A multi-criteria approach to optimization of acoustic feedback detection

2021 ◽  
Vol 184 ◽  
pp. 108276
Author(s):  
Elena V. Ravve ◽  
Zeev Volkovich
Keyword(s):  
Acoustic Feedback

Self-monitoring in speech production: effects of verbal hallucinations and negative symptoms

1994 ◽  
Vol 24 (3) ◽  
pp. 749-761 ◽  
Author(s):  
I. Leudar ◽  
P. Thomas ◽  
M. Johnston
Keyword(s):  
Speech Production ◽  
Error Detection ◽  
Negative Symptoms ◽  
Self Monitoring ◽  
Acoustic Feedback ◽  
Production Effects ◽  
Internal Error

SynopsisThis paper reports results of a study on self-monitoring in speech production. Thirty schizophrenics, varying in verbal hallucination and in negative symptoms status, and 17 controls were tested on the reporter test. The position of interruptions of the speech-flow to repair errors was used to indicate whether the detection of the errors was through monitoring of internal phonetic plans or through external acoustic feedback. We have found that the internal error detection was twice as frequent in controls as in schizophrenics. The relevance of this finding to Frith's (1992) model of schizophrenia is discussed. Our conclusion is that the problem with internal monitoring of phonetic plans is common to all schizophrenics, and not just to those with verbal hallucinations.

A Selective Fast Fourier Filtering Approach Applied to High Frequency Thermoacoustic Instability Analysis

2017 ◽  
Author(s):  
Felix Grimm ◽  
Jean-Michel Lourier ◽  
Oliver Lammel ◽  
Berthold Noll ◽  
Manfred Aigner
Keyword(s):  
Heat Release ◽  
High Frequency ◽  
Compressible Flows ◽  
Acoustic Pressure ◽  
Inverse Transformation ◽  
Turbulent Heat ◽  
Thermoacoustic Instability ◽  
Acoustic Feedback ◽  
Fourier Filtering ◽  
Filtering Approach

A method for selective, frequency-resolved analysis of spatially distributed, time-coherent data is introduced. It relies on filtering of Fourier-processed signals with periodic structures in frequency-domain. Therefrom extracted information can be analyzed in both, frequency- and time-domain using an inverse transformation ansatz. In the presented paper, the approach is applied to a laboratory scale, twelve nozzle FLOX®-GT-burner for the investigation of high-frequency thermoacoustic pressure oscillations and limit-cycle mechanisms. The burner is operated at elevated pressure for partially premixed combustion of a hydrogen and natural gas mixture with air. At a certain amount of hydrogen addition to fuel injection, the burner exhibits self-sustained high-frequency thermoacoustic oscillation. This unstable operation is simulated with the fractional step approach SICS (Semi Implicit Characteristic Splitting), a pressure based solver extension of the Finite Volume based research code THETA (Turbulent Heat Release Extension for the TAU Code) for the treatment of weakly compressible flows with combustion. A hybrid LES/URANS simulation delivers time-resolved simulation data of the thermoacoustically unstable operation condition, which is analyzed with the presented SFFFA (Selective Fast Fourier Filtering Approach). Acoustic pressure distribution in the combustion chamber is explicitly resolved and assigned to different characteristic modes by signal decomposition. Furthermore, the SFFFA is used for the analysis of acoustic feedback mechanism by investigating filtered transient heat release, acoustic pressure, velocity and mixture fraction. Coherent structures in flow field and combustion as well as periodic convective processes are resolved and linked to transient acoustic pressure, extensively describing the acoustic feedback of the examined burner configuration.

Effect of Acoustic Feedback on Lagrangian Coherent Structures in a Backward Facing Step Combustor With a Partially Premixed Flame

2017 ◽  
Author(s):  
Ramgopal Sampath ◽  
S. R. Chakravarthy
Keyword(s):  
Coherent Structures ◽  
Large Scale ◽  
Pressure Oscillation ◽  
Velocity Fields ◽  
Premixed Flame ◽  
Time Resolved ◽  
Acoustic Feedback ◽  
Acoustic Characterization ◽  
Partially Premixed ◽  
Partially Premixed Flame

