Specification for values for the difference between free-field and pressure sensitivity levels for one-inch standard condenser microphones

1980 ◽  
Keyword(s):  
Free Field ◽  
Pressure Sensitivity ◽  
The Difference

Discrete derivative asymptotics of the β-Hermite eigenvalues

2019 ◽  
Vol 28 (5) ◽  
pp. 657-674
Author(s):  
Gopal Goel ◽  
Andrew Ahn
Keyword(s):  
Free Field ◽  
Tridiagonal Matrix ◽  
Young Diagrams ◽  
Gaussian Free Field ◽  
Empirical Measures ◽  
Gaussian Fluctuations ◽  
Discrete Derivative ◽  
The Difference ◽  
Deterministic Limit

AbstractWe consider the asymptotics of the difference between the empirical measures of the β-Hermite tridiagonal matrix and its minor. We prove that this difference has a deterministic limit and Gaussian fluctuations. Through a correspondence between measures and continual Young diagrams, this deterministic limit is identified with the Vershik–Kerov–Logan–Shepp curve. Moreover, the Gaussian fluctuations are identified with a sectional derivative of the Gaussian free field.

Directional Hearing in the Japanese Quail (Coturnix Coturnix Japonica): II. Cochlear Physiology

1980 ◽  
Vol 86 (1) ◽  
pp. 153-170
Author(s):  
R. B. COLES ◽  
D. B. LEWIS ◽  
K. G. HILL ◽  
M. E. HUTCHINGS ◽  
D. M. GOWER
Keyword(s):  
Pressure Gradient ◽  
Free Field ◽  
Directional Hearing ◽  
Directional Sensitivity ◽  
Ear Canal ◽  
Directional Information ◽  
Cochlear Physiology ◽  
Directivity Patterns ◽  
The Difference ◽  
Sound Diffraction

The directional sensitivity of cochlear microphonics (CM) was studied inthe quail by rotating a free-field sound source (pure tones, 160-10 kHz)through 360° in the horizontal plane, under anechoic conditions. Sound diffraction by the head was monitored simultaneously by a microphone at the entrance to the ipsilateral (recorded) ear canal. Pressure-field fluctuations measured by the microphone were non-directional (≤ 4 dB) up to 4 kHz; the maximum head shadow was 8 dB at 6.3 kHz. In comparison, the CM sensitivity under went directional fluctuations ranging up to 25 dB for certain low, mid and high frequency band widths. There was noticeable variation between quail for frequencies producing maximum directional effects, although consistently poor directionality was seen near 820 Hz andto a lesser extent near 3.5 kHz. Well-defined CM directivity patterns reflected the presence of nulls (insensitive regions) at critical positions around the head and the number of nulls increased with frequency. Five major types of directivity patterns were defined using polar co-ordinates: cardioid, supercardioid, figure-of-eight, tripartite and multilobed. Such patterns were largely unrelated to head shadow effects. Blocking the ear canal contralateral to there corded ear was shown to effectively abolish CM directionality, largely by eliminating regions of insensitivity to sound. It is inferred that the quail ear functions as an asym metrical pressure gradient receiver, the pressure gradient function being mediated by the interauralcavity. It is proposed that the central auditory system codes directional information by a null detecting method and computes an unambiguous (i.e.intensity independent) directional cue. This spatial cue is achieved by the difference between the directional sensitivities of the two ears, defined as the Directional Index (DI). The spatial distribution of DI values (difference pattern) demonstrated ranges and peaks which closely reflected the extent and position of nulls determined from monaural directivity functions. Large directional cues (up to 25 dB) extended throughout most of the audible spectrum of the quail and the sharpness of difference patterns increased with frequency. Primary ‘best’ directions, estimated from peaks in difference patterns, tended to move towards the front of the head at higher frequencies; rearward secondary peaks also occurred. From the properties of directional cues it is suggested that the ability of birds to localize sound need not necessarily depend on frequency; however, spatial acuity may be both frequency and direction dependent, and include the possibility of front-torearerrors. The directional properties of bird vocalizations may need to bere assessed on the basis of the proposed mechanism for directional hearing.

