Peak Airflow Research Articles

Acoustic characteristics of voice source for pathological voices: Some case studies.

The aim of this study is to examine the voice source signal of pathological voices. Pathological cases of vocal nodules, polyps, paralysis, malignancy, and laryngitis have been investigated. Some pre‐ and postoperative cases have also been studied. The sustained vowel /a/ of the subject has been recorded. The acoustic signal has been analyzed using an inverse filtering technique to obtain the voice source signal (derivative of glottal air flow). The voice source signal is displayed and marked for detailed examination. Acoustic recording, analysis, and marking is done using a VAGHMI system. For each type of pathology, certain consistent features deviating significantly from the normal cases have been noted in the voice source signal. For example, occurrence of double peak during the open phase, prolongation of the interval near glottal air flow peak, absence of clearly defined negative peak near epoch, etc. Interpretation of the voice source signal in terms of the vocal fold vibratory pattern and pathology has been attempted. Such an interpretation is validated against direct laryngoscopic observation where ever available. This on‐going study suggests the possibility of differential diagnosis of the vocal fold pathology by acoustic analysis of vowel sound.

Effects of vagal and laryngeal afferents on apnoeic response to serotonin in cats

Intravenous serotonin (5-HT) elicits apnoea followed by subsequent, shallow tachypnoea. The present study was designed to ascertain whether laryngeal afferents play a role in the respiratory reflex response. Administration of 5-HT into the femoral vein (i.v.) or to the laryngeal artery (lar. art.) in anaesthetized, spontanously breathing cats caused an expiratory apnoea that was significantly reduced (i.v.) or abolished (lar. art.) by bilateral midcervical vagotomy. Subsequent bilateral division of the superior laryngeal nerves (SLNs) did not affect the magnitude of apnoea on i.v. administration. Supranodose vagotomy abolished the occurrence of post-serotonin apnoea following i.v. injection, which is consistent with earlier results. During the phase of rapid, shallow breathing the peak respiratory airflows were significantly increased on i.v. 5-HT injection in all neural states of cats, whereas laryngeal artery administration failed to produce a significant change in respiratory airflows from baseline. Serotonin significantly increased breathing frequency in the intact and denervated (vagus and SLN cut bilaterally) cats independent of the route of injection. The results show that serotonin affects the respiratory pattern with large contribution of pulmonary vagal but not laryngeal afferents. However, the occurrence of the expiratory apnoea was related to large extent to the integrity of the infranodose vagi.

Physiological characteristics of the supported singing voice. A preliminary study

The purpose of this study was to develop a definition of the supported singing voice based on physiological characteristics by comparing the subjects' concepts of a supported voice with objective measurements of their supported and unsupported voice. This preliminary report presents findings based on data from eight classically trained singers. Subjects answered questions about their concepts of the characteristics of the supported singing voice and how it is produced. Samples of the supported and unsupported singing voice produced at low, medium, and high pitches at a comfortable loudness level were collected for acoustic, spectral, airflow, electroglottographic, air volume, and stroboscopic analyses. Significant differences between the supported and unsupported voice were found for sound pressure level (SPL), peak airflow, subglottal pressure (Ps), glottal open time, and frequency of the fourth formant (F4). Mean flow and F2 frequency differences were sex and pitch related. Males adjusted laryngeal configuration to produce supported voice, whereas glottal configuration differences were greater in females. Breathing patterns were variable and not significantly different between supported and unsupported voice. Subjects in this study believe that the supported singing voice is resonant, clear, and easy to manage and is produced by correct breath management. Results of data analysis show that the supported singing voice has different spectral characteristics from and higher SPL, peak airflow, and Ps than the unsupported voice. Singers adjust laryngeal and/or glottal configuration to account for these changes, but no significant differences in breathing activity were found.

