Head related transfer function measurements of common PPE

2021 ◽  
Vol 263 (4) ◽  
pp. 2430-2441
Author(s):  
Megan Ewers ◽  
Sam Kincaid ◽  
Marco Beltman
Keyword(s):  
Transfer Function ◽  
Transfer Functions ◽  
Worker Safety ◽  
Protective Equipment ◽  
General Description ◽  
Field Worker ◽  
Special Ring ◽  
Head Related Transfer Function ◽  
Human Hearing ◽  
The Impact

Due to COVID 19, personal protective equipment (PPE) is now used in everyday life. Such PPE affects communication and perception. This paper provides an overview of the impact of PPE on Head Related Transfer Functions (HRTF's). Spatial acoustic effects of common PPE on human hearing can be documented to improve and inform field worker safety and communication. After a general description of the measurement process and required tools, we focus on a few methods which contribute significantly to the accuracy and analysis of PPE-based HRTF data. The dedicated setup allows measuring a full 360 degree map in automated fashion. It includes a special ring setup with 25 speakers, and a precise turn table that is used to adjust the angle of the device under test with respect to the ring. Binaural measurements were performed on a set of common PPE items on a Head And Torso Simulator (HATS) system, including hard hats, safety glasses, hearing protection, and various face masks. An overview of the data is presented.

The Intervention Component: X( It)

2019 ◽  
pp. 98-135
Author(s):  
David McDowall ◽  
Richard McCleary ◽  
Bradley J. Bartos
Keyword(s):  
Time Series ◽  
Transfer Function ◽  
Transfer Functions ◽  
Intervention Model ◽  
Intervention Component ◽  
Noise Component ◽  
Survey Knowledge ◽  
Short Course ◽  
Modeling Strategy ◽  
The Impact

Chapter 4 introduces the full ARIMA intervention model. Most substantive theories specify the intervention as an exogenous dichotomy. A Box-Tiao transfer function then distributes the intervention's response across the endogenous time series to reflect a theoretically specified onset and duration. Transfer functions allow the noise component to be parsed from the residualized time series. Theoretical specification of the intervention model requires at least some sense of the onset and duration of the impact. Detailed analyses of ten time series demonstrate how to handle interventions with abrupt and permanent, gradually accruing, gradually decaying, and complex impacts. One popular version of an ITSA short course ends with Chapter 4. Although statistically adequate ARIMA models can be built using the modeling strategy described in Chapters 3-4, survey knowledge of the auxiliary methods described in Chapter 5 is recommended.

Impact of Boundary Conditions on the Reconstructed Flame Transfer Function for Gas Turbine Combustion Systems

2008 ◽  
Author(s):  
Krzysztof Kostrzewa ◽  
Axel Widenhorn ◽  
Berthold Noll ◽  
Manfred Aigner ◽  
Werner Krebs ◽  
...  
Keyword(s):  
Transfer Function ◽  
Boundary Conditions ◽  
Gas Turbine ◽  
Transfer Functions ◽  
Feedback Mechanism ◽  
Pressure Amplitude ◽  
Flame Response ◽  
Gas Turbine Combustion ◽  
Combustion Systems ◽  
The Impact

In order to achieve low levels of pollutants modern gas turbine combustion systems operate in lean and premixed modes. However, under these conditions self-excited combustion oscillations due to a complex feedback mechanism between pressure and heat release fluctuations can be found. These instabilities may lead to uncontrolled high pressure amplitude oscillations which can damage the whole combustor. The flame induced acoustic source terms are still analytically not well described and are a major topic of thermo-acoustic investigations. For the analysis of thermo-acoustic phenomena in gas turbine combustion systems flame transfer functions can be utilized. The purpose of this paper is to introduce and to investigate modeling parameters, which could influence a novel computational approach to reconstruct flame transfer functions known as the CFD/SI method. The flame transfer function estimation is made by application of a system identification method based on Wiener-Hopf formulation. Varying acoustic boundary conditions, combustion models and time resolutions may strongly affect the reconstructed flame response characterizing overall system dynamics. The CFD/SI approach has been applied to a generic gas turbine burner to derive a flame response. 3D unsteady simulations excited with white noise have been performed and the reconstructed flame transfer functions have been validated with experimental data. Moreover, the impact on the reconstructed flame transfer functions because of different boundary condition configurations has been examined.

scholarly journals Speech intelligibility with various head-related transfer functions: A computational modeling approach

2020 ◽  
Author(s):  
Axel Ahrens ◽  
Maria Cuevas-Rodriguez ◽  
W. Owen Brimijoin
Keyword(s):  
Transfer Function ◽  
Computational Modeling ◽  
Speech Intelligibility ◽  
Transfer Functions ◽  
Spatial Separation ◽  
Spatial Position ◽  
Auditory Model ◽  
Modeling Approach ◽  
Head Related Transfer Function

AbstractSpeech intelligibility is known to be affected by the relative spatial position between target and interferers. The benefit of a spatial separation is, along with other factors, related to the head-related transfer function (HRTF). The HRTF is individually different and thus, the cues that improve speech intelligibility might also be different. In the current study an auditory model was employed to predict speech intelligibility with a variety of HRTFs. The predicted speech intelligibility was found to vary across HRTFs. Thus, individual listeners might have different access to cues that are important for speech intelligibility.

