Folia phoniat. 27: 401 409 (1975)
Air Flow Onset and Variability Thomas Murry and Linda K. Schmitke' Veterans Administration Hospital San Diego. Calif.
Previous investigations o f mean air flow rate in normal voices have demon strated its usefulness in determining glottal resistance (van den Berg, 1956; Isshiki, 1964). expiratory force ( Yanagihara et al., 1966), and vocal initiation characteristics (Koike et a i, 1967). In addition, aerodynamic relationships which pertain to laryngeal dysfunction (Yanagihara and von Leden, 1967; Hirano et al., 1968) have been found to be useful for diagnosing laryngeal pathology. The results o f these studies have shown that, in general, mean air flow rate in normal subjects has little relationship to mean fundamental frequency and has a moder ate relationship to vocal intensity, especially at the upper end of the phonational range, in patients with voice disorders, mean air flow rate has been generally related to the degree of glottal approximation, changes in vocal fold mobility and mass changes on the vocal folds. Mean air flow rates in pathological voices have been obtained ranging from 20 to 1,000 cm3/sec (Yanagihara and von Leden, 1967) while the normal mean air flow rates are approximately 110 cm3/ sec. In addition to knowing the mean air flow rate, information about the within sample and sample-to-sample variability in the flow rate would also appear to be diagnostically significant. If the instantaneous fluctuations in air flow rate were excessively large in persons with voice disorders, then mean air flow rate alone would appear to have limited diagnostic usefulness. Some fluctuation, however, in mean air flow rate can be expected and. in fact, may be related to the physiology of the laryngeal dysfunction. For example, if the air flow showed 1 The authors wish to acknowledge the support o f the Veterans Administration Hospi tal. San Diego, Calif. Mrs. Schmitke is now at the San Diego Speech, Hearing and Neurosensory Center.
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Received: August 18, 1975; accepted: September 10, 1975.
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significant variation within any one sample, and an overall high mean air flow rate with a large sample-to-sample difference, it may be hypothesized that the adequacy of glottic closure varies and, consequently, affects the mean air flow rate. There is little information on the sample-to-sample changes in the mean air flow rates o f normal talkers and persons with laryngeal dysfunctions. The pur pose of this study was to examine the variability o f mean air flow rate and the onset pattern of air flow in normal voices and in a variety o f dysphonias when the phonatory samples are produced under controlled conditions.
Method Subjects 9 subjects with normal voices and 25 subjects with various voice disorders participated in the study. Confirmation o f the diagnoses in the 25 subjects with voice disorders was based on the patient’s medical record and upon indirect laryngoscopy by an otolaryngolo gist. The normal subjects ranged in age from 19 to 37 years; the subjects with voice dis orders ranged from 32 to 77 years in age. Equipment Figure 1 is a block diagram o f the apparatus used to record the air flow and voice signals. Air flow rate was recorded through a face mask (Bennett. Benefit) connected to a pneumotachograph (Wiedeman, No. 20). The flow' rate was transduced into an equivalent voltage with a differential pressure transducer (Statham PM 97), amplified and recorded on a visicorder (Honeywell 1508C). The air flow channel was calibrated by passing a constant air supply through a rotameter and the pneumotachograph and recording the calibration trace on the visicorder. A linear calibration between 50 and 1200 cm3/sec was obtained.
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Fig. I. Block diagram of the apparatus used to record the air flow and voice signals and to monitor the sound level of the talker.
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The voice signal was sensed with a dynamic microphone (Electrovoice 664) located approxi mately 8 in. in front of the pneumotachograph. The voice signal was recorded on a magnetic tape recorder (Revox A-77) and a second channel o f the visicorder. A second microphone (Bruel & Kjaer 4131) was located 12 in. in front o f the pneumotachograph and connected to a sound-level meter (Bruel & Kjaer 2209). The patient used the sound-level meter to monitor the intensity o f his vocalizations. Procedure For this study, all subjects produced at least three phonatory samples of the sustained vowel la/ at their most comfortable level of voval production. To obtain these samples, each patient was seated comfortably with his face in the mask which was attached to the pneu motachograph. He was instructed to produce samples of the vowel /a/ at a comfortable level. The patient practiced until he could produce 4 or 5 consecutive 4-sec samples within 2 dB on the sound-level meter (C scale). The mean o f the samples to the nearest decibel was accepted as the target for the patient to reach during the test conditions. The patient then produced 3 -5 samples o f the vowel la/ at the target level while monitoring the sound-level meter. Initial overshoot of sound-level meter due to sudden onset o f phonation was not considered in selecting the final 3 samples for evaluation. Care was taken that no samples with obvious deviations in perceived pitch or quality were recorded. The tape-recorded signals were then processed through a graphic level recorder (Bruel & Kjaer 2305) to verify that the intensity, with the exception o f the first second o f each sample, did not vary by more than 2 dB. The first 4 sec o f three samples of /a/ for each subject were measured at 100-msec intervals. Thus, 40 points in time were measured for each phonatory sample. The means and standard deviations o f the air flow rates for the 1st sec and for the 2nd, 3rd and 4th sec combined were obtained.