Effect of enhanced supramaximal flows on cough clearance

Efficiency of cough for clearing mucus from the lungs is believed to be a function of peak airflow velocities in the airways. Initial transient supramaximal flows are characteristic of cough, and these peak flow rates can be enhanced by placing a triggered shutter at the mouth, serving the role of the epiglottis. Using radiolabeled monodispersed aerosols (99mTc-iron oxide) and gamma camera analysis, we measured over a 2-h period the efficacy of 60 voluntary vs. shutter coughs for clearing mucus from the airways of patients (n = 15) with chronic airway obstruction (mean ratio of forced expired volume in 1 s to forced vital capacity = 0.55). In a subset of patients (n = 9), we also measured the efficacy of forced expirations, or huffs, without glottis closure. Peak flow rate was greater for shutter than voluntary coughs [9.4 +/- 2.0 (SD) vs. 4.1 +/- 1.9 l/s; P < 0.001]. Retention at 60 min (as a fraction of initial deposition) was significantly different for the 3 study days (control, 0.83 +/- 0.17; voluntary cough, 0.69 +/- 0.18; shutter cough, 0.75 +/- 0.19; P = 0.01), but only control vs. voluntary cough values were significantly different from each other (P = 0.01). In contrast, retention at 120 min was significantly different for the 3 days, but both voluntary and shutter coughs were significantly different from control (P = 0.01 and P = 0.02, respectively) (control, 0.73 +/- 0.16; voluntary cough, 0.61 +/- 0.20; shutter cough, 0.65 +/- 0.20). Patients studied with buffs showed a clearance rate faster than control and similar to that associated with voluntary cough.(ABSTRACT TRUNCATED AT 250 WORDS)

Composting Process Design Computer Model

A user-friendly computer package, COMPOST, was developed as a design, management, and educational tool to assess composting system requirements. The user enters ingredient characteristics along with critical operational parameters. Output includes the quantity of amendment required to supply the energy needed, the quantity of recycled compost required to adjust the initial moisture content, the mixture moisture content, and the carbon-to-nitrogen ratio of the mixture. The volume required for active composting and curing is calculated along with air flow rates for oxygen supply, moisture removal, and temperature control. The calculations in COMPOST are based on the assumption of a continuous, completely mixed system where ingredients are continuously added and product is continuously removed. However, calculations for mixtures of residue, amendment, and recycled compost and water also apply to batch systems. Peak air flow is calculated to reflect the requirement for a batch system.

Use of flow-volume loops to evaluate upper airway obstruction in exercising Standardbreds

Summary Flow-volume loops generated from 6 Standardbreds at rest and during treadmill exercise were evaluated for their use in detecting upper airway obstruction. Tidal breathing flow-volume loops (tbfvl) were obtained from horses at rest and exercising at speeds corresponding to 75% of maximal heart rate and at maximal heart rate. The tbfvl were evaluated, using a pulmonary function computer; calculated indices describing airflow rate and expiratory-to-inspiratory airflow ratio for individual loops were determined. In addition to tbfvl indices, standard variables of upper airway function also were measured: peak airflow, peak pressure, and calculated inspiratory and expiratory impedances. Measurements were recorded before left recurrent laryngeal neurectomy (lrln; baseline) and 14 days after surgically induced left laryngeal hemiplegia. When horses were at rest, tbfvl shape and indices describing the loop were highly variable. In contrast, in exercising horses, tbfvl shape was consistent and coefficients of variation of loop indices were less during exercise than at rest. After lrln, tbfvl from exercising horses indicated marked inspiratory airflow limitation, while the expiratory airflow curve was preserved. Peak inspiratory flow rate and inspiratory flow at 50 and 25% of tidal volume decreased, and the ratio of peak expiratory to inspiratory airflow and that of midtidal volume expiratory and inspiratory airflow rates increased significantly (P &lt; 0.05). Inspiratory impedance also increased after lrln. Although in resting horses tbfvl were not a useful indicator of upper airway obstruction, examination of tbfvl from exercising horses allowed objective, specific, and repeatable detection of upper airway obstruction. The technique was noninvasive, rapid, and well tolerated by horses; thus, it is a potentially valuable clinical diagnostic test.

Effets de la prise aiguë d'alcool sur la fonction des voies aériennes supérieures

