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Results 301 - 350 of 1034
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Nakamura Toshiaki - - 2008
In this paper, we describe the characteristics of an acoustic aplanat lens which can eliminate both spherical and coma aberrations. A singlet aplanat lens was designed using a ray theory in paraxial area. Sound pressure fields of the bi-concave aplanat lens and a spherical lens with 160 mm in diameter ...
Cheenne Dominique J - - 2008
Anechoic recordings of balloon bursts were systematically acquired for various conditions of balloon diameters, puncture location, and inflation pressure. The recordings were analyzed to derive the average frequency spectrum over the effective duration of the acoustic impulse. Although the data show the well-known limitations for the impulse responses (in terms ...
Blake William - - 2008
Sound produced by turbulent-boundary layers (TBL) over rough walls is being studied in a series of physical-computational experiments. At issue is the development of a knowledge of how the wall elements generate flow dipoles which directly determines how the sound is described in terms of dependent variables. The considered mechanisms ...
Guedel Alain - - 2008
Broadband noise is a major part of the noise radiated by low-speed fans such as industrial and domestic fans. One of the main mechanisms of broadband noise is blade trailing-edge noise, which is due to the convection of the turbulent flow of the boundary layer past the blade trailing edge. ...
Scherer Ronald C - - 2008
Asymmetric vocal fold oscillation occurs for both normal and pathological phonation. The pressures on the right and left glottal walls receive different pressures when the glottis is oblique, as we have shown previously. Different driving forces may affect the motion, although to what extent is not yet known. We have ...
Czerwonka Lukasz - - 2008
HYPOTHESIS: Vocal fold vibration may physically raise intravascular pressure to levels high enough to damage capillaries and result in leakage of erythrocytes. This type of injury is commonly seen in benign vocal fold lesions and is not well explained. STUDY DESIGN: Theoretical, retrospective. METHODS: The relationship of intravascular pressure to ...
Mellow Tim - - 2008
Radiation characteristics are calculated for a circular planar sound source in free space with a uniform surface pressure distribution, which can be regarded as a freely suspended membrane with zero mass and stiffness. This idealized dipole source is shown to have closed form solutions for its far-field pressure response and ...
Foo Jong Yong A - - 2008
OBJECTIVES: Vascular transit time (VTT) can be defined as the first heart sound of the phonocardiography (PCG) signal to its arrival at the photoplethysmography (PPG). Studies have shown that monitoring VTT can be useful as an early prognosis of cardiac diseases. However, there is limited study conducted to understand the ...
Ahlstrom C - - 2008
We have previously developed a method for localization of the first heart sound (S1) using wavelet denoising and ECG-gated peak-picking. In this study, an additional enhancement step based on cross-correlation and ECG-gated ensemble averaging (EA) is presented. The main objective of the improved method was to localize S1 with very ...
Tao Chao - - 2008
The effect of the pressure recovery at glottal exit is introduced to modify the one-mass model. Using the modified one-mass model, the phonation critical condition, including phonation threshold pressure and phonation threshold flow, is analyzed by using the small-amplitude oscillation theory. It is found that the phonation threshold pressure is ...
McNamar Justin - - 2008
HYPOTHESIS: Adduction arytenopexy (AP) with thyroplasty provides improved physiologic placement of the vocal fold and therefore provides improved acoustic, aerodynamic, and vibratory function as compared with arytenoid adduction (AA) with thyroplasty. METHODS: Five cadaveric human larynges were prepared by removing supraglottic tissues and fixing the nontest vocal fold medially on ...
Tsiou Chrisoula - - 2008
This study is an evaluation of the problem of noise pollution in operating rooms. The high sound pressure level of noise in the operating theatre has a negative impact on communication between operating room personnel. The research took place at nine Greek public hospitals with more than 400 beds. The ...
Koenig Laura L - - 2008
Previous authors have established that stop consonant voicing is more limited in young children than adults, and have ascribed this to immature vocal-tract pressure management. Physical development relevant to speech aerodynamics continues into adolescence, suggesting that consonant voicing development may also persist into the school-age years. This study explored the ...