Results The results o f this study are divided into two parts. The first part presents the results o f the 2nd, 3rd, and 4th seconds o f the phonatory samples (steadystate portion). The initial second (onset of phonation) is covered separately. The mean and standard deviation2 o f the air flow rates for the 2nd, 3rd, and 4th seconds of the 3 phonatory samples o f /a/ are shown in table I. These values were obtained from sampling the air flow tracing at '/io-sec intervals; thus, a total o f 30 values were obtained for each 3-sec sample. The final two columns show the overall mean and standard deviation for the combined 9 (3 samples X 3 sec) sec o f phonation. The normal subjects ranged from 57 to 183 cm3/sec in mean air flow rate, while those with voice disorders had a range from 139 to 819 cm3/sec. For any one normal subject there was as much as 55.5 cm3/sec
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! A Poisson variate transformation was applied to the data in order to accurately compare the standard deviations o f all subjects. This transformation may be used when the variances tend to be a function of the means. The transformation has the form SD = V sD (Winer, 1962). All standard deviations reported in this paper arc given in the Poisson transformation.
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Tablet. Mean and standard deviations o f the 2nd, 3rd and 4th seconds o f 3 samples o f the vowel /a/ and the overall mean and standard deviation (cm3/sec) o f the 3 samples Subject
X 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
Sample 2
Sample 1
57.50 66.50 157.50 96.00 138.00 120.00 143.00 150.50 144.00 231.52 201.00 139.50 159.50 240.00 210.00 812.00 295.00 343.00 611.50 298.00 291.50 145.00 245.00 165.00 218.50 218.00 293.00 217.00 191.50 307.00 220.00 256.00 162.00 288.50
SD 2.92 2.55 3.16 2.12 3.61 2.92 2.65 2.65 2.35 4.80 4.12 4.47 3.54 4.58 4.12 5.96 5.50 4.69 4.00 5.10 4.47 2.65 3.61 4.00 5.00 10.10 3.94 4.24 3.67 4.18 3.67 3.81 3.46 2.24
Overall
Sample 3
X
SD
X
SD
X
SD
88.00 95.00 170.00 87.50 152.50 120.00 122.00 144.50 145.00 265.50 267.00 207.50 160.50 206.50 243.00 853.50 289.50 405.00 540.00 337.00 264.00 141.00 254.00 167.00 184.50 309.00 277.00 163.00 237.00 303.00 223.50 260.50 158.50 449.00
2.00 1.87 4.08 1.73 3.46 2.65 2.45 3.16 2.35 5.10 5.92 3.87 3.61 3.94 4.95 6.00 6.82 5.36 5.20 3.67 3.39 3.54 3.67 2.83 4.06 8.37 3.74 6.32 3.87 4.36 3.72 4.53 4.74 4.12
96.00 97.00 183.50 77.00 134.50 144.50 97.50 154.00 143.00 250.00 255.00 217.00 155.00 229.50 207.50 891.00 279.00 365.00 606.50 350.00 270.00 144.00 237.50 170.00 165.00 315.00 297.00 247.50 234.00 295.00 217.50 268.50 142.50 432.50
1.87 2.00 4.02 3.00 2.92 2.12 2.12 3.39 3.08 4.58 5.52 3.87 3.00 4.18 4.08 5.10 5.87 4.53 6.52 2.65 4.06 2.65 2.74 3.32 3.46 8.63 3.54 5.48 3.87 4.47 3.81 4.42 3.16 5.24
80.50 86.17 170.33 86.83 141.67 128.17 120.83 149.67 144.00 249.00 241.00 188.00 158.33 225.33 220.17 852.17 287.83 371.00 586.00 328.50 275.15 143.33 245.50 167.33 189.33 280.67 289.00 209.17 220.83 301.67 220.33 261.67 154.33 390.00
4.50 4.13 3.61 3.09 3.09 3.76 4.77 2.18 1.00 4.13 5.93 6.50 1.71 4.14 3.38 6.29 2.85 5.61 6.32 5.21 3.80 1.44 2.87 1.59 5.20 7.37 3.25 6.54 5.04 2.47 1.73 2.52 3.22 9.40
difference from sample-to-sample and 161 cm3/sec for those subjects with voice disorders. Within any one sample, however, the normal subjects were highly stable, as evidenced by the within-sample standard deviations, as compared to the majority of the subjects with disorders.
