Maximum Sound Pressure Level Research Articles

Changes in Speech Range Profile Are Associated with Cognitive Impairment

Background and PurposeThe aim of this study was to describe the variations in the speech range profile (SRP) of patients affected by cognitive decline.MethodsWe collected the data of patients managed for suspected voice and speech disorders, and suspected cognitive impairment. Patients underwent an Ear Nose and Throat evaluation and Mini-Mental State Examination (MMSE). To obtain SRP, we asked the patients to read 18 sentences twice, at their most comfortable pitch and loudness as they would do in daily conversation, and recorded their voice on to computer software.ResultsThe study included 61 patients. The relationship between the MMSE score and SRP parameters was established. Increased severity of the MMSE score resulted in a statistically significant reduction in the average values of the semitones to the phonetogram, and the medium and maximum sound pressure levels (p<0.001). The maximum predictivity of MMSE was based on the highly significant values of semitones (p<0.001) and the maximum sound pressure levels (p=0.010).ConclusionsThe differences in SRP between the various groups were analyzed. Specifically, the SRP value decreased with increasing severity of cognitive decline. SRP was useful in highlighting the relationship between all cognitive declines tested and speech.

Modelling of underwater noise emissions by ships in Klaipėda Strait, Lithuania

One of the United Nations Sustainable Development Goals regarding “conservation and sustainable use of the oceans, seas, and marine resources” emphasizes the urgency of eliminating harmful effects on the sea and its biota, where the role of anthropogenic activities is crucial. The global trend of merchant shipping is increasing, thus enlarging underwater noise levels. As a result, greater noise can harm aquatic animals in their habitats. In the Baltic Sea, the underwater sound pressure levels are now being evaluated utilizing noise measurement, modelling, and mapping. In areas such as narrow ship passages, namely lagoons, channels, or straits, the ambient underwater noise modelling becomes very complex, even though these EU inland waters are regarded by legislation as part of the marine basin. For instance, the Klaipėda Channel (Klaipėda Strait), connecting the Baltic Sea and the Curonian Lagoon, is regarded by the national Lithuanian legislation as part of marine waters, where the environmental status should be evaluated according to the EU Maritime Strategy Framework Directive. In this narrow channel, an alternative to the modelling of ambient sound pressure levels can be applied to understand the long-term trends of vessel-sourced noise emissions. In this paper, an example of application of ship noise emission modelling for a narrow Klaipėda Harbour area is presented, along with the results obtained throughout 2015–2017. The modelled noise levels in the harbour area reached the median levels of 112.5 dB in 2015 and 102.6 dB re 1 µPa2 in 2017. The maximum emitted instantaneous sound pressure levels by ships reached 173.7 dB in 2015 and 179.4 dB re 1 µPa2 in 2017 in the area of interest.

Modelling and optimization of PVDF based surface acoustic wave MEMS microphone

A detailed finite element simulations of a piezoelectric based biomimetic surface acoustic wave device as MEMS Microphone is analyzed. A symmetric piezoelectric PVDF based MEMS Microphone inspired by Ormia Orchea provides an excellent frequency response for four resonant frequency bands 84.051 K Hz, 134.25 K Hz, 134.4 K Hz and 137.8 K Hz. The device is actuated in two different modes, bending and rocking mode and its sound pressure field and absolute pressure is analyzed for its structural properties. The signal mapping and transduction method for the MEMS microphone is achieved by incorporating four Inter Digited Electrodes along the wings of the biomimetic structure stacked on piezoelectric membrane guiding the surface acoustic waves along the membrane. The maximum sound pressure level of 381.2 dB is attained at 820 µm at the center of the membrane and a spatial distribution of surface pressure to a value of 4.31 × 10−11 Pa for 84.041 KHz. The design with its functionality is apt for fabrication with the stacked nanomaterials.