Decremps F - - 2008
We report an innovative high pressure method combining the diamond anvil cell device with the technique of picosecond ultrasonics. Such an approach allows us to measure sound velocity and attenuation of solids and liquids under pressure of tens of GPa, overcoming all the drawbacks of traditional techniques. The power of ...
Koenig Laura L - - 2008
The aim of this within-speaker case study was to explore how effectively a phonetically trained speaker could alter the likelihood of voicing around abduction, and what changes he made to do so. An American English-speaking male produced intervocalic /h/ in varying loudness and vowel contexts. When given no specific instructions ...
Choi Hyun-Seok - - 2008
In this paper, a new noise reduction method was proposed for oscillometric blood pressure measurement. The proposed method uses a capacitive sensor and an adaptive filter to minimize blood pressure measurement error. Noise such as undesired external pressure applied to cuff was focused on. Three types of the distorted oscillation ...
Carter Calvin - - 2008
Binaural beats are the differences in two different frequencies (in the range of 30-1000 Hz). Binaural beats are played through headphones and are perceived by the superior olivary nucleus of each hemisphere of the brain. The brain perceives the binaural beat and resonates to its frequency (frequency following response). Once ...
Harvey Margaret B - - 2008
T wave alternans (TWA) is a marker of ventricular electrical instability considered to be predictive for ventricular tachyarrhythmias. Techniques have been developed to detect TWA at the microv level as a method for arrhythmia risk stratification of persons at high risk for sudden cardiac death. Currently, TWA is typically calculated ...
Plummer Emily Megan - - 2008
Song of the zebra finch (Taeniopygia guttata) is a complex temporal sequence generated by a drastic change to the regular oscillations of the normal respiratory pattern. It is not known how respiratory functions, such as supply of air volume and gas exchange, are controlled during song. To understand the integration ...
Bombardini Tonino - - 2008
Recently, a cutaneous force-frequency relation recording system based on first heart sound amplitude vibrations has been validated. A further application is the assessment of Second Heart Sound (S2) amplitude variations at increasing heart rates. The aim of this study was to assess the relationship between second heart sound amplitude variations ...
Alipour Fariborz - - 2009
This study was to investigate glottal flow resistance in excised pig, sheep, and cow larynges during phonation at different oscillation ranges and to examine the relation of the glottal flow resistance to the laryngeal geometry and vocal fold vibration. Several pig, sheep, and cow larynges were prepared, mounted on an ...
Kieser Jules - - 2008
This article introduces a new way of recording intraoral pressures from a range of locations within the oral cavity. To measure pressure flow dynamics during swallowing, we fitted eight miniature pressure transducers capable of measuring absolute pressures to a chrome-cobalt palatal appliance with a labial bow. Unlike previous devices, our ...
Lawrenson Christopher C - - 2007
A condenser microphone has been fabricated for measuring low-frequency sound pressure. The goal of this design is to keep the background noise as low as possible. The microphone features a high membrane compliance with a large backchamber volume, a prepolarized backplane, and a high impedance preamplifier located inside the backchamber. ...
Toussaint Edward L - - 2007
Western free reed instruments, including the reed organ, harmonium, harmonica, and accordion, use asymmetric free reeds that are able to maintain sustained oscillation in the absence of a pipe resonator. Studies of the motion of air-driven American reed organ reeds and accordion reeds have been made that yield the volume ...
Hastings Mardi C - - 2007
Several studies [A. R. Scholik and H. Y. Yan, Hear. Res. 152, 17-24 (2001); A. N. Popper et al., J. Acoust. Soc. Am. 117, 3958-3971 (2005); M. E. Smith et al., J. Exp. Biol. 209, 4193-4202 (2006)] indicate that the equal energy hypothesis does not apply when evaluating auditory effects ...
