Mean Airflow Rate Research Articles

Relationship between power spectra of breath sounds and inspiratory flows at different frequencies

Regional ventilation and changes in airway caliber have been studied by analysis of breath sounds. The aim of this study was to find which frequency band is most suitable for such purposes. The subjects were 19 healthy men. Breath sounds at 6 sites on the chest wall, airflow rate at the mouth, and ECG were digitized and recorded for 30 seconds. Power spectra of breath sounds at various frequency bands (10-50 Hz, 50-100 Hz, 100-150 Hz, ...., 950-1000 Hz) were calculated with a fast-Fourier transform (FFT) for every block of 512 points (102.4 msec), and mean airflow rates for the blocks were calculated. Data recorded during inspiration when airflow ranged between 0.5 L/s and 3 L/s were analyzed. For frequency bands from 150 Hz to 850 Hz the logarithms of the power spectra were linearly correlated with the logarithms of the airflow rates, and the correlation coefficients exceeded 0.8, but for lower frequency bands the correlations were poor. When the data contaminated by heart sounds and those recorded late in inspiration were excluded the correlations at frequency bands below 150 Hz improved. The slope of log (power)/log (flow) was about 4 for the bands from 100 to 300 Hz, but it became steeper (4 to 6) for higher frequency bands. This means that the power spectra were proportional to the fourth power of the airflow rate for bands below 300 Hz, but the relation was from the fourth to the sixth power for higher frequency bands.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical analysis of presbylarynx—Vocal fold atrophy in elderly individuals

Objective The proportion of elderly Japanese is increasing significantly and aging society greatly influences the medical services. The number of elderly patients who visited out Voice Outpatient Clinic has been increasing in recent years. The aim of the present study was to analyze the trend in the number of patients with aging-related vocal fold atrophy, and to assess the characteristics of senile change of vocal function. Methods A retrospective review of the 1999–2005 medical records of patients aged ≥65 years was conducted, and patients with presbylarynx were analyzed. We evaluated age, sex, occupation, maximal phonation time (MPT), and mean airflow rate (MFR) during comfortable phonation to assess the physiological characteristics of senile change of vocal function. We compared MFR of presbylarynx with those of normal elderly person. Results The number of patients aged ≥65 who visited our clinic in the 7-year study period was 361, and 72 (20%) were diagnosed with vocal fold atrophy. They included 47 (65%) men and 25 (35%) women, with a mean age of 71 years (range, 65–89). Among these patients, 27 (38%) were still employed at the time of consultation, while 17 (24%) were retired, at least 26 jobs required voice skills; and 15 patients (21%) were involved in singing and recitation of poems. MPT correlated negatively with age, while MFR correlated positively with age. Conclusion The number of elderly patient with vocal fold atrophy increased gradually almost every year. The male patients account for 65%. Thirty-three percent of patient of the present study with presbylarynx were still in the workforce. MFR correlated positively and significantly with age. MFR was higher in presbylarynx than normal elderly person.

The Effect of Maxillary Multidirectional Movement on Nasal Respiration

Deformities of the maxilla may exist on all planes, and we treat these problems by mobilizing and repositioning the maxilla on all planes. Some authors have examined the effects of maxillary movement on the nasal airway. In clinical, practice, active anterior rhinomanometry is the most reliable and frequently used method to assess nasal respiratory function. The purpose of this study was to evaluate changes in nasal airflow and nasal airway resistance after maxillary movement performed by active anterior rhinomanometry. We studied 25 patients (18 female patients and 7 male patients; aged 16-30 years) in this clinical trial. Three days before surgery and 6 months after surgery, after a rest period of 30 minutes, active anterior rhinomanometry with a tube was performed at a fixed transnasal pressure of 150 Pa. The surgical treatment plan included bimaxillary surgery consisting of a 1-piece Le Fort I osteotomy combined with a bilateral sagittal split osteotomy. Mean and median total nasal airflow and nasal resistance rate were calculated before surgery and after surgery and compared by use of SPSS software (version 11.5; SPSS, Chicago, IL) and paired t test. An increase in nasal airflow (P = .009) and a decrease in nasal resistance (P = .022) were observed in the maxillary impaction and advancement group. In the maxillary impaction and setback group, there was a significant difference in nasal resistance changes (P = .027); however, postsurgical nasal airflow compared with presurgical values showed no statistically significant difference (P = .244). Impaction and advancement of the maxilla can improve nasal respiratory function, but maxillary impaction and setback reduce nasal respiratory function. Hence candidates for maxillary impaction and setback must be informed about decreased nasal respiratory function.