Acute alcohol intake may be of potential hazard in anaesthesia emergency procedures because of consciousness alterations. Alcohol ingestion alters indeed the functions of upper airway muscles and increases the risk of obstructive sleep apnea. However, no data are available on the effects of alcohol on the swallowing reflex (SR), which is a major protective mechanism against pulmonary inhalation and on upper airway resistances (UAR) following external inspiratory load application. This study was designed to investigate the effects of acute alcohol intake on SR and UAR in healthy volunteers. After informed consent, 8 male volunteers (29 ± 3 years) were studied in the supine position. The tip of a catheter was placed through the naris at the epipharynx level for injection of 3 series of 2 volumes of distilled water (0.25 and 1 ml respectively). Swallows were identified by a submental electromyogram. SR efficiency was assessed by recording 1) the latency (L) between injection and the first swallow, and 2) the number of swallows (N) elicited by each bolus. The subjects were breathing through a facial mask connected to a pneumotachograph. Supraglottic airway pressures (UAP) were recorded using a small balloon catheter placed at the tip of the epiglottis. UAR were calculated as the ration of UAP (cmH 2O) on air-flow (l · s −1) at the airflow's peak. After a control set of measurements (TC), including SR assessment and UAR at rest (UARo) and during application of an external inspiratory resistive load (12 cmH 2O · l −1 · s −1) (UARr) to sensitize the experiment, the subjects ingested 1 ml · kg −1 of alcohol as 40° vodka. Measurements were repeated and alcohol blood concentrations assessed 25 (T25) and 45 (T45) min after intake. Statistical analysis were performed using the Kruskal Wallis non parametric test. All subjects were drowsy at T25 and T45 with alcohol blood concentrations of respectively 0.96 ± 0.12 and 1.01 ± 0.15 g · l −1 (mean ± SEM). Although all demonstrated consciousness alterations after acute alcohol intake, no changes in the SR, UARo and UARr occurred. However, these data obtained in young and healthy volunteers can be extended neither to patients receiving sedative agents or opioids nor to elderly as UAR are closely related to age, nor to patients with higher alcohol blood concentrations.

Alpha-adrenergic bronchoprovocation in neonates with bronchopulmonary dysplasia

Ophthalmic administration of phenylephrine caused decreased pulmonary compliance, tidal volume, and peak airflow values in infants with bronchopulmonary dysplasia but not in control infants. The alpha-adrenergic effects of phenylephrine may aggravate the bronchospastic component of bronchopulmonary dysplasia.

The Peak Flow Nasal Patency Index

The peak flow nasal patency index (NPI) is the ratio between the nasal and oral peak airflow. This index was found to be a good indicator of nasal patency present in 24 patients following septoplasty and indicated significant improvement postoperatively. The peak flow nasal patency index was also correlated to self-assessment scores of nasal function in each patient. In this latter study, a low index correlated to a high self-assessment score, both of which indicated poor nasal patency. Our studies have shown that the peak flow nasal patency index is a useful measure for determining nasal patency, particularly for defining the results of any applied therapies.

Vocal intensity in speakers and singers.

Vocal intensity is studied as a function of fundamental frequency and lung pressure. A combination analytical–empirical model is used to predict sound-pressure levels from five professional tensors and twenty-five normal control subjects. The empirical model describes features of the glottal flow waveform (peak flow, peak flow derivative, open quotient, and speed quotient) in terms of lung pressure and phonationthresholdpressure, a key variable that incorporates the F0 dependence of many of the features of the glottal flow. The analytical model describes the contributions to SPL by the vocal tract. Results show that SPL increases with F0 at a rate of 8–9 dB per octave provided that lung pressure is raised proportional to phonation threshold pressure. SPL also increases at a rate of 8–9 dB per doubling of excesspressureoverthreshold, a new quantity that appears to assume prominence in vocal intensity calculations. For the same excess pressure over threshold, the professional tensors studied produced 10–12 dB greater intensity than the male nonsingers, primarily because their peak airflow was much higher for the same pressures.

Cough intensity in patients with a vocal cord palsy

This study assesses the effect a paralysed cord has on the intensity of coughing. The air flow pattern during coughing of 10 patients with a vocal cord palsy was compared with a control group, using a computerized pneumotachograph system. There was no significant difference in the value of the peak air flow but the time taken to reach the maximum value was prolonged in the vocal cord palsy group. This non-invasive test may aid diagnosis of vocal cord palsies but the laterality of the lesion cannot be predicted from the airflow pattern alone.