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Means and standard deviations expressed in cubic centimeters per second and transformed according to Poisson variate transformation.
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Table II. Mean and standard deviation o f the 2nd, 3rd and 4th seconds o f each sub ject’s 3 samples o f the vowel grouped according to diagnostic category Group
n
X
SD
Range
Normals Post-radiation Laryngeal cancer Unilateral paralysis Polypoid degeneration Intubation dysphonia Vocal nodules Functional vocal abuse Hemilaryngectomy
9 5 1 5 3 5 1 3 2
123.13 212.33 220.17 485.10 221.33 227.10 220.83 261.22 272.17
5.67 6.15 4.43 15.32 8.34 7.40 5.15 6.40 12.89
57.50 183.50 139.50 255.00 210.00-243.00 279.00 891.00 141.00-291.50 163.00-315.00 191.50-237.00 217.00 307.00 142.50-449.00
The final two columns in the table show the mean and standard deviation o f the combined samples for each subject. Again the means for the normals are lower than those for the other subjects. Table II presents the mean air flow rate data grouped according to diagnosis. From table 11, it can be seen that the normal group has the lowest mean air flow rate and the unilateral vocal cord paralysis group has the highest mean air flow rate. The other groups, including the laryngeal cancer and vocal nodule patients (in which there is only 1 patient o f each type), show very similar mean air flow rates. Indeed, the ranges for these groups, with the exception o f functional vocal abuse groups, are also very similar. While the number for each group is small, there does not appear to be sufficient separation o f mean flow rate values to categorize the diagnosis on the basis o f mean air flow rate alone. Only the normals and the unilateral paralysis patients might be distinguished sufficiently on the basis o f flow rate alone. With regard to the variability found in the samples, the standard deviations indicate that those individuals with functional vocal abuse have the smallest sample-to-sample variation, even smaller than the normals. Thus, while their mean air flow rate was similar to the other groups, their standard deviation was smaller than all other groups. In addition to examining the steady-state portion o f the vowel samples, the initial 1 sec was evaluated in terms o f the onset of the air flow. After one o f the experimenters drew contours o f best fit for all flow samples, 6 composite groupings were derived. All but 1 o f the 102 samples produced by the subjects were assigned to 1 of the 6 categories. Figure 2 shows the 6 general categories o f mean air flow rate onset. Type 1 has a rise time within 0.15 sec, a peak and
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Means, standard deviations and ranges expressed in cubic centimeters per second and transformed according to Poisson variate transformation.
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stabilizes within 0.5 sec. Type 2 shows a rise time within 0.15 sec; there is no peak and stabilization occurs immediately. Type 3 has a rise time greater than 0.15 sec, followed by a peak and stabilization within 0.5 sec. Type 4 has a rise time within 0.15 sec, no peak and no stabilization. Type 5 has a rise time greater than 0.15 sec, no peak and no stabilization. Type 6 has a rise time within 0.15 sec, a peak and stabilization after 0.5 sec. A sample was considered to be stabilized if it did not show a change greater than 20cm 3/sec after the rise and/or peak pressure was attained. Table 111 categorizes the 3 samples o f each subject according to the 6 cate gories. These samples were categorized by two observers working independently. The two judges agreed 99 % of the time. On those samples where there was initial disagreement, the two judges re-evaluated the air flow tracing and recate gorized it. After this, only 1 o f the samples could not be categorized. From
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Fig. 2. Air flow onset patterns constructed to best fit the air flow rate patterns pro duced by the subjects o f this study. 2 sec o f air flow rate are shown in the figure; however, only the initial second was analyzed for onset patterns.