Lower Thoracic Spinal Cord Stimulation to Restore Cough in Patients With Spinal Cord Injury: Results of a National Institutes of Health–Sponsored Clinical Trial. Part I: Methodology and Effectiveness of Expiratory Muscle Activation

DiMarco AF, Kowalski KE, Geertman RT, Hromyak DR. Lower thoracic spinal cord stimulation to restore cough in patients with spinal cord injury: results of a National Institutes of Health–sponsored clinical trial. Part I: methodology and effectiveness of expiratory muscle activation. Objective Evaluation of the capacity of lower thoracic spinal cord stimulation (SCS) to activate the expiratory muscles and generate large airway pressures and high peak airflows characteristic of cough, in subjects with tetraplegia. Design Clinical trial. Setting Inpatient hospital setting for electrode insertion; outpatient setting for measurement of respiratory pressures; home setting for application of SCS. Participants Subjects (N=9; 8 men, 1 woman) with cervical spinal cord injury and weak cough. Interventions A fully implantable electrical stimulation system was surgically placed in each subject. Partial hemilaminectomies were made to place single-disk electrodes in the epidural space at the T9, T11, and L1 spinal levels. A radiofrequency receiver was placed in a subcutaneous pocket over the anterior portion of the chest wall. Electrode wires were tunneled subcutaneously and connected to the receiver. Stimulation was applied by activating a small portable external stimulus controller box powered by a rechargeable battery to each electrode lead alone and in combination. Main Outcome Measures Peak airflow and airway pressure generation achieved with SCS. Results Supramaximal SCS resulted in high peak airflow rates and large airway pressures during stimulation at each electrode lead. Maximum peak airflow rates and airway pressures were achieved with combined stimulation of any 2 leads. At total lung capacity, mean maximum peak airflow rates and airway pressure generation were 8.6±1.8 (mean ± SE) L/s and 137±30 cmH 2O (mean ± SE), respectively. Conclusions Lower thoracic SCS results in near maximum activation of the expiratory muscles and the generation of high peak airflow rates and positive airway pressures in the range of those observed with maximum cough efforts in healthy persons.

Turbulence effects on the discharge coefficient and mean flow rate of wind-driven cross-ventilation

This experimental study uses a wind tunnel and scale model to investigate turbulence effects on the discharge coefficient and mean flow rate of wind-driven cross-ventilation. The approaching flows include low turbulence smooth flow and grid-generated turbulent flow. Two different cross-ventilation configurations are considered in this study: (1) two opposite walls, each with one opening, and (2) two adjacent walls, each with one opening. The discharge coefficients of different flow conditions are determined by a fan technique. It is found that the discharge coefficient is a function of Reynolds number, wind incidence angle and direction of air flow (inhale or exhale), but independent of external turbulence intensity and wall porosity. However, because the leeward pressure is affected by external turbulence, the internal pressure and inlet velocity are dependent on external turbulence when the openings are on the opposite walls. The experimental results also verify that internal pressure and mean air flow rate can be predicted once the external pressure distribution and opening areas are known, regardless of whether the openings are on opposite walls or on adjacent walls.

