Reconstruction of the free-field radiation from a vibrating structure based on measurements in a noisy environment

2013 ◽  
Vol 134 (4) ◽  
pp. 2823-2832 ◽  
Author(s):  
Chuan-Xing Bi ◽  
Ding-Yu Hu ◽  
Yong-Bin Zhang ◽  
J. Stuart Bolton
Keyword(s):  
Free Field ◽  
Noisy Environment ◽  
Field Radiation

scholarly journals STABLE MATCHED LAYER FOR THE ACOUSTIC CONSERVATION EQUATIONS IN THE TIME DOMAIN

2012 ◽  
Vol 20 (01) ◽  
pp. 1250004 ◽  
Author(s):  
ANDREAS HÜPPE ◽  
MANFRED KALTENBACHER
Keyword(s):  
Time Domain ◽  
Free Field ◽  
Auxiliary Variables ◽  
Weak Stability ◽  
Absorption Properties ◽  
Conservation Equations ◽  
Convolution Integrals ◽  
Field Radiation ◽  
The Time Domain ◽  
Radiation Conditions

In recent years the development of free field radiation conditions in the time domain has become a topic of intensive research. Perfectly matched layer (PML) approaches for the frequency domain are well known. In the time domain, on the other hand, they suffer in many cases from highly increased complexity and instabilities. In this paper, we introduce a PML for the conservation equations of linear acoustics. The used formulation requires three auxiliary variables in 3D and circumvents thereby convolution integrals and higher order time derivatives. Furthermore, we prove the weak stability of the proposed formulation and show their good absorption properties by means of numerical examples.

Recovery of non-stationary free field based on pressure and acceleration measurements in a noisy environment

2019 ◽  
Vol 453 ◽  
pp. 25-40 ◽  
Author(s):  
Lin Geng ◽  
Liang Yu ◽  
Meng-Lin Mu ◽  
Chun-Dong He ◽  
Bo Yan
Keyword(s):  
Free Field ◽  
Noisy Environment

THE ROLE OF THE DIRECT TRANSFER MATRIX AS A CONNECTIVITY MATRIX AND APPLICATION TO THE HELMHOLTZ EQUATION IN 2D: RELATION TO NUMERICAL METHODS AND FREE FIELD RADIATION EXAMPLE

2005 ◽  
Vol 13 (02) ◽  
pp. 341-363 ◽  
Author(s):  
F. X. MAGRANS ◽  
O. GUASCH
Keyword(s):  
Numerical Methods ◽  
Helmholtz Equation ◽  
Transfer Functions ◽  
Free Field ◽  
Connectivity Matrix ◽  
Direct Transfer ◽  
Two Dimensional ◽  
Linear Network ◽  
Field Radiation

The Direct Transfer Function (DTF) matrix was developed in the framework of the Global Transfer Direct Transfer (GTDT) method of transmission path analysis. This method aims at solving the problem of transmission paths among subsystems from a general N-dimensional linear network, representing a vibro-acoustical model under study. The DTF matrix can be calculated from the Global Transfer Functions (GTFs), which are measurable quantities, and it is built from all the Direct Transfer Functions (DTFs) between subsystem pairs. The DTFs allow to define transmission paths by relating the signals between two network subsystems when the remaining ones become somehow blocked. In this paper, the role of the DTF matrix as a connectivity matrix is first shown by solving the Helmholtz equation in a two-dimensional grid. The results are compared with those arising from the analysis of the stencils of various numerical methods. Some finite difference and finite element methods have been considered. The connectivity role of the DTF matrix is also elucidated by means of a free field radiation example.

The Effect of Nonlinear Amplitude Growth on the Speech Perception Benefits Provided by a Single-Sided Vocoder

2019 ◽  
Vol 62 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Jessica M. Wess ◽  
Joshua G. W. Bernstein
Keyword(s):  
Transfer Functions ◽  
Spatial Configuration ◽  
Free Field ◽  
Spatial Separation ◽  
Compression And Expansion ◽  
Interaural Difference ◽  
Interaural Differences ◽  
Single Sided Deafness ◽  
Perceptual Separation ◽  
Loudness Growth