407
Air Flow Onset and Variability
Table III. Analysis o f the initial 1-sec of air flow according to the 6 categories shown in figure 2 Subject
Category 1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33' 34
2
3
X
XX
X
XX
X
XX
XX
X
X
XX
X
X
4
5
XX
X
6
XXX
XXX
XXX X XXX XXX XX
X XXX XXX
X
X
X
XX
X X
XX
XXX XX
X
X
X
XXX X
XXX XX
X XX
X XXX X
XX
XXX X
XX X
XX
XX
X XX
X XX XXX
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The X ’s indicate the type to which the flow rate was assigned. 1 Only 2 of 3 samples could be classified; the 3rd sample did not fit the criteria o f any of the 6 categories.
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table II! it can be seen that the normal subjects demonstrate a fast rise time and quick stabilization o f the mean air flow rate. About one-third o f the onset patterns show a peak prior to stabilization. For the group with voice disorders, type 5 onset o f flow rate occurs most often, followed by type 6 and type 4. Closer examination of table III indicates that the 5 subjects with post-radia tion hoarseness (subjects 10 14) show a type 5 response 47 % o f the time. This group has 12/15 responses in types 4 and 5, indicating that lack o f stabilization o f flow rate is the predominant characteristic of the flow rate onset. The laryngeal cancer patient (subject-15) produced 3 o f the type 6 flow rate onset patterns; however, with only 1 subject, generalization to those with laryngeal cancer is not warranted. The group with unilateral paralysis showed an almost equal separa tion between types 4 and 5, again indicating that instability o f mean How rate was the predominant characteristic. O f the 3 subjects in the polypoid degeneration group (subjects 21 23), 1 showed 3 type 5 onset patterns, another 3 type 6 onset patterns, while the 3rd subject showed 3 different onset patterns. Although the underlying cause o f the disorder was the same for the 3 subjects, the clinical pictures o f air flow rate are different. This is also true for the group with dysphonia following intubation (subjects 16 20). The vocal nodule patient is consistent in his flow rate patterns to the point that he initiates air flow rapidly. The 2 hemilaryngectomees consis tently produce mean flow rate onset patterns which are slow to rise and do not stabilize. From the above analysis, it can be seen that patients with similar etiologies and diagnoses may differ with regard to their overall mean air flow rate or the onset pattern of the flow rate. More important, however, is the fact that only 6 o f the 75 samples produced by subjects with voice disorders fell into types 1,2, and 3, while only one o f the 27 normal samples was not in types 1, 2, or 3. Additional data may provide a more definitive description of the flow rate onset patterns, especially in the diagnostic categories having only 1 subject. From this study, it can be seen that the mean and standard deviation o f the air flow rate produced during phonation provide diagnostic information about a subject’s voice production patterns. In addition, the initial l-sec segment of airflow rate appears to contain clarifying diagnostic information which may be useful in the therapeutic restoration o f the voice.
Air flow patterns o f 34 subjects were analyzed in order to determine the sample-tosample variations and the onset patterns associated with a variety o f voice disorders. 3 samples of the vowel /a/ were sustained for 4 sec by each subject. 6 types of air flow onset patterns were identified: 4 of the patterns were found almost exclusively in those with disorders while 2 were almost exclusively associated with the normal talkers. Examination
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Summary
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of the steady-state portion o f the vowel samples indicated that normal talkers do not differ markedly from those with voice disorders in the sample-to-sample air flow fluctuations. The onset pattern, and the variations in the air flow may be valuable in the diagnosis and treatment o f voice disorders.
References Berg, J. van den: Physiology and physics o f voice production. Acta physiol, pharmac. neerl. 5; 40 55 (1956). Hirano, M .. Koike, Y., and Leden, H. von: Maximum phonation time and air usage during phonation. Folia phoniat. 20: 185 201 (1968). Isshiki, N .: Regulatory mechanism o f vocal intensity variation. J. Speech Hear. Res. 7: 17 29 (1964). Koike, Y.: Hirano, M ., and Leden, H. von: Vocal initiation: acoustic and aerodynamic investigations o f normal subjects. Folia phoniat. 19: 173 182 (1967). Winer. B .J.: Statistical principles in experimental design (McGraw-Hill, New York 1962). Yanagiliara. N. and Leden, H. von: Respiration and phonation. Folia phoniat. 19: 153 166 (1967). Yanagihara, TV., Koiki, Y.. and Leden. H. von: Phonation and respiration. Function study in normal subjects. Folia phoniat. 18: 323 340 (1966).
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Thomas Murry, PhD. Audiology and Speech Pathology Service. Veterans Administration Hospital, 3350 La Jolla Village Dr.. San Diego. C4 92161 (USA)
Air Flow Onset and Variability Thomas Murry and Linda K. Schmitke' Veterans Administration Hospital San Diego. Calif.