Optimization of the Production of Quicklime by Calcination in Rotary Kilns

It well known that the operational conditions of rotary kilns affect strongly the quality of quicklime produced. This work presents a study about parametric optimization of rotary kilns for quicklime production (CaO) from thermal decomposition of calcite limestone (CaCO3). The approach used is based on the technique of design of experiments (DOE) to identify the most significant variables which affect the quality of oxide and, in addition, to determine better conditions of production. An experimental setup in laboratory scale was build in order to carry out the experiments. Calcination temperature, calcination time, rotation speed, particle mean diameter, heat flow and air flow rate were evaluate using a fractional factorial design. The parametric optimization shows that the raise of time and temperature of calcinations produces an increase of free CaO terms. However this operation is not useful due to sintering process observed in the BET surface area results. A correlation between quicklime reactivity and specific surface area could be established, in way that reactive quicklimes presented bigger areas. Finally, it was possible to determine the best conditions of quicklime production and to estimate a quadratic model by using a central composite design and a like surface response model. It was found that the best region of operation is about 900oC and 45 minutes of calcination time.

A “Fenestration Approach” for Arytenoid Adduction Through the Thyroid Ala Combined With Type I Thyroplasty

To develop and evaluate the voice outcomes of an approach of arytenoid adduction (AA) through a fenestration of the thyroid ala for unilateral vocal cord paralysis. Twelve consecutive patients with severe unilateral vocal cord paralysis, whose maximum phonation times (MPTs) were less than or equal to 5 seconds, underwent laryngoplasty using an approach of AA performed through a fenestration of the thyroid ala combined with type I thyroplasty. Two surgical windows were made in the lower part of the thyroid ala. The anterior window was for typical type I thyroplasty, and the posterior window was for AA. AA was performed by pulling the lateral cricoarytenoid muscle (LCA) (5 patients) or muscular process (7 patients) through the posterior fenestration in the contractile direction of the LCA without releasing the cricoarytenoid joint. The operation was performed under local anesthesia with sedation except in two patients who underwent general anesthesia using a laryngeal mask. The vocal cord medialization was confirmed endoscopically during the operation. For all patients, the MPT and mean airflow rate (MFR) were measured before and after the operation. The postoperative voices were analyzed using shimmer and jitter. All patients achieved a MPT of over 12 seconds. The MFR, which ranged from 340 to 1902 mL/second before the operation, improved to less than 200 mL/second, except in one patient whose MFR was 210 mL/second. Shimmer and jitter improved significantly after the operation. Perceptual evaluation using the GRBAS (grade, roughness, breathiness, aesthenia, strain) scale also improved significantly. A fenestration-based approach simplified the combination of AA and type I thyroplasty because the two treatments could be performed in the same operating field and provided good voice improvement. Pulling the AA braid in the contractile direction of the LCA and endoscopic vocal cord observation during surgery may have contributed to the positive results.

Improving natural ventilation in combined solar house with solar chimney and solar water collector

AbstractThe paper studies a combined solar house with a solar chimney and a solar water collector. Theoretical analyses were carried out to investigate natural ventilation in the solar house, compared with that in the individual chimney ventilation system under the same conditions. It was found that the proposed combined ventilation system improved the ventilation. When the mean solar radiation during a day from 8:00 to 18:00 h is 550 W m−2, the mean airflow rate in the combined ventilation system reaches 0·32 m s−1, which is 18·5% higher than that (0·27 m s−1) in the individual chimney ventilation system under the same conditions. Furthermore, it was found that the effect of night ventilation on the combined solar house is better, although less energy is drawn out from the room by comparing chimney airflow temperatures and rates when the dampers are open after 18:00 h, with those when the dampers are open day and night. It can be vital to housing conditions and factories which work during the night to cr...