Experiment on aeroacoustic characteristics of a NACA0012 airfoil with rime ice model on the leading edge

Ice accretion changes the shape of the airplane aerodynamic surface, resulting in not only the degradation of aerodynamic performance but also the variation of the aeroacoustic characteristics. In order to explore the effect of the ice accretion on the aerodynamic noise, a NACA0012 airfoil with rime ice model on the leading edge was investigated experimentally in an aeroacoustic wind tunnel using far-field microphone array measurements. Two rime ice models of different ice thickness were attached on the airfoil leading edge. The results were compared with the baseline airfoil at various airflow speeds and different angles of attack. The experiments reveal that the ice model increases the maximum far-field sound pressure level (SPL) by 9.5 dB in the frequency band of 7–25 kHz. And the averaged OASPL difference between airfoil with ice model and baseline airfoil is linear with the 1/2 power of ice thickness. Higher angle of attack results in larger increase of the noise level. Steady RANS simulation as well as large eddy simulation was also performed to uncover the mechanism of the noise increase by the rime ice model. The presence of the rime ice model altered the local flow field around the leading edge of airfoil, resulting in the variation of airfoil surface pressure fluctuation and far-field acoustic characteristics. It would enhance the noise radiation of the airfoil, which was verified by the sound power level (PWL) of airfoil with ice model. It may provide an idea to develop a novel ice detection method based on the far-field noise increment by the ice model.

Influence of pontic design on speech with an anterior fixed dental prosthesis: A clinical study and finite element analysis

Statement of problemPatients may experience disturbed articulation after treatment with a fixed dental prosthesis. However, studies that assess the relationship between fixed dental prosthesis design and the accuracy of speech sound production are lacking. PurposeThe purpose of this clinical and finite element analysis (FEA) study was to examine the influence of pontic design on speech with anterior fixed dental prostheses. Material and methodsFirst, an articulation test was carried out in which a partially edentulous participant was required to pronounce 4 Chinese words containing the voiceless fricative/s/while wearing fixed dental prostheses with 2 types of pontic designs. The oral morphology was obtained by cone beam computed tomography (CBCT) scanning while the participant, wearing the 2 fixed dental prosthesis designs, was pronouncing the voiceless fricative/s/sound. The geometry of the oral cavity was then reconstructed by an image processing software program. Finally, a finite element model for sound wave propagation inside the oral cavity was developed within the framework of the finite element analysis software program. By using this model, the sound pressure level of the 2 types of pontic design was characterized and quantified under different fundamental frequencies (F0). The data were analyzed with 1-way ANOVA (α=.05). ResultsThe experimental articulation test reported that the pontic design of fixed dental prostheses affected the speech production of the/s/sound (P<.001). The numerical study reported that the sound pressure level values were different under various fundamental frequencies. In addition, the pontic design of fixed dental prostheses affected the sound pressure level values, and the differences varied significantly from 420 to 1300 Hz (P<.05); however, the differences were not significant between 120 and 420 Hz (P>.05). Moreover, further comparisons of low F0 (120 to 500 Hz), medium F0 (520 to 900 Hz), and high F0 (920 to 1300 Hz) reported that the differences in the medium F0 area were most obvious (P<.001 for maximum sound pressure level value and P=.001 for sound pressure level value at Point Q). ConclusionsBoth the fixed dental prosthesis pontic design and the fundamental frequency could affect the sound field distribution.

Analysis and hygienic evaluation of noise burden in public education organizations in Saransk

Background . Noise pollution is a burden exerting a harmful and irritating effect on human health. Children are particularly sensitive to noise burden. In this connection, it is especially important to control the noise pollution level in public education organizations where children spend significant time. Objective . The study is aimed at determining objective and subjective parameters of noise pollution in public education organizations based on the analysis of data obtained by measuring noise levels in school campuses in Saransk and directly in classrooms, as well as by questioning the teachers of these schools. Methods . The measurement of noise burden was carried out in 10 schools using the noise and vibration level meter “Assistant” with class I accuracy. Noise measurements in school campuses and classrooms were performed in accordance with the GOST 23337-2014 requirements. Assessment of results was conducted in accordance with sanitary standards 2.2.4/2.1.8.562-96 “Noise in the workplace, residential and public buildings and housing developments”. Results . Based on noise measurement results, the highest noise levels were found in school № 2 (65.5 dBА on the campus, 51.2 dBA in the classroom) which is located in the center of a traffic interchange. The lowest noise parameters were found in school № 35 (45.2 dBА on the campus, 37.7 dBА in the classroom) which is located in the residential quarter quite far away (242-321 m) from the main source of noise, the motorway. Conclusion . Study results attest that maximum noise levels at school campuses do not exceed the permissible exposure limit of 70 dBA. In all schools noise values conform to the noise standards (maximum sound pressure level in classrooms did not exceed 55 dBA).