Previous investigations o f mean air flow rate in normal voices have demon strated its usefulness in determining glottal resistance (van den Berg, 1956; Isshiki, 1964). expiratory force ( Yanagihara et al., 1966), and vocal initiation characteristics (Koike et a i, 1967). In addition, aerodynamic relationships which pertain to laryngeal dysfunction (Yanagihara and von Leden, 1967; Hirano et al., 1968) have been found to be useful for diagnosing laryngeal pathology. The results o f these studies have shown that, in general, mean air flow rate in normal subjects has little relationship to mean fundamental frequency and has a moder ate relationship to vocal intensity, especially at the upper end of the phonational range, in patients with voice disorders, mean air flow rate has been generally related to the degree of glottal approximation, changes in vocal fold mobility and mass changes on the vocal folds. Mean air flow rates in pathological voices have been obtained ranging from 20 to 1,000 cm3/sec (Yanagihara and von Leden, 1967) while the normal mean air flow rates are approximately 110 cm3/ sec. In addition to knowing the mean air flow rate, information about the within sample and sample-to-sample variability in the flow rate would also appear to be diagnostically significant. If the instantaneous fluctuations in air flow rate were excessively large in persons with voice disorders, then mean air flow rate alone would appear to have limited diagnostic usefulness. Some fluctuation, however, in mean air flow rate can be expected and. in fact, may be related to the physiology of the laryngeal dysfunction. For example, if the air flow showed 1 The authors wish to acknowledge the support o f the Veterans Administration Hospi tal. San Diego, Calif. Mrs. Schmitke is now at the San Diego Speech, Hearing and Neurosensory Center.
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Received: August 18, 1975; accepted: September 10, 1975.
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402
significant variation within any one sample, and an overall high mean air flow rate with a large sample-to-sample difference, it may be hypothesized that the adequacy of glottic closure varies and, consequently, affects the mean air flow rate. There is little information on the sample-to-sample changes in the mean air flow rates o f normal talkers and persons with laryngeal dysfunctions. The pur pose of this study was to examine the variability o f mean air flow rate and the onset pattern of air flow in normal voices and in a variety o f dysphonias when the phonatory samples are produced under controlled conditions.
Method Subjects 9 subjects with normal voices and 25 subjects with various voice disorders participated in the study. Confirmation o f the diagnoses in the 25 subjects with voice disorders was based on the patient’s medical record and upon indirect laryngoscopy by an otolaryngolo gist. The normal subjects ranged in age from 19 to 37 years; the subjects with voice dis orders ranged from 32 to 77 years in age. Equipment Figure 1 is a block diagram o f the apparatus used to record the air flow and voice signals. Air flow rate was recorded through a face mask (Bennett. Benefit) connected to a pneumotachograph (Wiedeman, No. 20). The flow' rate was transduced into an equivalent voltage with a differential pressure transducer (Statham PM 97), amplified and recorded on a visicorder (Honeywell 1508C). The air flow channel was calibrated by passing a constant air supply through a rotameter and the pneumotachograph and recording the calibration trace on the visicorder. A linear calibration between 50 and 1200 cm3/sec was obtained.
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Fig. I. Block diagram of the apparatus used to record the air flow and voice signals and to monitor the sound level of the talker.
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The voice signal was sensed with a dynamic microphone (Electrovoice 664) located approxi mately 8 in. in front of the pneumotachograph. The voice signal was recorded on a magnetic tape recorder (Revox A-77) and a second channel o f the visicorder. A second microphone (Bruel & Kjaer 4131) was located 12 in. in front o f the pneumotachograph and connected to a sound-level meter (Bruel & Kjaer 2209). The patient used the sound-level meter to monitor the intensity o f his vocalizations. Procedure For this study, all subjects produced at least three phonatory samples of the sustained vowel la/ at their most comfortable level of voval production. To obtain these samples, each patient was seated comfortably with his face in the mask which was attached to the pneu motachograph. He was instructed to produce samples of the vowel /a/ at a comfortable level. The patient practiced until he could produce 4 or 5 consecutive 4-sec samples within 2 dB on the sound-level meter (C scale). The mean o f the samples to the nearest decibel was accepted as the target for the patient to reach during the test conditions. The patient then produced 3 -5 samples o f the vowel la/ at the target level while monitoring the sound-level meter. Initial overshoot of sound-level meter due to sudden onset o f phonation was not considered in selecting the final 3 samples for evaluation. Care was taken that no samples with obvious deviations in perceived pitch or quality were recorded. The tape-recorded signals were then processed through a graphic level recorder (Bruel & Kjaer 2305) to verify that the intensity, with the exception o f the first second o f each sample, did not vary by more than 2 dB. The first 4 sec o f three samples of /a/ for each subject were measured at 100-msec intervals. Thus, 40 points in time were measured for each phonatory sample. The means and standard deviations o f the air flow rates for the 1st sec and for the 2nd, 3rd and 4th sec combined were obtained.