Multi-zonal air flow rates in residences in Boston, Massachusetts

In spite of the importance of interzonal air flow for indoor air quality assessment, few studies have characterized these flows. As part of the Boston Exposure Assessment in Microenvironments (BEAM) Study, air flow rates were estimated within 45 residences in the Boston area, most over two seasons. Thirty-five residences had basements, 11 of which also had attached garages, and 10 other residences had common apartment hallways. Air flow rates between zones were calculated using tracer gases (PFTs and SF6) and mass-balance models. Mean air flow rates from the basement to the occupied zone were significantly higher in the winter (174 m 3 h −1) than in the summer (67 m 3 h −1). The mean percent of the total air flow within the occupied zone of the residence from the basement was 26% (SD=34%) in the summer and 47% (SD=26%) in the winter while the mean percent from apartment hallways was 22% (SD=33%). Residences with garages attached to the basement had higher air flow rates to the adjacent zone (means from 50 to 887 m 3 h −1) than those with garages attached directly to the occupied zone (means from 1 to 65 m 3 h −1). These data provide a basis for modeling the contribution of indoor sources to concentrations in occupied zones.

Examination of Atelocollagen Implantation Validity by Maximum Phonation Time and Mean Airflow Rate

片側性声帯麻痺に対する外科的治療法に関して，声帯内アテロコラーゲン注入術は他の術式と比較し外来手術として簡便に行えるという利点がある。一方，効果の限界や異種タンパクとしての問題も指摘されている。今回われわれは術前後における最長発声持続時間および平均呼気流率の変化から，注入術の有効性についての検討と術前の各値から術後効果予測の可否についての検討を行った。術後に最長発声持続時間が1秒以上改善し，なおかつ平均呼気流率が術前より減少している症例を有効と評価した。注入術を施行した16症例中10例で治療は有効であり，症例群としての各値はともに有意に改善したが，術前値と手術効果の有無について統計学的な関連性は認められなかった。

ポリープ様声帯に片側反回神経麻痺が合併したことで呼吸困難を来した1例

We reported on a case of Reinke's edema with dyspnea following resection of the right recurrent laryngeal nerve during surgery for thyroid papillary carcinoma. A 55-year-old female, who was a smoker, presented with a greater than 20-year-history of hoarseness of the voice, without dyspnea. She was diagnosed as having type III Reinke's edema according to Yonekawa's classification of Reinke's edema.She had undergone total thyroidectomy with modified selective neck dissection for thyroid papillary carcinoma involving right vocal cord, at the Department of Surgery, Kitasato University Hospital. The right vocal cord was fixed at the paramedian position. The patient had developed dyspnea transiently for a few days. Subsequently, she began to suffer from dyspnea upon exertion or when she developed a cold. The patient was diagnosed as having Reinke's edema. The dyspnea disappeared after endolaryngeal microsurgery. The right vocal cord was fixed at the median position, the mean air flow rate improved, and the fundamental frequency of her voice was higher than before the operation.

Effects of smoking on respiratory capacity and control

The purpose of this study was to provide information concerning the possible early effects of smoking on measures of respiratory capacity and control in young adult female smokers vs. nonsmokers. In particular, maximum performance test results (vital capacity and maximum phonation time) and measures of air pressures and airflows during voiceless, stop‐plosive productions were analysed. Subjects were 45 female nonsmokers and 30 female smokers (total n = 75) between the ages of 18–30 years. For the purposes of this study, a smoker was defined as any subject who, at the time of this study, had smoked at least two cigarettes per day for at least 1 year. All of the subjects in the nonsmoker category were those who, at the time of this study, did not smoke and who had not smoked for at least 5 years prior to the study. Vital capacity measures were conducted using a hand‐held digital spirometer, while maximum phonation productions and voiceless, stop‐plosive pressures and flows were recorded and measured using the Aerophone II Model 6800 (Kay Elemetrics Corp., Lincoln Park, NJ). Results showed significantly lower vital capacities and maximum phonation times in smokers vs. nonsmokers. The maximum phonation time task was also produced with significantly higher mean airflow rates in smokers than nonsmokers. In addition, the smokers were observed to produce significantly greater peak and mean pressures during the voiceless stop‐plosive task than the nonsmokers. A weak, but significant correlation was observed between the number of days the subject had smoked and the mean pressure produced during the voiceless, stop‐plosive task. The findings of reduced respiratory capacity and control in smokers may be associated with factors such as increased bronchial reactivity secondary to exposure to cigarette smoke and/or mild airway obstruction, increased airflow secondary to increased glottal gap size during phonation, and increased vocal fold mass and/or inefficiency in vocal fold closure. The findings of this study indicate that decrements in respiratory capacity and control may occur even in relatively young smokers who have only been smoking for a comparatively short time