scholarly journals The difference between Chirp & Click stimulation in Diagnostic Auditory Brainstem Response in assessment of hearing among age group between 1-10 years Iraqi children

2021 ◽  
Vol 23 (05) ◽  
pp. 433-444
Author(s):  
Dr. Mohammed Saeed Al-Mula Hamo ◽  
◽  
Dr. Khalid Khudhur Mulla Tohi ◽  
Dr. Mohammed Ahmed Jasim Alogaidi ◽  
◽  
...  
Keyword(s):  
Teaching Hospital ◽  
Free Field ◽  
Auditory Brainstem ◽  
Cross Sectional ◽  
Auditory Brain Stem ◽  
Health Directorate ◽  
Brainstem Response ◽  
The Mean ◽  
The Difference ◽  
Cross Sectional Design

Background: Aim: To compare the response of human auditory brain stem evoked by clicks stimuli and chirps. Patients and Methods: A study of cross-sectional design was chosen to evaluate the objective of the study. Children between 1-10 years were enrolled from the attendants of the Dept. of Surgery and Audiology, Al-Jamhoori Teaching Hospital, Ministry of Health /Nineveh health Directorate, and the outpatient clinics in al-alwiyah teaching hospital for children and done in the privet clinics of the researchers. The data collection extended over the period from 2019 January to 2020 August. A total number of 70 children involved in the study according to the parents’ complaints, full history taken and the clinical examination by otoscopy. The probable conductive problem excluded by using the Tympanometry. Moreover, free field test was done before chirp and click. Paired t-test was used for the statistical analysis. Results: The males represent (44.3%) and the females (55.7%). The mean age of children included was 49 months ± 27.7 SD. Wave V of the chirp shows lower latency means in all intensities in comparison with that of click stimuli. While waves I and III, show longer latency as the intensity go down, but the differences between chirp and click are insignificant. Wave V amplitudes getting lower values as the intensity decreasing in both chirp and click and become significantly higher than that of click. Wave I and III show decreasing amplitudes with the decreasing intensity in both chirp and click, with higher amplitudes in click in comparing with that of chirp, which are insignificant statistically down to below 70 dBnHL. Conclusions: The chirp stimuli are highly significant and more efficient from the click in the detection of hearing loss among the children regarding both latency and amplitude particularly at wave V.

scholarly journals Seismic analysis of the zaouiat ait mellal twin tunnels of Agadir motorway (Morocco)

2020 ◽  
Vol 150 ◽  
pp. 03001
Author(s):  
Abdelhay El Omari ◽  
Mimoun Chourak ◽  
Carlos Navvaro Ugena ◽  
Seif-Eddine Cherif ◽  
Mohamed Rougui ◽  
...  
Keyword(s):  
Seismic Analysis ◽  
Free Field ◽  
Bending Moment ◽  
Structural Elements ◽  
Underground Structures ◽  
Maximum Displacement ◽  
The Difference ◽  
The Stability ◽  
The One ◽  
Twin Tunnels

Underground structures, such as tunnels, are vital for ensuring all kinds of transportation; and being buried under the surface makes them exposed to soil dynamics. Added to the moderate seismic activity in Morocco, the stability of tunnels is put to the test. This paper examines the interaction between the ZAM (Zaouit Ait Mellal) twin tunnels between the cities of Marrakesh and Agadir, using the Difference Element Method provided by FLAC 2D software. The acceleration is introduced as the one related to the historic event of El centro 1940 with free-field boundary conditions in the numerical model, with three configurations: tunnel 1 without tunnel 2, tunnel 2 without tunnel 1 and tunnel 1 with tunnel 2. The results of the simulations indicate that the differences values of the maximum displacement, axial force and bending moment on structural elements are very noteworthy from the configuration of the tunnel (single) to the twin tunnels in order to prove the interaction between these latter under seismic loading.