Results The results o f this study are divided into two parts. The first part presents the results o f the 2nd, 3rd, and 4th seconds o f the phonatory samples (steadystate portion). The initial second (onset of phonation) is covered separately. The mean and standard deviation2 o f the air flow rates for the 2nd, 3rd, and 4th seconds of the 3 phonatory samples o f /a/ are shown in table I. These values were obtained from sampling the air flow tracing at '/io-sec intervals; thus, a total o f 30 values were obtained for each 3-sec sample. The final two columns show the overall mean and standard deviation for the combined 9 (3 samples X 3 sec) sec o f phonation. The normal subjects ranged from 57 to 183 cm3/sec in mean air flow rate, while those with voice disorders had a range from 139 to 819 cm3/sec. For any one normal subject there was as much as 55.5 cm3/sec
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! A Poisson variate transformation was applied to the data in order to accurately compare the standard deviations o f all subjects. This transformation may be used when the variances tend to be a function of the means. The transformation has the form SD = V sD (Winer, 1962). All standard deviations reported in this paper arc given in the Poisson transformation.
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Tablet. Mean and standard deviations o f the 2nd, 3rd and 4th seconds o f 3 samples o f the vowel /a/ and the overall mean and standard deviation (cm3/sec) o f the 3 samples Subject
X 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
Sample 2
Sample 1
57.50 66.50 157.50 96.00 138.00 120.00 143.00 150.50 144.00 231.52 201.00 139.50 159.50 240.00 210.00 812.00 295.00 343.00 611.50 298.00 291.50 145.00 245.00 165.00 218.50 218.00 293.00 217.00 191.50 307.00 220.00 256.00 162.00 288.50
SD 2.92 2.55 3.16 2.12 3.61 2.92 2.65 2.65 2.35 4.80 4.12 4.47 3.54 4.58 4.12 5.96 5.50 4.69 4.00 5.10 4.47 2.65 3.61 4.00 5.00 10.10 3.94 4.24 3.67 4.18 3.67 3.81 3.46 2.24
Overall
Sample 3
X
SD
X
SD
X
SD
88.00 95.00 170.00 87.50 152.50 120.00 122.00 144.50 145.00 265.50 267.00 207.50 160.50 206.50 243.00 853.50 289.50 405.00 540.00 337.00 264.00 141.00 254.00 167.00 184.50 309.00 277.00 163.00 237.00 303.00 223.50 260.50 158.50 449.00
2.00 1.87 4.08 1.73 3.46 2.65 2.45 3.16 2.35 5.10 5.92 3.87 3.61 3.94 4.95 6.00 6.82 5.36 5.20 3.67 3.39 3.54 3.67 2.83 4.06 8.37 3.74 6.32 3.87 4.36 3.72 4.53 4.74 4.12
96.00 97.00 183.50 77.00 134.50 144.50 97.50 154.00 143.00 250.00 255.00 217.00 155.00 229.50 207.50 891.00 279.00 365.00 606.50 350.00 270.00 144.00 237.50 170.00 165.00 315.00 297.00 247.50 234.00 295.00 217.50 268.50 142.50 432.50
1.87 2.00 4.02 3.00 2.92 2.12 2.12 3.39 3.08 4.58 5.52 3.87 3.00 4.18 4.08 5.10 5.87 4.53 6.52 2.65 4.06 2.65 2.74 3.32 3.46 8.63 3.54 5.48 3.87 4.47 3.81 4.42 3.16 5.24
80.50 86.17 170.33 86.83 141.67 128.17 120.83 149.67 144.00 249.00 241.00 188.00 158.33 225.33 220.17 852.17 287.83 371.00 586.00 328.50 275.15 143.33 245.50 167.33 189.33 280.67 289.00 209.17 220.83 301.67 220.33 261.67 154.33 390.00
4.50 4.13 3.61 3.09 3.09 3.76 4.77 2.18 1.00 4.13 5.93 6.50 1.71 4.14 3.38 6.29 2.85 5.61 6.32 5.21 3.80 1.44 2.87 1.59 5.20 7.37 3.25 6.54 5.04 2.47 1.73 2.52 3.22 9.40
difference from sample-to-sample and 161 cm3/sec for those subjects with voice disorders. Within any one sample, however, the normal subjects were highly stable, as evidenced by the within-sample standard deviations, as compared to the majority of the subjects with disorders.