The thermoacoustic oscillations of a partially premixed flame stabilized in a backward facing step combustor are studied at a constant equivalence ratio in long and short combustor configurations corresponding to with and without acoustic feedback respectively. We perform simultaneous time-resolved particle image velocimetry (TR-PIV) and chemiluminescence for selected flow conditions based on the acoustic characterization in the long combustor. The acoustic characterization shows a transition in the dominant pressure amplitudes from low to high magnitudes with an increase in the inlet flow Reynolds number. This is accompanied by a shift in the dominant frequencies. For the intermittent pressure oscillations in the long combustor, the wavelet analysis indicates a switch between the acoustic and vortex modes with silent zones of relatively low-pressure amplitudes. The short combustor configuration indicates the presence of the vortex shedding frequency and an additional band comprising the Kelvin Helmholtz mode. Next, we apply the method of finite-time Lyapunov exponent (FTLE) to the time-resolved velocity fields to extract features of the Lagrangian coherent structures (LCS) of the flow. In the long combustor post transition with the time instants with dominant acoustic mode, a large-scale modulation of the FTLE boundaries over one cycle of pressure oscillation is evident. Further, the FTLEs and the flame boundaries align each other for all phases of the pressure oscillation. In the short combustor, the FTLEs indicate the presence of small wavelength waviness that overrides the large-scale vortex structure, which corresponds to the vortex shedding mode. This behaviour contrasts with the premixed flame in the short combustor reported earlier in which such large scales were found to be seldom present. The presence of the large-scale structures even in the absence of acoustic feedback in a partially premixed flame signifies its inherent unstable nature leading to large pressure amplitudes during acoustic feedback. Lastly, the FTLE boundaries provide the frequency information of the identified coherent structure and also acts as the surrogate flame boundaries that are estimated from just the velocity fields.

Improvement of rotary encoders in human-machine-interfaces through optimized acoustic feedback

2011 ◽  
Vol 130 (2) ◽  
pp. EL57-EL61 ◽  
Author(s):  
Alexander S. Treiber ◽  
Gerhard Gruhler ◽  
Gregor Rozinaj
Keyword(s):  
Acoustic Feedback ◽  
Human Machine Interfaces

scholarly journals FUNCTIONAL DIFFERENTIAL AND DIFFERENTIAL MODELS OF SYSTEMS WITH ACOUSTICAL FEEDBACK

2019 ◽  
Vol 2019 (4) ◽  
pp. 60-67
Author(s):  
Валерий Ермолаев ◽  
Valeriy Ermolaev ◽  
Юрий Кропотов ◽  
Yuriy Kropotov ◽  
Наталья Холкина ◽  
...  
Keyword(s):  
Sound Propagation ◽  
Feedback Mechanism ◽  
Warning Systems ◽  
Multiple Reflections ◽  
Nonlinear Functional ◽  
Acoustic Feedback ◽  
Feedback Model ◽  
Geometric Acoustics ◽  
Functional Differential ◽  
Analysis Of Stability

The paper reports the investigations of the functional differential and differential models of system with acoustic feedback. The aim of the work is a for-mation, analysis and identification of linear and nonlinear functional differential models of echo, reverberation and acoustic feedback; the analysis of model sensitivity, the analysis of stability of telecommunication systems with the acoustic feedback. There is presented a mechanism of an acoustic feedback mechanism formation. At the analysis of sound propagation in closed rooms with the use of the geometric acoustics method there is obtained a nucleus equation which is approximated by nonnegative functions taking into account a model of reverberation and a model of multiple reflections. The considered procedure of echo formation and reverberation is an element of the feedback model common for warning systems and technological communication. There is investigated a model of acoustic systems with delayed feedback. A diagram of the kernel of a functional differential equation describing a system with feedback is shown. The models of systems with acoustic feedback presented in this work ensure the approximation to reality at that, an account of possibilities of the emergence in channels of non-linear distortion sound propagation are considered to be the next problem.

Saccadic Eye Movements in the Presence of Acoustic Feedback

1976 ◽  
Vol 43 (3) ◽  
pp. 898-898
Author(s):  
L. Mitrani ◽  
N. Yakimoff ◽  
St. Mateeff ◽  
G. Dimitrov
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Acoustic Feedback
Sign in / Sign up

Export Citation Format

Share Document