Numerical investigation of geometrical parameters on the hydrodynamic noise characteristics of submerged bodies and comparisons with experiments

The effects of the geometrical parameters on the hydroacoustic characteristics of the flow over rectangular, square and circular cylinders are investigated by numerical analyses and experiments. The numerical simulations are carried out by using a hybrid method which combines RANS with FWH equation. In order to validate the numerical results, the hydroacoustic measurements are also performed for the circular cylinders. The circular cylinders with diameters of 9.5, 19.0, 38.0 and 65.0 mm and aspect ratios of 2.5, 5.0 and 10.0 are employed for the hydroacoustic measurements and analyses. The rectangular cylinders with side ratios of 0.3, 0.6, 1.8 and 3.0, and also square cylinder with the side ratio of 1.0 are considered in hydroacoustic analyses. The Reynolds numbers are in the range of 2.25 × 104 and 1.7 × 105. The hydroacoustic characteristics of the cylinders are obtained to be completely different due to the differences in the shear layer separation, reattachment mechanism and the intensity of disturbance. The shape of the noise spectrum significantly changes with the geometrical shapes of the cylinders. The spectrum becomes narrower by an increase in the side ratio. The main peak frequency reduces when the side ratio increases. The highest value of the maximum sound pressure level, SPLmax are observed for the square cylinder and the lowest value for the rectangular cylinder with the side ratio of 0.6. The peak spectrum becomes like a line spectrum as the cylinder diameter decreases. The main peak frequency decreases when the cylinder diameter increases but it is almost constant with the aspect ratio. At the constant Reynolds number, the broadband noise level and SPLmax decrease with an increase in the cylinder diameter and decrease in the aspect ratio. A good agreement between the numerical and experimental results are obtained.

Numerical study on magneto-acoustic thermal characteristics of micro-speaker for mobile phones

The numerical study was conducted on 1.2 W micro-speaker module of yoke thickness 0.40 mm without center air hole used in mobile phones and experimentally validated for sound pressure level and temperature distribution within ± 5.9% and ± 3.6%, respectively for frequency ranging from 100 Hz to 20 kHz. The sound pressure level, magnetic flux density, magnetic excitation force and temperature distribution of three different micro-speaker designs were evaluated. The micro-speaker module design with yoke thickness of 0.45 mm without center air hole showed superior acoustic, magnetic and thermal performance as compared to other module designs with the lowest voice coil temperature of 126.02 °C and the maximum sound pressure level of 118.6 dB around resonant frequency of 1100 Hz. The proposed nonlinear thermal model predicted the voice coil temperature accurately. In addition, the present study demonstrated the complete 3-dimensional thermal distribution of micro-speaker components and the detailed heat flow pattern.

Numerical simulation on near-field aerodynamic noise of an adjustable-blade axial-flow fan