Immediate Recurrent Laryngeal Nerve Reconstruction and Vocal Outcome

The objective of this prospective study was to assess the long-term effects of immediate reconstruction of the recurrent laryngeal nerve (RLN) during thyroid cancer extirpation on postoperative phonatory function. The subjects were 22 patients with advanced thyroid cancer who underwent resection of the primary lesion and involved RLN. RLN paralysis was seen in 12 patients preoperatively and involvement of the RLN was noted intraoperatively in 10. Immediate reconstruction of the RLN was performed on eight patients using the great auricular nerve and one underwent direct anastomosis of the RLN stumps (group I). Nine patients opted not to have phonosurgical procedures (group II). The remaining four had arytenoid adduction immediately after cancer extirpation (group III). Phonatory function (stroboscopy, maximum phonation time [MPT], mean airflow rate [MFR], harmonics-to-noise ratio [HNR], jitter, and shimmer) was followed for at least 9 months. Minimal or no glottal gap during phonation was observed in six patients in group I, whereas the patients in group II had a large gap along the entire fold. HNR, MPT, and MFR were significantly better in group I (17.7 +/- 3.6 dB, 15.1 +/- 6.3 s, and 100 +/- 32 mL/s, respectively) than in group II (12.1 +/- 2.9 dB, 5.4 +/- 3.1 s, and 430 +/- 207 mL/s, respectively). Patients in group III had a gap of varying degrees along the membranous fold. Although HNR, shimmer, and MPT in group III were comparable to group I, the other parameters were less favorable than in group I. Immediate RLN reconstruction at the time of thyroid cancer extirpation can provide excellent postoperative phonatory function.

Autonomic Nervous System Dysregulation: Breathing and Heart Rate Perturbation During Wakefulness in Young Girls with Rett Syndrome

This study characterizes cardiorespiratory dysregulation in young girls with MECP2 mutation-confirmed Rett syndrome (RS). Respiratory inductance plethysmography of chest/abdomen and ECG was obtained during daytime wakefulness in 47 girls with MECP2 mutation-confirmed RS and 47 age-, gender-, and ethnicity-matched controls (ages 2-7 y). An in-home breath-to-breath and beat-to-beat characterization was conducted and revealed that breathing was more irregular, with an increased breathing frequency, mean airflow, and heart rate in RS versus controls. There was a decreased correlation between normal breathing and heart rate variability, and an exaggerated increase in heart rate response to breathholds in RS versus controls. We conclude that girls with RS have cardiorespiratory dysregulation during breathholds as well as during "normal" breaths and during breaths before and subsequent to breathholds. This dysregulation may offer insight into the mechanisms that render girls with RS more vulnerable to sudden death.

A Novel Treatment for Hypophonic Voice: Twang Therapy

A hypophonic voice, characterized perceptually as weak and breathy, is associated with voice disorders such as vocal fold atrophy and unilateral vocal fold paralysis. Although voice therapy programs for hypophonia typically address the vocal folds or the sound source, twang voice quality was examined in this study as an alternative technique for increasing vocal power by altering the epilarynx or the sound filter. This study investigated the effect of twang production on physiologic, acoustic, and perceived voice handicap measures in speakers with hypophonia. This prospective pilot study compared the vocal outcomes of six participants with hypophonia at pre- and posttreatment time points. Outcome measures included mean airflow rate, intensity in dB sound pressure level (SPL), maximum phonation time, and self-report of voice handicap. All subjects improved in at least three of the four vocal outcome measures. Wilcoxon signed-rank test of paired differences revealed significant differences between pre- and posttherapy group means for airflow rate, SPL, and Voice Handicap Index scores. The twang voice quality as a manipulation of the sound filter offers a clinical complement to traditional voice therapies that primarily address the sound source.