The Impact of Environmental Design on Doffing Personal Protective Equipment in a Healthcare Environment: A Formative Human Factors Trial

2017 ◽  
Vol 38 (06) ◽  
pp. 712-717 ◽  
Author(s):  
Tracey A. Herlihey ◽  
Stefano Gelmi ◽  
Joseph A. Cafazzo ◽  
Trevor N. T. Hall
Keyword(s):  
Human Factors ◽  
Personal Protective Equipment ◽  
Environmental Design ◽  
Healthcare Setting ◽  
Worker Safety ◽  
Protective Equipment ◽  
Safety Communication ◽  
Healthcare Environment ◽  
Design Changes ◽  
The Impact

OBJECTIVE To explore the impact of environmental design on doffing personal protective equipment in a simulated healthcare environment. METHODS A mixed-methods approach was used that included human-factors usability testing and qualitative questionnaire responses. A patient room and connecting anteroom were constructed for testing purposes. This experimental doffing area was designed to overcome the environmental failures identified in a previous study and was not constructed based on any generalizable hospital standard. RESULTS In total, 72 healthcare workers from Ontario, Canada, took part in the study and tested the simulated doffing area. The following environmental design changes were tested and were deemed effective: increasing prominence of color-coded zones; securing disinfectant wipes and hand sanitizer; outlining disposal bins locations; providing mirrors to detect possible contamination; providing hand rails to assist with doffing; and restricting the space to doff. Further experimentation and iterative design are required with regard to several important features: positioning the disposal bins for safety, decreasing the risk of contamination and user accessibility; optimal positioning of mirrors for safety; communication within the team; and positioning the secondary team member for optimal awareness. Additional design suggestions also emerged during this study, and they require future investigation. CONCLUSIONS This study highlights the importance of the environment on doffing personal protective equipment in a healthcare setting. Iterative testing and modification of the design of the environment (doffing area) are important to enhancing healthcare worker safety. Infect Control Hosp Epidemiol 2017;38:712–717

The impact of exercise on derived measures of central pressure and augmentation index obtained from the SphygmoCor device

2009 ◽  
Vol 106 (6) ◽  
pp. 1896-1901 ◽  
Author(s):  
Ellen A. Dawson ◽  
Mark A. Black ◽  
Jennifer Pybis ◽  
N. Timothy Cable ◽  
Daniel J. Green
Keyword(s):  
Transfer Function ◽  
Radial Artery ◽  
Vascular Tone ◽  
Transfer Functions ◽  
Applanation Tonometry ◽  
Hand Grip ◽  
Arterial Blood ◽  
Significant Difference ◽  
Blood Pressures ◽  
The Impact

The purpose of this study was to investigate whether measures derived from the SphygmoCor device and its associated transfer function are influenced by exercise-induced alterations in vascular tone. Measurements were taken from either the exercised or the contralateral nonexercised limb during repeated and identical incremental hand-grip protocols. Eight male subjects performed three 3-min bouts of hand-grip exercise on two occasions. The exercise intensities were set at 3 kg, 5 kg, with a final 1.5-kg bout performed during cuff ischemia (1.5Isch). Blood pressure waveforms were recorded from the radial artery of either the exercised or nonexercised limb using applanation tonometry (SphygmoCor) during a 90-s rest period immediately after each exercise bout. Central blood pressures and augmentation indexes (AIx), an index of arterial stiffness, were derived using the peripheral waveform and the inbuilt SphygmoCor transfer function (TF). AIx was consistently ∼10% higher in the exercised arm during all trials compared with the nonexercised limb. Similarly, there was a consistent and significant difference (∼3 mmHg; P < 0.05) between exercised and nonexercised arms for the derived central systolic and mean arterial blood pressures. Despite identical bouts of exercise, AIx and central systolic and mean arterial blood pressures derived from applanation tonometry at the peripheral radial artery were statistically different when assessed at the exercising arm vs. the nonexercising arm. Changes in vascular tone with exercise may modify the intrinsic characteristics of the vessel wall and could compromise the assumptions underlying transfer functions used to derive central measures using applanation tonometry.