A numerical simulation method based on the Ffowcs-Williams and Hawkings model is employed to predict the mechanisms of the near-field aerodynamic noise distribution characteristics of an adjustable-blade axial-flow fan with different installation angles of moving blades (Δβ). The simulated results reveal that with Δβ changing from −12° to 12°, the changing curves of the maximum total sound pressure level (MTSPL) at the tip clearance region (A region), the leading edge region (B region), and the trailing edge region (C region) exhibit an apparently rising trend, which increase by 4.0 dB, 5.7 dB, and 4.3 dB, respectively. Besides, the MTSPL at the C region is always smaller than that at A and B regions within the studied installation angles. Additionally, the acoustic energy ratio (Cpi) is the ratio of the sound energy density of a certain frequency to the total sound energy density, which shows the various frequency distribution characteristics under studied angles. It is found that when Δβ deflects from −12° to 0°, Cp1 (the acoustic energy ratio at the low-frequency in the range of 20–500) decreases from 0.71 to 0.59, Cp2 (the acoustic energy ratio at the intermediate-frequency in the range of 500–2000) increases from 0.18 to 0.25, and Cp3 (the acoustic energy ratio at the high-frequency in the range of 2000–3000) rises from 0.1 to 0.16. This study derives the aerodynamic distribution characteristics of the TSPL and acoustic energy in the near field of moving blades, which reveals its changing rules and frequency distribution under various installation angles. The conclusions may provide guidance for the research regarding the technology of the noise control of the adjustable-blade axial-flow fan.

Aerodynamic noise characteristics of the flow past a circular cylinder

The present study experimentally investigates the aerodynamic noise from the flow past a fixed circular cylinder. The cylinders considered for the study have the diameters (d) in the range of 6 to 25 mm while its span length (L) is constant, which is 300 mm. The free stream velocity is varied up to 50 m/s, and the corresponding Reynolds number (based on d) varies up to 8.3 104, thus maintaining the flow past the cylinder in the subcritical regime. The discrete narrowband frequency tones depicting the aeolian tones are noted in the spectra. The results showed that the aeolian tone frequency decreases with an increase in the cylinder diameter and ceases to exist beyond the diameter of 15 mm. The corresponding Strouhal number of these tones is found to be in the range of 0.18 to 0.21, which is in congruence with the vortex shedding frequency in the subcritical regime. The maximum overall sound pressure level for cylinders having tonal noise is higher by around 30 dB compared to the background noise. Directivity studies show that the noise level is higher along the perpendicular direction of the jet flow. A sixth power Mach number scaling of the acoustic spectra shows a good collapse of the acoustic tonal amplitude.

FEM simulations of acoustic wave propagation in the vicinity of the railroad structure

Noise is one of the major environmental concerns nowadays. The problem is especially significant around large urban agglomerations where high levels of noise can have a negative impact on physical or psychological well-being of citizens while a long-term exposure can be harmful to health. Residential areas are protected by the introduction of maximum allowable sound pressure levels according to appropriate norms. There are also similar regulations concerning natural areas under environmental protection. Different measures used in order to reduce levels of noise should be applied primarily to the source of the sound. This is the task mainly for the manufacturers of all kinds of machines as well as means of transport. However, noise levels can be also controlled by the introduction of appropriately designed or chosen elements or materials in civil engineering structures. The noise levels emitted by the rail traffic depend on the number, kind and speed of trains, night and day traffic organization as well as on the type of the railroad structure and its location (e.g. on an embankment, on a bridge or flyover). Railway noise mainly develops between wheels and rails and depends on the roughness of both these elements, rolling speed and dynamic characteristics of the railroad. The paper presents the mathematical formulation of a coupled acoustic-structure problem. Solving the problem with finite element method gives the possibility to predict sound pressure levels in the vicinity of a railway structure. A numerical model of a certain type of a railroad structure was built in order to simulate the acoustic wave propagation caused by a wheel-rail interaction. The harmonic analysis was carried out using the Abaqus software. The acoustic pressureobtained based on the harmonic analysis was evaluated in certain points of the acoustic medium for various excitation frequencies. The final results were presented in the form of one-third octave bands. In the article, a possible methodology for estimating noise levels from railway structures based on a numerical analysis was shown. In the future works, the numerical model will be validated by field test data and applied to evaluate different types of technological solutions (silencers) used to reduce railway noise levels. This paper is part of the project “Innovative solutions for the protection of people and building against noise from rail traffic”. The project is co-financed by the European Union from the European Regional Development Fund within the framework of the Smart Growth Operational Programme and by PKP PLK S.A. within the framework of a joint venture BRIK. Keywords: Finite Element Method; Acoustics; Railway Noise

Acoustic analysis of a single-cylinder diesel engine using magnetized biodiesel-diesel fuel blends