声帯内自家脂肪注入術の臨床・組織学的研究

Injection laryngoplasty is a reliable surgical procedure to correct laryngeal incompetence caused by vocal fold paralysis. Although autologous fat has become a popular injection material in recent times, there are numerous problems that need to be addressed in its application in laryngoplasty; such as, injection site of the vocal fold, quantity of injection material, possibility of improvement for glottal gap, and resorption of injected autologous fat. The purpose of this study is to investigate the problems of autologous fat injection in laryngoplasty.The clinical study involved 31 patients with unilateral vocal fold paralysis who had received treatment at the Kurume University Hospital between 2000 and 2003. The pathological study was comprised of 23 patients whose autologous fat harvested by liposuction was utilized as injection material during laryngoplasties between 2000 and 2005.In patients with a small degree of vocal fold bowing, autologous fat was injected locally into the thyroarytenoid muscle lateral to the oblong fovea of the arytenoid cartilage. As a result, the glottal gap decreased and postoperative voice functions, maximum phonation time (MPT) and mean airflow rate during phonation over comfortable duration (MFRc) improved. In patients with a large degree of vocal fold bowing, the autologous fat was injected not only into the thyroarytenoid muscle lateral to the ob-long fovea of the arytenoid cartilage but also into the thyroarytenoid muscle at the membranous portion of the vocal fold. As a result, the glottal gap decreased and postoperative voice functions, MPT and MFRc improved.The fat cell membranes had not been damaged during liposuction harvesting or microinjection by our technique. The diameters of fat cells ranged from 41.3±8-117.1±15.2μm. A few patients with large diameter fat cells showed less improvement compared to those with smaller diameters for the postoperative voice functions, MPT, MFRc, and pitch perturbation quotient (PPQ).These results indicate that fat injection into the thyroarytenoid muscle lateral to the oblong fovea of the arytenoid cartilage produced good postoperative voice function and this procedure can improve a large degree of glottal gap. Resorption of autologous fat may be related to not only the size and density of fat cells but also their proliferation.

Objective Voice Measures in Nonsinging Patients With Unilateral Superior Laryngeal Nerve Paresis

The clinical value of objective voice measures in nonsinging patients with superior laryngeal nerve dysfunction is unknown. In this study, patients with symptomatic unilateral superior nerve paresis were evaluated for maximum phonation time, frequency range of phonation, and mean flow rate. Patients with coexisting pathology, bilateral superior nerve paresis, and those with recurrent laryngeal nerve paresis were excluded from this analysis. A total of 35 nonsinging patients, 14 men and 21 women, with unilateral superior laryngeal nerve paresis were examined between 1999 and 2002. The severity of superior laryngeal nerve paresis ranged from 25% to 85% of normal recruitment with a mean of 70% superior laryngeal nerve recruitment in men and 65% in women by electromyography. In both men and women with superior laryngeal nerve paresis, the maximum phonation time and frequency range of phonation were decreased and the mean air flow rate was increased when compared with normal population values. The jitter percent, shimmer percent, and noise-to-harmonic ratio were also increased in patients when compared with normative data. Selected objective voice measures are abnormal in voice patients with superior laryngeal nerve paresis, which suggests that the measures may be useful as outcomes measures after therapy. More research is encouraged.