Bronchial asthma

Asthma is one of the most common respiratory problems in modern industrialized countries, affecting over 5% of the population. It affects all age groups from infants to senior citizens, and mortality rates from asthma appear to be increasing during the past few years in the United States as well as in other industrialized countries. Asthma tends to occur in families, associated with other allergic disease, and may be induced by a wide variety of environmental antigens, most commonly inhaled allergens such as pollen and dust. Bronchial challenge with a specific allergen results in an early bronchospastic response with a relatively brief duration, and in a significant number of patients there is a late response with onset after 3 to 4 hours, lasting hours to days. This late response is associated with a bronchial hypersensitivity reaction, which is demonstrable by nonspecific challenge testing in the laboratory. During the period of bronchial hyperresponsiveness patients are prone to develop attacks following exposure to a wide variety of "triggers," including cold air, fumes, or cigarette smoke. The current approach to management of patients with asthma emphasizes prevention, with avoidance of specific allergens when possible, and chronic use of anti-inflammatory agents including corticosteroids and cromolyn sodium. The goal is to decrease the bronchial hyperresponsiveness. Management of the acute asthma attack consists of bronchodilator therapy, primarily with inhaled beta-adrenergic agonists, and administration of oral or systemic corticosteroids if the attack is not rapidly relieved. Additional therapeutic agents including theophylline and anticholinergics may be useful in some situations. Response to therapy during the first couple of hours in the emergency room is the most important predictor of the course of the acute attack, and patients who have not responded significantly after 2 hours of maximum therapy are candidates for hospital admission or prolonged emergency room observation. The goal of acute therapy is to wean the patient from intravenous drugs and place him or her on rapidly tapering doses of oral prednisone while initiating a vigorous program of preventive therapy. Follow-up observation, both in the office and in the patient's home, is vital and involves extensive patient education and objective testing of peak airflow. In general, the course of asthma is relatively benign compared with other obstructive airway diseases; however, significant mortality exists, especially in older patients and those with late-onset asthma.

Lobeline‐Induced Hyperpnea in Equids

In order to facilitate lung auscultation, a transitory hyperpnea may be obtained by lobeline administration, use of a rebreathing bag or exercise. The effect of these three methods on the pulmonary function were studied and compared in 5 healthy ponies. Respiratory airflow and tidal volume were measured with a pneumotachograph Nr. 5 and pleural pressure with the esophageal balloon catheter technique. Pulmonary function values were measured before, during and after the hyperpnea induced by (i) lobeline, (ii) rebreathing and (iii) exercise. Lobeline administration induced an hyperpnea due to both an increase in tidal volume and respiratory rate; this increase in ventilation lasted for about 90 s and was accompanied by a sharp rise in the respiratory peak airflows, especially the expiratory ones. The rebreathing method induced a less hyperpnea which lasted only 30 s. Lastly the hyperpnea after a light treadmill exercise was the longer in duration and intermediate between the preceding methods in intensity.

Acoustic studies of the voice source in male singers

This paper reviews various recent investigations with various co‐workers of male singers' vocal fold function mainly studied by inverse filtering for deriving the waveform of the transglottal airflow during phonation. Theoretical and experimental studies confirmed the dominating acoustic importance of (1) the peak airflow Ûg for the amplitude of the voice source fundamental, and (2) the negative peak amplitude of the differentiated waveform dU/dt for the SPL of the radiated sound. Unlike nonsingers, some professional baritone and bass singers have been found to retain a high Ûg during loud tones at high pitches. Different strategies are possible for increasing dUg/dt for loudness variation: increasing Ug, increasing the duration of the closed phase, and skewing the pulse shape. Different singers use different combinations of these alternatives depending on pitch, loudness range, and voice type. Some of the physiological correlates of these strategies can be postulated. Here, Ûg seems highly dependent on the degree of glottal adduction and dUg/dt on subglottal pressure. However, influence of the breathing strategy has also been quantitatively demonstrated.

The effect of low density gas breathing on vesicular lung sounds

Turbulent airflow (largely gas density dependent) in larger airways is believed by many lung sound researchers to be teh mechanism responsible for the generation of vesicular lung sounds. To test the validity of this concept, we measured the amplitude of lung and tracheal sounds of 6 subjects alternately breathing air and low density gas mixture (80% helium, 20% oxygen: HeO 2). Lung sounds were recorded from 3 chest wall sites: Anterior right upper lobe (RUL), posterior and posterolateral right lower lobe (RLL), and a site over the proximal trachea below the larynx. The subjects rebreathed into an electronic spirometer filled with the test gas, and achieved a peak inspiratory and expiratory airflow of 2–2.5 L/sec. Lung sound amplitude was determined by an automated, flow-corrected measurement procedure. The mean decrease in sound amplitude when breathing HeO 2 compared to air was: trachea, inspiration 44%; trachea, expiration 45%; RUL, inspiration 13%; RUL, expiration 25%; RLL, inspiration 15% (expiration at the RLL was too quiet to record). Cross-correlation and frequency analyses of teh sounds recorded at the two RLL sites on both test gases revealed no consistent change in frequency or time relationships, indicating absence of effect of gas density on sound transmission between the sound generating airways and chest wall. These data suggest that the mechanism of production of the inspiratory vesicular lung sound is not simply turbulent airflow but some other relatively gas density independent mechanism. The tracheal and expiratory lung sounds do appear to be produced by a more density dependent turbulent mechanism.