Fuels have important effects on the quality parameters of engines such as noise pollution and vibration. Diesel fuel are used in wide range of applications especially in compression ignition engines. The objective of the present research is evaluation of the noise emitted from a single-cylinder diesel engine using magnetized biodiesel-diesel fuel blends. In general, samples were provided with different percentages of the biodiesel-diesel blends as diesel (100, 95, 90, and 80%) and biodiesel (0, 5, 10, and 20%) by applying magnetic field (0, 5300 and 7000 G) to fuel line known as DxByMz. The measurements were done on a power tiller engine at a 10 cm distance from driver ear with three replications. The statistical approach in time domain and signal processing in frequency domain were applied for data analysis. The results of the variance analysis approved significant differences between the studied fuel blends and magnetic levels at 1% probability level. The highest and lowest average value of sound pressure level was corresponded to D100B0M0 and D80B20M5300, respectively. The results in frequency domain showed that the maximum sound pressure level values were in the frequency range of 31.5–200 Hz for all fuel blends and magnetic levels. The frequencies related to the maximum sound values varied by changing biodiesel percent and magnetic level.

In-situ Noise Measurement and Analysis for the Motorcycle Muffler

Noise from the vehicles is one of the noise pollution to the environment. The noises emitted by the vehicles have to obey the requirement of regulation of maximum sound pressure level permitted for respective vehicles. In this study, the aim is to reduce the noise emitted from the motorcycle muffler. The noise emitted from the motorcycle muffler is analyzed and measured using a sound level meter. The average sound pressure level of the motorcycle muffler is determined in certain conditions. The sound pressure level is obtained from original motorcycle muffler, when it is under constant speed (10 km/hr, 20 km/hr, 30 km/hr) and under acceleration (in the scope of 0 km/hr to 30 km/hr). The study is continued by using a modified motorcycle muffler which contains sound absorptive materials. The absorptive materials chosen are glass wool, cotton and Styrofoam and they are taking turn to be placed into the motorcycle muffler to reduce the sound pressure level. Then the experiment is repeated. It is found that Styrofoam does not perform significantly in absorbing sound or noise in this study. Glass wool demonstrates relatively better sound energy absorption compared with cotton. In general, soft and porous materials are considered good performance in sound absorption. Denser materials are better at soundproofing or sound blocking. Therefore, glass wool with relatively higher density among the investigated absorptive materials in this study has the greatest sound absorption performance.

Acoustic characteristics of water-jet propulsion with screw mixed-flow pump under quasi-submerged state

As a key point of the stealth performance, acoustic characteristics of a screw mixed water-jet pump were investigated under the quasi-submerged state. The relationships between thrust and rotation speed of screw-mixed pump, drag, and submerged velocity of water-jet propulsion were obtained from the flume tests and numerical simulation. Based on the results of the unsteady flow field calculation with the detached eddy simulation (DES), the sound radiation fields of the screw mixed water-jet propulsion at different rotation speeds were investigated by the finite element method (FEM) coupled with the vibro-acoustic method. The flow-induced dipole source noise of every flow passage component increases with the increasing of rotation speed. The mathematical relations of the flow-induced noise at impeller between different rotation speeds were established. The maximum sound pressure level (SPL) of every flow passage component appears at the impeller blade-passing frequency (BPF). In the medium-high frequency domain, dipole source induced noise from the impeller is the main external noise field during the propulsion process. At the first-order BPF, the ratio of SPL of the impeller is equal to the 0.5 power of the rotation speed in the phase of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]. At the sixth-order BPF, the ratio of SPL of the impeller is directly proportional to the reciprocal power of rotation speed ratio in the phase of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text].