Vocal Fold Augmentation with Calcium Hydroxylapatite (CaHA)

The purpose of this study is to investigate the feasibility of using an injectable needle electrode to guide hyaluronic acid (HA) vocal fold injection (VFI) during laryngeal electromyography (LEMG) for unilateral vocal fold paralysis (UVFP).Prospective study.From March to June 2010, 20 UVFP patients received LEMG examination at our clinic. Before completion of LEMG, 1.0 cc of HA (Restylane Perlane®; Q-Med, Uppsala, Sweden) was injected via a 26-gauge monopolar injectable needle electrode into paralyzed thyroarytenoid muscle. After injection, 20 patients completed 3-months follow-up and 16 patients completed 6-months follow-up. The data before, 1 week, 3 months, and 6 months after injection, including the normalized glottal gap area (NGGA) from videostroboscopy, maximal phonation time (MPT), mean airflow rate (MAFR), phonation quotient (PQ), perceptual evaluation of voice (grade, roughness, breathiness, asthenia, strain [GRBAS] scale), Voice Handicap Index (VHI), and self-grading of choking (grade 1–7), were analyzed by the Wilcoxon signed rank test.All of the patients completed the procedure without complications. After injection, mean NGGA was significantly reduced from 8.28 units to 0.52 units (1 week), 1.79 units (3 months), and 1.36 units (6 months). The mean MPT was prolonged from 5.66 seconds to 11.73, 11.25, and 11.93 seconds, respectively. VHI was reduced from 76.05 to 38.10, 37.40 and 35.00, respectively. Other analyzed data (PQ, MAFR, GRBAS scale, and choking severity) also showed statistically significant improvement.LEMG-guided HA VFI provides UVFP patients with neuromuscular function evaluation and treatment in one step. This clinical technique is feasible, and the short-term results are satisfactory.

Study of mixed convective heat transfer in a sintered porous channel

This investigation experimentally elucidates mixed heat convection in a rectangular channel with porous medium, and analyzes the cooling performance of electronics. The test sections are sintered copper granules with dimensions of 5 × 5 × 1 cm and average diameters of 0.704 mm and 1.163 mm. A porous channel is heated using air as the working fluid. The measured variables include the heat flux on the heat surface, the local wall temperature in the flow direction, the inlet/outlet pressure, and the flow rate. The boundary condition is that the heating surface of the lower plate of the test section is heated by an isothermal heat flux, while the other three sides are thermally insulated; the heat flux is between 0.23 and 1.86 Watt/cm2. The mean air flow rate within a porous channel is between 0.3 and 4.0 m/s. The thermally developed region and the fully developed region are measured. This experiment is directed at understanding the influence on heat transfer based on the diameter of the sintered copper granules, Reynolds number, and heat flux. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(2): 64–77, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20050

Reliability and applicability of aerodynamic measures in dysphonia assessment

Aerodynamic measures are frequently used to analyse and document pathological voices. Some normative data are available for speakers from the English‐speaking population. However, no data are available yet for Chinese speakers despite the fact that they are one of the largest populations in the world. The high variability of aerodynamic measures between and within subjects raises the issue of reliability and usefulness of this procedure in discriminating between normal and pathological voices. This study aimed to investigate the use of mean airflow rate and sub‐glottal pressure in predicting normal and pathological voices. It also aimed to determine whether a higher number of repeated airflow measures would provide a better representation of the normative data in distinguishing normal from abnormal voices. The study provided a small set of preliminary normative data for Chinese speakers. Aerodynamic measures were collected from 56 Cantonese female adults using a Kay Elemetrics Aerophone II. The results showed that the accuracy in predicting a voice to be dysphonic or normal using aerodynamic measures was as high as 91.1%. The accuracy was found to improve when the number of measurements for each aerodynamic parameter was increased from three to five. The overlapping of data between the dysphonic and non‐dysphonic groups, however, suggests that the aerodynamic measures should be used as an adjunct to assessment of voice disorders rather than as a diagnostic tool alone.