scholarly journals Effect of Freezing-Thawing Cycle on the Mechanical Properties and Micromechanism of Red Mud-Calcium-Based Composite Cemented Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Hao Wen ◽  
Chongxian Suo ◽  
Yafen Hao ◽  
Peige Fan ◽  
Xiaoqiang Dong
Keyword(s):  
Mechanical Properties ◽  
Solid Waste ◽  
Red Mud ◽  
Energy Dispersive Spectrometer ◽  
Sem Analysis ◽  
Pressure Sensitivity ◽  
Effective Measure ◽  
Thawing Cycle ◽  
Cemented Soil ◽  
The Difference

The environmental issues caused by solid waste have become increasingly serious. Adding additive is considered as an effective measure to improve the performance of the cemented soil. Therefore, the feasibility study of solid waste such as red mud and desulfurization gypsum used in composite cemented soil is in urgent demand. In this study, the mechanical properties and durability to freezing-thawing cycle of red mud-calcium-based composite cemented soil (RMCC) were analyzed through compressive strength test, resistivity test, and freezing-thawing cycle test. The action mechanism of RMCC was revealed through a series of X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) test. The results show that the optimal red mud content in RMCC is 12%. As the freezing-thawing cycle progresses, the difference in resistivity and pressure sensitivity of RMCC gradually weakens. When the freezing-thawing cycle reaches 7, the pressure sensitivity characteristic of RMCC is lost. The change in resistivity and pressure sensitivity can be used to characterize the damage caused by the freezing-thawing cycle. Combined with XRD and SEM analysis, the presence of minerals such as K2Ca5(SO4)6·H2O and (Ca, Na)2(Si, Al)5O10·3H2O play a key role in fixation of alkali metal elements, and the coordination of CSH gel cementation effect and AFt filling effect has a significant impact on mechanical properties. The study provides an effective way to the utilization of red mud and desulfurization gypsum in subgrade strengthening.

scholarly journals Recovering the Free-Field Acoustic Characteristics of a Vibrating Structure from Bounded Noisy Underwater Environments

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5521
Author(s):  
Wei Lin ◽  
Sheng Li
Keyword(s):  
Rigid Body ◽  
Free Field ◽  
Sound Field ◽  
Coupling Method ◽  
Noisy Environments ◽  
Acoustic Characteristics ◽  
Acoustic Coupling ◽  
Vibrational Behavior ◽  
Measurement Surface ◽  
The Difference

The vibrational behavior of an underwater structure in the free field is different from that in bounded noisy environments because the fluid–structure interaction is strong in the water and the vibration of the structure caused by disturbing fields (the reflections by boundaries and the fields radiated by sources of disturbances) cannot be ignored. The conventional free field recovery (FFR) technique can only be used to eliminate disturbing fields without considering the difference in the vibrational behavior of the structure in the free field and the complex environment. To recover the free-field acoustic characteristics of a structure from bounded noisy underwater environments, a method combining the boundary element method (BEM) with the vibro-acoustic coupling method is presented. First, the pressures on the measurement surface are obtained. Second, the outgoing sound field and the rigid body scattered sound field are calculated by BEM. Then, the vibro-acoustic coupling method is employed to calculate the elastically radiated scattered sound field. Finally, the sound field radiated by the structure in the free field is recovered by subtracting the rigid body scattered sound field and the elastically radiated scattered sound field from the outgoing sound field. The effectiveness of the proposed method is validated by simulation results.