Effect of Blade Outlet Angle on Acoustics of Marine Centrifugal Pump

To research the effect of blade outlet angle on acoustics of marine centrifugal pump, the unsteady numerical simulation analysis of the four models is carried out and the dipole source of pump shell is extracted. The constraint modal of pump, interior sound pressure level (SPL), exterior acoustic directivity and sound power level are obtained. The results show that five and six SPL peaks appear at BPF and blade frequency multiplier in the pump inlet and outlet, respectively, the SPL peak value is the largest at blade passing frequency (BPF), and the interior acoustics propagates to inlet and outlet directions, and to outlet more significantly. The exterior acoustic directivity in the four models is the same in all directions, and the blade outlet angle has little influence on the changes of exterior acoustic directivity. The SPL at BPF and 2BPF in Y = 0 plane is significantly smaller than that in X = 0 and Z = 0 planes, and the difference of maximum SPL at BPF is 7.2 dB and 8.0 dB and that at 2BPF is 7.6 dB and 6.4 dB, respectively. The sound power level is maximum at 2BPF, and that at the BPF and 2BPF increases first and then decreases with the blade outlet angle increases. When the blade outlet angle is 40o, the interior and exterior acoustic performances are better. The experimental value of the SPL in model 35 is basically consistent with the simulated value, which fully indicates that the numerical simulation analysis has high accuracy and provides support for the credibility of the acoustic simulation results.

Effects of top vent locations and gasoline volumes on vented gasoline vapor explosion in closed small-scale vessel

In this study, experiments are conducted with a small-scale vessel (cross section of 100 mm × 100 mm and length of 1000 mm) to investigate the effects of a 60 mm × 60 mm vent set on the vessel roof in vented gasoline vapor explosion. Different vent locations and gasoline volumes are considered and compared. The results indicate that the initial gasoline volumes significantly affect the color and propagation characteristics of the flame generated by the explosion. Violent turbulence occurs around the side vent when the flame is ejected through it, and the turbulence near the side vent becomes more intense as the distance between the side vent and the ignitor increases. Subsequently, flame-oscillating propagation behavior is observed. The amplitude of the flame oscillating propagation decreases as the distance between the side vent and the ignitor increases. The maximum explosion overpressure and deflagration index in the pipeline increase linearly as the distance between the side vent and the ignitor increases. The release of power of the gasoline vapor explosion damage can be significantly enhanced by reducing the distance between the side vent and the ignitor. However, a shorter distance between the side vent and the ignitor prolongs the explosion noise, which is harmful to the human ear. The side vent locations and gasoline volumes have negligible effect on the maximum sound pressure level of the explosion noise, which is approximately 120 dB in all cases. Additionally, the flame propagation dynamic process can be reflected to some extent by the change curve of the sound pressure level.

Medidas vocais aerodinâmicas de cantores profissionais

O objetivo do trabalho foi caracterizar as medidas vocais aerodinâmicas de cantores profissionais conforme o sexo e os valores de referência. Trata-se de estudo transversal, quantitativo e retrospectivo com 23 cantores profissionais entre 19 a 55 anos de idade. Analisaram-se os registros dos tempos máximos de fonação de /a/, /i/, /u/, /s/, /z/, /e/, /ė/; níveis de pressão sonora; e relações s/z e ė/e. Os dados foram analisados estatisticamente. Os homens apresentaram tempos máximos de fonação de /e/, /i/ e /u/ significativamente abaixo dos valores de referência e as mulheres mostraram valores significativamente rebaixados do tempo máximo de fonação de /e/ e valores de tempos máximos de fonação de /i/ e /u/ significativamente dentro do esperado. Os níveis de pressão sonora habitual e níveis de pressão sonora máximo se apresentaram significativamente maiores do que os valores de referência em ambos os sexos. Concluiu-se que, no grupo de cantores profissionais analisado, os resultados dos tempos máximos de fonação sugerem maior incoordenação no controle respiratório e glótico da emissão prolongada nos homens. Os resultados dos níveis de pressão sonora sugerem maior esforço vocal na emissão para ambos os sexos, sugerindo maior esforço vocal na emissão, ou ajustes devidos ao treinamento muscular inerente à profissão.