Induced transglottal pressure variations during voicing

The effect of variations in the transglottal driving pressure on the glottal air flow waveform is basic to the understanding of the functioning of the laryngeal sound source during speech. A number of laboratories have reported experimentally manipulating the transglottal pressure by mechanically varying the subglottal or supraglottal pressures. If the variations occur in about 100 msec or less it can be assumed that there were no significant compensatory changes in laryngeal or respiratory muscle activity. In this study the supraglottal pressure was varied by having the subject speak into a box having four 15-in. loudspeakers in its walls. The loudspeakers generated variations in supraglottal pressure at preset points in the vocalization. The subject spoke through a circumferentially vented pneumotachograph mask which yielded the glottal air flow waveform after inverse filtering. Reported here are the first attempts at using this apparatus to map out the relationships between transglottal pressure, voice fundamental frequency, peak air flow during the glottal pulse, and glottal pulse width.

The effect of metronome pacing on selected aerodynamic patterns of stuttered speech: Some preliminary observations and interpretations

The purpose of this investigation was to provide some preliminary data regarding the effects of metronome pacing on physiological aspects of speech during stuttering. Five aerodynamic measures were chosen as dependent variables: (a) peak intraoral air pressure, (2) intraoral air pressure onset duration, (3) intraoral air pressure offset duration, (4) total intraoral air pressure duration, and (5) peak air flow rate. Five adult stutterers and five adult nonstutterers read a prose passage containing 12 English consonants, each in three syllable-initial stressed positions, during a control condition and experimental condition. In the experimental condition the subjects read the passage while synchronizing one word per beat at 60 beats per minute. The results demonstrated that both stutterers and normals evidenced lower peak pressures and greater pressure durations during metronome pacing. Air flow rates increased for normal subjects and decreased for stutterers in the experimental condition. Dysfluencies recorded during the control condition were observed to have much more rapid intraoral air pressure onsets when compared with fluent counterparts in the experimental reading. These results were interpreted with reference to Wingate's (1969) modified vocalization hypothesis and Van Riper's (1971) altered timing concept.

Oral Air Pressure and Airflow in German Stop Consonants

Abstract The interaction of peak oral air pressure and peak airflow rate in the production of medial voiceless stop consonants in German is investigated and the claim that the two parameters are linearly related is considered. It was found that the two parameters behave in a similar fashion with respect to the consumption of aerodynamic energy prior to the plosive and to the degree of expiratory activity, but in a reverse fashion with respect to an increase in the rate of speech. The degree of opening of the glottis is thought to be responsible for the reverse behaviour of the parameters in this case.

Airway obstructed by foreign material: The Heimlich maneuver

To investigate the application of a cough-creating thrust for the removal of airway-obstructing foreign material, the thrust was applied to six adult male anesthetized volunteers at the waist, at the low chest level, and at the midchest level, with the subjects in both the horizontal-lateral and the sitting positions. Air volume, peak air flow rate, and airway measurements were made. Both the low chest and midchest thrusts produced significantly better results than did the abdominal thrust. There were no side effects attributable to the thrusts. The ease of application and consistently better level of results indicate that the chest thrust is the technique of choice. The application of the chest thrust should be integrated into the concepts of basic life-support and cardiopulmonary resuscitation.

Respiratory volume and airflow characteristics of speech produced by deaf individuals

Respiratory volume and airflow characteristics associated with oral reading were examined for 12 females with profound hearing losses and 16 females with normal hearing. The deaf's results of respirometric analyses were further correlated with degree of hearing loss, overall speech proficiency, and breathiness. The results indicated that the deaf subjects as a group exhibited different speech breathing patterns in comparison with those of the normal-hearing subjects. The speech respiration of the deaf was characterized by (1) high air consumption manifested as high air expenditure per syllable, high average exhalatory airflow rates, and high peak airflow rates, (2) frequent inspirations, (3) inspirations at linguistically inappropriate places, (4) short duration of exhalation, and (5) sizable within-group variability. These characteristics of the deaf's speech respiration were especially prominent among the most profoundly deaf subjects. Correlational analyses revealed that more frequent breath taking during reading seemed to adversely affect overall speech proficiency while high air consumption was closely related to a breathy voice quality.