scholarly journals Measurement of Head-Related Transfer Functions: A Review

2020 ◽  
Vol 10 (14) ◽  
pp. 5014 ◽  
Author(s):  
Song Li ◽  
Jürgen Peissig
Keyword(s):  
Transfer Function ◽  
Transfer Functions ◽  
Human Subjects ◽  
Near Field ◽  
Free Field ◽  
Measurement Systems ◽  
High Measurement ◽  
Head Related Transfer Function ◽  
Acoustic Environments ◽  
Acoustic Transfer Function

A head-related transfer function (HRTF) describes an acoustic transfer function between a point sound source in the free-field and a defined position in the listener’s ear canal, and plays an essential role in creating immersive virtual acoustic environments (VAEs) reproduced over headphones or loudspeakers. HRTFs are highly individual, and depend on directions and distances (near-field HRTFs). However, the measurement of high-density HRTF datasets is usually time-consuming, especially for human subjects. Over the years, various novel measurement setups and methods have been proposed for the fast acquisition of individual HRTFs while maintaining high measurement accuracy. This review paper provides an overview of various HRTF measurement systems and some insights into trends in individual HRTF measurements.

scholarly journals Seismic response of a layered soil deposit with inclusions

2021 ◽  
Vol 43 (2) ◽  
pp. 3-13
Author(s):  
O.V. Kendzera ◽  
S.V. Mykulyak ◽  
Yu.V. Semenova ◽  
I.A. Skurativska ◽  
S.I. Skurativskyi
Keyword(s):  
Transfer Function ◽  
Seismic Waves ◽  
Transfer Functions ◽  
Boundary Value ◽  
Numerical Procedure ◽  
Layered Soil ◽  
Layered System ◽  
Earthquake Resistant ◽  
Soil Deposits ◽  
The Impact

It is known that soil massifs can amplify or weaken seismic waves generated by earthquakes. Therefore, the problem of studying the impact of soil deposits on the passage of seismic waves is important in terms of the facilities in operation and the design of new earthquake-resistant objects. Soil deposits, which are allotted for building, are mainly layered. In addition, the materials in these layers are also significantly heterogeneous. To describe the dynamics of inhomogeneous soil massif, the model of an elastic continuum with oscillating non-interacting inclusions is used. Within the framework of this model, the resonant properties of multi-layered soil deposit are analyzed at the conditions of harmonic perturbations applied to the bedrock. On the basis of the solution to the boundary value problem concerning oscillations of the system subjected to the free surface and conjugation conditions on the boundaries between layers, it is derived the transfer function which characterizes the amplification of shear displacements by the layered system. Within the framework of problems on the oscillations of two- and five layered systems, the analytical studies were confirmed by numerical evaluations of transfer functions. In particular, using the built-in functions of the system «Mathematica», it is developed the numerical procedure for evaluating the frequency dependencies of amplification factor for layered Kelvin—Voigt media and media with oscillating inclusions. Moreover, for the two-layered system, it is analyzed the effect on the transfer function for the ratio of layers’ shear moduli and the ratio of the inclusions’ natural frequencies. It is also shown that the maxima in the transfer function correspond to the eigenfrequencies of the boundary value problem.The obtained results and the proposed approach to the study of the response of the layered inhomogeneous medium to vibrational perturbations can serve as a theoretical basis for earthquake-resistant design and construction.

Analytic integration of contrast transfer functions

1988 ◽  
Vol 46 ◽  
pp. 822-823
Author(s):  
Peter Rez
Keyword(s):  
Wave Function ◽  
Transfer Function ◽  
Transfer Functions ◽  
Spherical Aberration ◽  
Continuous Distribution ◽  
Objective Lens ◽  
Direction Parallel ◽  
Scattering Angle ◽  
Analytic Integration ◽  
Image Position

In high resolution microscopy the image amplitude is given by the convolution of the specimen exit surface wave function and the microscope objective lens transfer function. This is usually done by multiplying the wave function and the transfer function in reciprocal space and integrating over the effective aperture. For very thin specimens the scattering can be represented by a weak phase object and the amplitude observed in the image plane is1where fe (Θ) is the electron scattering factor, r is a postition variable, Θ a scattering angle and x(Θ) the lens transfer function. x(Θ) is given by2where Cs is the objective lens spherical aberration coefficient, the wavelength, and f the defocus.We shall consider one dimensional scattering that might arise from a cross sectional specimen containing disordered planes of a heavy element stacked in a regular sequence among planes of lighter elements. In a direction parallel to the disordered planes there will be a continuous distribution of scattering angle.

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