A New Signal for Measuring Loudspeaker Maximum Linear SPL

To determine which loudspeakers are sized appropriately for a particular application, it is necessary to have a standard test signal. Test signals exists which intend to represent the frequency-dependent root mean square (RMS) level of typical content. However, the peak-to-average ratio (crest factor) of typical signals is also important for determining the maximum level a loudspeaker can attain. The crest factor of real signals as a function of frequency has been investigated and it is found that the crest factor increases with increasing frequency. On the other hand, the crest factor of pink noise and other standard noise signals changes minimally with frequency. A new test signal with the crest factor as a function of frequency is modeled after real signals. A procedure for finding the maximum sound pressure level (SPL) at which a loudspeaker can reproduce this signal linearly is proposed. Both the signal and the procedure have been made publicly available so that comparable measurements can be made by multiple, independent individuals .

0282 Correlation Between Sleep Depth in the Right and Left Cerebral Hemispheres Following Sleep Deprivation, Restriction or Noise Exposure

Abstract Introduction The Odds-Ratio-Product (ORP) is a highly-validated continuous index of sleep depth (range 0=deep sleep; 2.5=full wakefulness). ORP values fluctuate within this range as sleep state changes between wake and different sleep stages. In healthy non-sleep deprived adults, intra-class correlation coefficient of concurrent right vs. left ORP values (R / L coefficient) is typically &amp;gt;0.80. In a recent study R / L coefficient was markedly reduced in many critically-ill patients and these patients failed to be weaned from mechanical ventilation. Given the high prevalence of sleep loss in such patients we hypothesized that reduction in R/L coefficient might result from sleep loss. This retrospective EEG analysis of data from 3 independent research studies investigated if R / L coefficient decreases in pure models of sleep deprivation, restriction or noise exposure during sleep in healthy subjects. Methods Polysomnograms were obtained from three studies: A) 200 subjects who underwent 36 hours of total sleep deprivation; B) 21 subjects who underwent 4 consecutive nights of sleep restriction (5 hrs. / night); C) 72 subjects who were exposed to intermittent traffic noise events with maximum sound pressure levels ranging from 45–65 dB(A) for 10 consecutive nights. For study A, R / L coefficient was calculated from pre- and post-deprivation sleep studies and the two values were compared. For study B, coefficient was calculated at baseline and in each restriction night. For study C, the coefficient was calculated in each of the 10 exposure nights and the slope of the change was calculated. Results In study A, the coefficient decreased from 0.82±0.12 at baseline to 0.74±0.16 after sleep deprivation (p &amp;lt 0.0001). In study B, the coefficient decreased from 0.83±0.11 at baseline to 0.75±0.15 on the 4th restriction night (p &amp;lt 0.01). In study C, coefficient decreased at a rate of 0.003±0.001 per exposure night (p &amp;lt 0.001). Conclusion The correlation between sleep depth in the right and left hemispheres deteriorates following sleep deprivation, restriction or noise-induced sleep fragmentation. Support NIH P50 HL060287

Investigation of turbulence-induced quadrupole source acoustic characteristics of a three-dimensional hydrofoil

In order to investigate the turbulence-induced acoustic characteristics of hydrofoils, the flow and sound field for a model NH-15-18-1 asymmetric hydrofoil were calculated based on the mixed method of large eddy simulation (LES) with Lighthill analogy theory. Unsteady fluid turbulent stress source around the hydrofoil were selected as the inducements of quadrupole sound. The average velocity along the mainstream direction was calculated for different Reynolds numbers [Formula: see text]. Compared to experimental measurements, good agreement was seen over a range of [Formula: see text]. The results showed that the larger the [Formula: see text], the larger the vortex intensity, the shorter the vortex initial shedding position to the leading edge of the hydrofoil, and the higher the vortex shedding frequency [Formula: see text]. The maximum sound pressure level (SPL) of the hydrofoil was located at the trailing edge and wake of the hydrofoil, which coincided with the velocity curl [Formula: see text] distribution of the flow field. The maximum SPL of the sound field was consistent with the location of the vortex shedding. There were quadratic positive correlations between the total sound pressure level (TSPL) and the maximum value of the vortex intensity [Formula: see text] and velocity curl, which verified that shedding and diffusion of vortices are the fundamental cause of the generation of the quadrupole source noise.