiological factors controlling
fundamental voice frequency, J Acoust Soc Am 1978;48:249-55.
20. Stevens KN. Physics of laryngeal behavior and larynx modes. Phonetica
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17
Table 1. Age Distribution of Subjects
6.0-6.11
7.0-7.11
8.0-8.11
9.0-9.11
10.0-10.11
Total
Male
2
13
6
7
10
38
Female
3
3
12
12
7
37
Total
5
16
18
19
17
75
18
Table 2. Height and Weight Ranges and Means
6.0-6.11
7.0-7.11
8.0-8.11
9.0-9.11
10.0-10.11
Height Range
(inches)
48.5-50
48-52
48-61.75
49-57.5
54-62
Mean Height
(inches)
48.55
49.81
51.31
54.14
55.46
Weight
Range (lbs.)
47-64
49-71
46-85
52-111
58-132
Mean Weight
(lbs.)
56.1
58.28
71.44
79.47
81.67
19
Figure 1. Fundamental Frequency Means
350
300
250
Hz
200
150
100
50
0
alo
acf
ahi
20
plo
pcf
phi
Figure 2. Fundamental Frequency Means by Sex
350
300
250
Hz
200
Male
Female
150
100
50
0
alo
acf
ahi
plo
21
pcf
phi
Figure 3. Mean RMS
0.49
0.48
0.47
0.46
0.45
0.44
0.43
0.42
0.41
0.4
alo
acf
ahi
plo
22
pcf
phi
Figure 4. RMS Means by Sex
0.6
0.5
0.4
Male
Female
0.3
0.2
0.1
0
alo
acf
ahi
plo
23
pcf
phi
Figure 5. Open Quotient and Speed Quotient
Means
3
2.5
2
% 1.5
1
0.5
0
alo
acf
ahi
Mean Open Quotient
24
plo
pcf
Mean Speed Quotient
phi
Table 3. Mean Values at Alo by Age
Age
6 yrs
7 yrs
8 yrs
9 yrs
10 yrs
MFDR (L/s/s)
87.80
92.88
104.46
111.60
122.32
OQ (%)
0.69
0.74
0.67
0.71
0.61
SQ (%)
2.67
2.50
2.28
2.63
2.12
Fo (Hz)
224.14
232.35
251.38
233.78
221.70
25
Table 4. Mean Values at Acf by Age
Age
6 yrs
7 yrs
8 yrs
9 yrs
10 yrs
MFDR (L/s/s)
107.06
136.57
146.87
138.65
144.47
OQ (%)
0.71
0.75
0.73
0.69
0.63
SQ (%)
2.49
2.57
2.47
2.64
2.19
Fo (Hz)
248.27
271.55
294.42
278.43
266.86
26
Table 5. Mean Values at Ahi by Age
Age
6 yrs
7 yrs
8 yrs
9 yrs
10 yrs
MFDR (L/s/s)
124.93
149.59
145.83
153.66
186.51
OQ (%)
0.69
0.75
0.72
0.72
0.69
SQ (%)
2.72
2.20
2.07
2.05
1.90
Fo (Hz)
302.28
333.23
351.33
346.84
333.77
27
Table 6. Mean Values at Plo by Age
Age
6 yrs
7 yrs
8 yrs
9 yrs
10 yrs
MFDR (L/s/s)
72.63
120.29
130.10
119.43
135.88
OQ (%)
0.69
0.73
0.66
0.75
0.63
SQ (%)
2.28
2.50
2.36
3.03
2.28
Fo (Hz)
224.01
234.16
253.51
235.29
222.15
Pressure
(cmH2O)
9.62
9.48
8.73
8.21
8.36
28
Table 7. Mean Values at Pcf by Age
Age
6 yrs
7 yrs
8 yrs
9 yrs
10 yrs
MFDR (L/s/s)
112.96
147.27
150.02
157.95
155.67
OQ (%)
0.67
0.79
0.70
0.72
0.65
SQ (%)
2.51
2.78
2.54
2.95
2.44
Fo (Hz)
244.97
270.49
300.01
278.22
264.09
Pressure
(cmH2O)
10.05
9.47
9.72
9.08
8.70
29
Table 8. Mean Values at Phi by Age
Age
6 yrs
7 yrs
8 yrs
9 yrs
10 yrs
MFDR (L/s/s)
132.51
171.70
163.25
175.77
198.04
OQ (%)
0.73
0.76
0.74
0.74
0.70
SQ (%)
1.58
2.30
2.29
2.16
2.09
Fo (Hz)
293.17
326.25
348.11
345.21
332.80
Pressure
(cmH2O)
10.83
10.77
9.86
9.67
9.08
30
Table 9. Analysis of Covariance
Dependent Variables
Statistical Values
alo
sex
age
acf
sex
age
ahi
sex
age
plo
sex
age
pcf
sex
age
phi
sex
age
*p < or = 0.05
F
OQ
p
F
SQ
p
MFDR
F
p
Pressure
F
p
0.08
5.39
.78
.02*
0.19
1.88
.67
.17
1.73
7.05
.19
.01*
NA
NA
NA
NA
1.81
7.76
.18
.01*
0.77
0.82
.38
.37
3.50
1.21
.07
.27
NA
NA
NA
NA
0.12
1.44
.73
.23
0.87
4.40
.35
.04*
4.61
4.69
.04*
.03*
NA
NA
NA
NA
0.22
1.66
.64
.20
0.06
0.17
.81
.68
1.55
3.16
.22
.08
3.83
1.62
.05*
.21
0.25
3.77
.62
.06
0.39
0.13
.53
.71
1.07
1.80
.30
.18
1.24
0.99
.27
.32
0.02
2.11
.90
.15
0.60
2.54
.44
.12
6.51
4.93
.01*
.03*
2.83
2.35
.10
.13
31
Figure 6. Open Quotient Means by Sex
0.73
0.72
0.71
0.7
Male
Female
% 0.69
0.68
0.67
0.66
0.65
alo
acf
ahi
plo
32
pcf
phi
Figure 7. Speed Quotient Means by Sex
3
2.5
2
Male
Female
% 1.5
1
0.5
0
alo
acf
ahi
plo
33
pcf
phi
Figure 8. MFDR Means
180
160
140
120
Liters/second/ 100
second
80
60
40
20
0
alo
acf
ahi
34
plo
pcf
phi
Figure 9. MFDR Means by Sex
200
180
160
140
120
Liters/second/
100
second
80
60
40
20
0
Male
Female
alo
acf
ahi
35
plo
pcf
phi
Figure 10. Subglottal Pressure Means
10
9.8
9.6
9.4
9.2
cmH2O
9
8.8
8.6
8.4
8.2
8
plo
pcf
36
phi
Figure 11. Subglottal Pressure by Sex
12
10
8
cmH2O
Male
Female
6
4
2
0
plo
pcf
37
phi