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Means and standard deviations expressed in cubic centimeters per second and transformed according to Poisson variate transformation.
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Table II. Mean and standard deviation o f the 2nd, 3rd and 4th seconds o f each sub ject’s 3 samples o f the vowel grouped according to diagnostic category Group
n
X
SD
Range
Normals Post-radiation Laryngeal cancer Unilateral paralysis Polypoid degeneration Intubation dysphonia Vocal nodules Functional vocal abuse Hemilaryngectomy
9 5 1 5 3 5 1 3 2
123.13 212.33 220.17 485.10 221.33 227.10 220.83 261.22 272.17
5.67 6.15 4.43 15.32 8.34 7.40 5.15 6.40 12.89
57.50 183.50 139.50 255.00 210.00-243.00 279.00 891.00 141.00-291.50 163.00-315.00 191.50-237.00 217.00 307.00 142.50-449.00
The final two columns in the table show the mean and standard deviation o f the combined samples for each subject. Again the means for the normals are lower than those for the other subjects. Table II presents the mean air flow rate data grouped according to diagnosis. From table 11, it can be seen that the normal group has the lowest mean air flow rate and the unilateral vocal cord paralysis group has the highest mean air flow rate. The other groups, including the laryngeal cancer and vocal nodule patients (in which there is only 1 patient o f each type), show very similar mean air flow rates. Indeed, the ranges for these groups, with the exception o f functional vocal abuse groups, are also very similar. While the number for each group is small, there does not appear to be sufficient separation o f mean flow rate values to categorize the diagnosis on the basis o f mean air flow rate alone. Only the normals and the unilateral paralysis patients might be distinguished sufficiently on the basis o f flow rate alone. With regard to the variability found in the samples, the standard deviations indicate that those individuals with functional vocal abuse have the smallest sample-to-sample variation, even smaller than the normals. Thus, while their mean air flow rate was similar to the other groups, their standard deviation was smaller than all other groups. In addition to examining the steady-state portion o f the vowel samples, the initial 1 sec was evaluated in terms o f the onset of the air flow. After one o f the experimenters drew contours o f best fit for all flow samples, 6 composite groupings were derived. All but 1 o f the 102 samples produced by the subjects were assigned to 1 of the 6 categories. Figure 2 shows the 6 general categories o f mean air flow rate onset. Type 1 has a rise time within 0.15 sec, a peak and
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Means, standard deviations and ranges expressed in cubic centimeters per second and transformed according to Poisson variate transformation.
Murry ¡Schmitke
406
stabilizes within 0.5 sec. Type 2 shows a rise time within 0.15 sec; there is no peak and stabilization occurs immediately. Type 3 has a rise time greater than 0.15 sec, followed by a peak and stabilization within 0.5 sec. Type 4 has a rise time within 0.15 sec, no peak and no stabilization. Type 5 has a rise time greater than 0.15 sec, no peak and no stabilization. Type 6 has a rise time within 0.15 sec, a peak and stabilization after 0.5 sec. A sample was considered to be stabilized if it did not show a change greater than 20cm 3/sec after the rise and/or peak pressure was attained. Table 111 categorizes the 3 samples o f each subject according to the 6 cate gories. These samples were categorized by two observers working independently. The two judges agreed 99 % of the time. On those samples where there was initial disagreement, the two judges re-evaluated the air flow tracing and recate gorized it. After this, only 1 o f the samples could not be categorized. From
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Fig. 2. Air flow onset patterns constructed to best fit the air flow rate patterns pro duced by the subjects o f this study. 2 sec o f air flow rate are shown in the figure; however, only the initial second was analyzed for onset patterns.