Ahroon William A - - 2007
An earlier presentation described a hybrid instrument using electromechanical and ultrasound-Doppler techniques to permit auscultation in extremely noisy environments, such as Army medical evacuation vehicles [Houtsma et al., J. Acoust. Soc. Am. 120, 3361 (2006)]. That paper presented the theories behind the hybrid instrument and provided simulations of auscultation in ...
Tessien Ross A - - 2007
The behavior of shocks emitted from transient cavitation in acoustic cavitation systems with static pressures up to 300 bar is explored using photomultiplier tubes, hydrophones, Schlieren, and Shadowgraphic methods. Shocks emitted from strong implosions travel initially at supersonic velocities, leading to a shortening of the time of flight (TOF) from ...
Lau C K - - 2007
The vortex dynamics and the sound generation by an inviscid vortex in the presence of a finite length porous material on an otherwise rigid plane are studied numerically in the present study in an attempt to understand the sound generation near the surface of a wall lining in a lined ...
Raspet Richard - - 2007
Recent research on the prediction of wind noise contributions from the measured turbulent velocity spectrum has led to a better understanding of what meteorological variables are necessary to analyze and compare wind noise measurements on infrasound arrays. In this talk, we will describe the variables necessary to correlate different contributions ...
Peak Chris - - 2007
Sound power and dynamic pressure measurements were used to identify where noise is generated by a single spindle lawnmower deck. The sound power measurements were performed with different blades and deck profiles to quantify the overall levels. An electric motor was used to turn the blade, and the measurements were ...
Gabrielson Thomas B - - 2007
There are several commercial measurement-grade condenser microphones that are suitable for measurements down to about 0.1 Hz; however, these one-half-inch microphones reach those low frequencies with an in-line attenuator that compromises the overall dynamic range. In a previous paper [T. M. Marston and T. B. Gabrielson, J. Acoust. Soc. Am. ...
Rasmussen Gunnar - - 2007
Infrasonic measurements and calibration. Infrasonic measurements call for special instrumentation in order to cover the low frequency range. Below 100 Hz the microphones present a special problem. The microphone performance is very different between free field conditions with wave motion and closed conditions without propagating waves. The primary method for ...
Yanagisawa K - - 2007
The purpose of this study was to clarify which physiological and anatomical factors were involved in the formation of tongue indentations, which are believed to be a clinical sign of clenching. Twenty-four dentulous subjects were investigated. They were divided into two groups, depending on the presence or absence of tongue ...
Hedwig Gavin R - - 2008
Sound speeds have been measured for aqueous solutions of alanine and the peptides alanylglycine (alagly), alanylglycylglycine (ala(gly)(2)), alanylglycylglycylglycine (ala(gly)(3)) and alanylglycylglycylglycylglycine (ala(gly)(4)) at T=298.15 K and at the pressures p=0.1, 5.0, 10.0, 20.0, 40.0, 60.0, 80.0 and 100.0 MPa. A method is described whereby reliable partial molar volumes at infinite ...
Alipour Fariborz - - 2007
The purpose of this study was to find relationships between subglottal pressure (P(s)) and fundamental frequency (F(0)) of phonation in excised larynx models. This included also the relation between F(0) and its rate of change with pressure (dFdP). Canine larynges were prepared and mounted over a tapered tube that supplied ...
Voss Susan E - - 2007
Direct acoustic stimulation of the cochlea by the sound-pressure difference between the oval and round windows (called the "acoustic route") has been thought to contribute to hearing in some pathological conditions, along with the normally dominant "ossicular route." To determine the efficacy of this acoustic route and its constituent mechanisms ...
Bovenzi Massimo - - 2008
OBJECTIVES: To investigate prospectively the relation between vibration-induced white finger (VWF), exposure to hand-transmitted vibration (HTV) and the cold response of digital arteries in users of vibrating tools. METHODS: Two-hundred and sixteen HTV workers and 133 control men of the same companies underwent initially a medical examination and a standardised ...