Transfer function of open ear importance in assessment of hearing protection devices noise reduction

2021 ◽  
Vol 61 (10) ◽  
pp. 655-661
Author(s):  
Ludmila V. Prokopenko ◽  
Maria V. Bulgakova ◽  
Nicolay N. Courierov ◽  
Alla V. Lagutina
Keyword(s):  
Transfer Function ◽  
Objective Assessment ◽  
Free Field ◽  
Acoustic Properties ◽  
Hearing Protection ◽  
Single Digit ◽  
Actual Problem ◽  
Uncertainty Of Measurements ◽  
Protection Devices ◽  
The Difference

Introduction. Objective assessment of the noise redaction (NR) of individual hearing protection devices (HDP) in industrial conditions is actual problem despite numerous studies in this direction in many countries. This study aimed to implement the F-MIRE method for measuring the NR of HDPs, considering the transfer function of the outer ear. Materials and methods. HDP performance indicators measured by the real ear attenuation threshold (REAT) method in the free field, do not fully reflect the protective properties of HDP in specific production conditions and for a specific employee, according to many researchers. The measurement method using two microphones, called Field-MIRE (F-MIRE), allows you to determine NR as the difference in sound pressure, external noise and noise inside the external auditory meatus (EAM). But since these microphones are located in different acoustic conditions, it becomes necessary use at least two blocks of correction coefficients to get real results. One block - considering the properties of the acoustic probe, the second - should consider the transfer function of open ear. The measurements of the TFOE in 18 volunteers and the evaluation of the NR of the SOMZ-1 "Jaguar" earmuff in industrial conditions were carried out. Results. This study has shown the effectiveness of the implementation of the F-MIRE method for an adequate assessment of the NR of earmuff in industrial conditions. The special headband uses for measuring the TFOE allows you to standardize the location of measuring microphones relative to the volunteer's head and reduce the uncertainty of measurements. Unlike the REAT method with binaural listening in a free field, the F-MIRE method allows you to determine the TFOE for each ear of an employee. Our research has shown that TFOE differences between the right and left ears one-man can be significant. Conclusion. The NR determination by the difference of sound pressures measured by an external microphone and a MIRE microphone, without considering the acoustic properties of the outer ear underestimates both spectral and single-digit NR indicators.

scholarly journals Ear-Specific Hemispheric Asymmetry in Unilateral Deafness Revealed by Auditory Cortical Activity

2021 ◽  
Vol 15 ◽  
Author(s):  
Ji-Hye Han ◽  
Jihyun Lee ◽  
Hyo-Jeong Lee
Keyword(s):  
Sound Localization ◽  
Hemispheric Asymmetry ◽  
Free Field ◽  
Binaural Hearing ◽  
Cortical Reorganization ◽  
Speech Sounds ◽  
Delayed Reaction ◽  
Unilateral Deafness ◽  
The Difference ◽  
The Right

Profound unilateral deafness reduces the ability to localize sounds achieved via binaural hearing. Furthermore, unilateral deafness promotes a substantial change in cortical processing to binaural stimulation, thereby leading to reorganization over the whole brain. Although distinct patterns in the hemispheric laterality depending on the side and duration of deafness have been suggested, the neurological mechanisms underlying the difference in relation to behavioral performance when detecting spatially varied cues remain unknown. To elucidate the mechanism, we compared N1/P2 auditory cortical activities and the pattern of hemispheric asymmetry of normal hearing, unilaterally deaf (UD), and simulated acute unilateral hearing loss groups while passively listening to speech sounds delivered from different locations under open free field condition. The behavioral performances of the participants concerning sound localization were measured by detecting sound sources in the azimuth plane. The results reveal a delayed reaction time in the right-sided UD (RUD) group for the sound localization task and prolonged P2 latency compared to the left-sided UD (LUD) group. Moreover, the RUD group showed adaptive cortical reorganization evidenced by increased responses in the hemisphere ipsilateral to the intact ear for individuals with better sound localization whereas left-sided unilateral deafness caused contralateral dominance in activity from the hearing ear. The brain dynamics of right-sided unilateral deafness indicate greater capability of adaptive change to compensate for impairment in spatial hearing. In addition, cortical N1 responses to spatially varied speech sounds in unilateral deaf people were inversely related to the duration of deafness in the area encompassing the right auditory cortex, indicating that early intervention would be needed to protect from maladaptation of the central auditory system following unilateral deafness.

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