407
Air Flow Onset and Variability
Table III. Analysis o f the initial 1-sec of air flow according to the 6 categories shown in figure 2 Subject
Category 1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33' 34
2
3
X
XX
X
XX
X
XX
XX
X
X
XX
X
X
4
5
XX
X
6
XXX
XXX
XXX X XXX XXX XX
X XXX XXX
X
X
X
XX
X X
XX
XXX XX
X
X
X
XXX X
XXX XX
X XX
X XXX X
XX
XXX X
XX X
XX
XX
X XX
X XX XXX
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The X ’s indicate the type to which the flow rate was assigned. 1 Only 2 of 3 samples could be classified; the 3rd sample did not fit the criteria o f any of the 6 categories.
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table II! it can be seen that the normal subjects demonstrate a fast rise time and quick stabilization o f the mean air flow rate. About one-third o f the onset patterns show a peak prior to stabilization. For the group with voice disorders, type 5 onset o f flow rate occurs most often, followed by type 6 and type 4. Closer examination of table III indicates that the 5 subjects with post-radia tion hoarseness (subjects 10 14) show a type 5 response 47 % o f the time. This group has 12/15 responses in types 4 and 5, indicating that lack o f stabilization o f flow rate is the predominant characteristic of the flow rate onset. The laryngeal cancer patient (subject-15) produced 3 o f the type 6 flow rate onset patterns; however, with only 1 subject, generalization to those with laryngeal cancer is not warranted. The group with unilateral paralysis showed an almost equal separa tion between types 4 and 5, again indicating that instability o f mean How rate was the predominant characteristic. O f the 3 subjects in the polypoid degeneration group (subjects 21 23), 1 showed 3 type 5 onset patterns, another 3 type 6 onset patterns, while the 3rd subject showed 3 different onset patterns. Although the underlying cause o f the disorder was the same for the 3 subjects, the clinical pictures o f air flow rate are different. This is also true for the group with dysphonia following intubation (subjects 16 20). The vocal nodule patient is consistent in his flow rate patterns to the point that he initiates air flow rapidly. The 2 hemilaryngectomees consis tently produce mean flow rate onset patterns which are slow to rise and do not stabilize. From the above analysis, it can be seen that patients with similar etiologies and diagnoses may differ with regard to their overall mean air flow rate or the onset pattern of the flow rate. More important, however, is the fact that only 6 o f the 75 samples produced by subjects with voice disorders fell into types 1,2, and 3, while only one o f the 27 normal samples was not in types 1, 2, or 3. Additional data may provide a more definitive description of the flow rate onset patterns, especially in the diagnostic categories having only 1 subject. From this study, it can be seen that the mean and standard deviation o f the air flow rate produced during phonation provide diagnostic information about a subject’s voice production patterns. In addition, the initial l-sec segment of airflow rate appears to contain clarifying diagnostic information which may be useful in the therapeutic restoration o f the voice.
Air flow patterns o f 34 subjects were analyzed in order to determine the sample-tosample variations and the onset patterns associated with a variety o f voice disorders. 3 samples of the vowel /a/ were sustained for 4 sec by each subject. 6 types of air flow onset patterns were identified: 4 of the patterns were found almost exclusively in those with disorders while 2 were almost exclusively associated with the normal talkers. Examination
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Summary
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of the steady-state portion o f the vowel samples indicated that normal talkers do not differ markedly from those with voice disorders in the sample-to-sample air flow fluctuations. The onset pattern, and the variations in the air flow may be valuable in the diagnosis and treatment o f voice disorders.
References Berg, J. van den: Physiology and physics o f voice production. Acta physiol, pharmac. neerl. 5; 40 55 (1956). Hirano, M .. Koike, Y., and Leden, H. von: Maximum phonation time and air usage during phonation. Folia phoniat. 20: 185 201 (1968). Isshiki, N .: Regulatory mechanism o f vocal intensity variation. J. Speech Hear. Res. 7: 17 29 (1964). Koike, Y.: Hirano, M ., and Leden, H. von: Vocal initiation: acoustic and aerodynamic investigations o f normal subjects. Folia phoniat. 19: 173 182 (1967). Winer. B .J.: Statistical principles in experimental design (McGraw-Hill, New York 1962). Yanagiliara. N. and Leden, H. von: Respiration and phonation. Folia phoniat. 19: 153 166 (1967). Yanagihara, TV., Koiki, Y.. and Leden. H. von: Phonation and respiration. Function study in normal subjects. Folia phoniat. 18: 323 340 (1966).
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Thomas Murry, PhD. Audiology and Speech Pathology Service. Veterans Administration Hospital, 3350 La Jolla Village Dr.. San Diego. C4 92161 (USA)