Lu H Z - - 2007
Small axial-flow fans used for computer cooling and many other appliances feature a rotor driven by a downstream motor held by several cylindrical struts. This study focuses on the aerodynamic mechanism of rotor-strut interaction for an isolated fan. The three-dimensional, unsteady flow field is calculated using FLUENT, and the sound ...
Hottinger Daniel G - - 2007
OBJECTIVES/HYPOTHESIS: This experiment studied a new aerodynamic parameter, phonation threshold flow, along with phonation threshold pressure, by varying prephonatory glottal width in canine larynges ex vivo. Goals were to examine phonation threshold flow as a measurable parameter sensitive to physiologic changes in the vocal folds and compare the relative sensitivities ...
Ni Chun-hui - - 2007
BACKGROUND: There are few studies on the arterial compliance of noise exposure. The purpose of this study was to understand the relationship between hearing loss, blood pressure and arterial compliance of female workers who exposed to occupational noise in a textile mill. METHODS: The noise levels in the workplace were ...
Niss K - - 2007
We study the changes in the low-frequency vibrational dynamics of poly(isobutylene) under pressure up to 1.4 GPa, corresponding to a density change of 20%. Combining inelastic neutron, x-ray, and Brillouin light scattering, we analyze the variations in the boson peak, transverse and longitudinal sound velocities, and the Debye level under ...
Baggott Christopher D - - 2007
Subglottal pressure (SGP) is a valuable parameter in the research and clinical assessment of laryngeal function. The lungs serve as a constant pressure source during sustained phonation, and that pressure, SGP, can be used to determine the efficiency with which the larynx converts aerodynamic power to acoustic power. As the ...
Wålinder Robert - - 2007
OBJECTIVES: This study tested the hypothesis that classroom noise is related to stress reactions among primary school children. Stress was monitored via symptoms of fatigue and headache, systolic blood pressure, reduced diurnal cortisol variation, and indicators of emotional distress. METHODS: In three classrooms of pupils in the fourth grade (10 ...
Mahajan Aman - - 2007
BACKGROUND: Auscultation of breath sounds is used routinely to confirm tracheal placement of endotracheal tubes (ETT). In infants and children, this method is limited by the conduction of breath sounds bilaterally, despite endobronchial intubation. Although several methods of detecting endobronchial intubation have been described, none is both simple and reliable. ...
Tack Johannes W - - 2007
BACKGROUND: A sound generator based on a double-membrane design that fits into a regular tracheoesophageal shunt valve may improve voice quality after total laryngectomy in patients rehabilitated with surgical voice prostheses. METHODS: Voice-producing element (VPE) prototypes were manufactured using medical grade biocompatible materials and tested in vitro under physiological conditions. ...
Takahashi Hirokazu - - 2008
In normal speech, coordinated activities of intrinsic laryngeal muscles suspend a glottal sound at utterance of voiceless consonants, automatically realizing a voicing control. In electrolaryngeal speech, however, the lack of voicing control is one of the causes of unclear voice, voiceless consonants tending to be misheard as the corresponding voiced ...
Hart Roger C - - 2007
Nonintrusive, off-body flow barometry in Mach 2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, the ...
Cobo Pedro - - 2007
Although hybrid passive-active absorption in impedance tubes has been widely analyzed, its study in more realistic conditions remains to be accomplished. This letter describes the practical measurement of the passive-active absorption coefficient in a free field. The passive absorber consists of a microperforated panel backed by an air cavity and ...
Zhang Yu - - 2007
PURPOSE: The present study was a methodological study designed to reveal the dynamic mechanisms of phonation instability pressure (PIP) using bifurcation analysis. Phonation pressure range (PPR) was also proposed for assessing the pressure range of normal vocal fold vibrations. METHOD: The authors first introduced the concept of bifurcation on the ...
Laukkanen Anne-Maria - - 2008
This study investigated the peak-to-peak (p-t-p) amplitude of the voice source as a function of fundamental frequency (F(0)). Nine males and nine females with or without singing training produced (1) a glissando from lowest to highest F(0) and back in their speaking range on /a:/ and (2) an ascending-descending scale ...
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