PurposeFor listeners with single-sided deafness, a cochlear implant (CI) can improve speech understanding by giving the listener access to the ear with the better target-to-masker ratio (TMR; head shadow) or by providing interaural difference cues to facilitate the perceptual separation of concurrent talkers (squelch). CI simulations presented to listeners with normal hearing examined how these benefits could be affected by interaural differences in loudness growth in a speech-on-speech masking task.MethodExperiment 1 examined a target–masker spatial configuration where the vocoded ear had a poorer TMR than the nonvocoded ear. Experiment 2 examined the reverse configuration. Generic head-related transfer functions simulated free-field listening. Compression or expansion was applied independently to each vocoder channel (power-law exponents: 0.25, 0.5, 1, 1.5, or 2).ResultsCompression reduced the benefit provided by the vocoder ear in both experiments. There was some evidence that expansion increased squelch in Experiment 1 but reduced the benefit in Experiment 2 where the vocoder ear provided a combination of head-shadow and squelch benefits.ConclusionsThe effects of compression and expansion are interpreted in terms of envelope distortion and changes in the vocoded-ear TMR (for head shadow) or changes in perceived target–masker spatial separation (for squelch). The compression parameter is a candidate for clinical optimization to improve single-sided deafness CI outcomes.

Underlying Structure of Auditory-Visual Consonant Perception by Hearing-Impaired Children and the Influences of Syllabic Compression

1988 ◽  
Vol 31 (2) ◽  
pp. 156-165 ◽  
Author(s):  
P. A. Busby ◽  
Y. C. Tong ◽  
G. M. Clark
Keyword(s):  
Hearing Aids ◽  
Free Field ◽  
Acoustic Parameter ◽  
Hearing Impaired ◽  
Visual Signal ◽  
Underlying Structure ◽  
Choice Procedure ◽  
Release Times ◽  
Impaired Children ◽  
Hearing Impaired Children

The identification of consonants in a/-C-/a/nonsense syllables, using a fourteen-alternative forced-choice procedure, was examined in 4 profoundly hearing-impaired children under five conditions: audition alone using hearing aids in free-field (A),vision alone (V), auditory-visual using hearing aids in free-field (AV1), auditory-visual with linear amplification (AV2), and auditory-visual with syllabic compression (AV3). In the AV2 and AV3 conditions, acoustic signals were binaurally presented by magnetic or acoustic coupling to the subjects' hearing aids. The syllabic compressor had a compression ratio of 10:1, and attack and release times were 1.2 ms and 60 ms. The confusion matrices were subjected to two analysis methods: hierarchical clustering and information transmission analysis using articulatory features. The same general conclusions were drawn on the basis of results obtained from either analysis method. The results indicated better performance in the V condition than in the A condition. In the three AV conditions, the subjects predominately combined the acoustic parameter of voicing with the visual signal. No consistent differences were recorded across the three AV conditions. Syllabic compression did not, therefore, appear to have a significant influence on AV perception for these children. A high degree of subject variability was recorded for the A and three AV conditions, but not for the V condition.

Human Event-Related Potentials to Higher-Order Acoustic Spatial Changes

2002 ◽  
Vol 16 (2) ◽  
pp. 114-118 ◽  
Author(s):  
Timo Ruusuvirta ◽  
Heikki Hämäläinen
Keyword(s):  
Working Memory ◽  
Mismatch Negativity ◽  
Spatial Information ◽  
Free Field ◽  
Event Related Potentials ◽  
Negative Polarity ◽  
Positive Polarity ◽  
Spatial Changes ◽  
Related Potentials ◽  
Human Event

Abstract Human event-related potentials (ERPs) to a tone continuously alternating between its two spatial loci of origin (middle-standards, left-standards), to repetitions of left-standards (oddball-deviants), and to the tones originally representing these repetitions presented alone (alone-deviants) were recorded in free-field conditions. During the recordings (Fz, Cz, Pz, M1, and M2 referenced to nose), the subjects watched a silent movie. Oddball-deviants elicited a spatially diffuse two-peaked deflection of positive polarity. It differed from a deflection elicited by left-standards and commenced earlier than a prominent deflection of negative polarity (N1) elicited by alone-deviants. The results are discussed in the context of the mismatch negativity (MMN) and previous findings of dissociation between spatial and non-spatial information in auditory working memory.

Spatial audio displays for speech communications: A comparison of free field and virtual acoustic environments

1999 ◽  
Author(s):  
W. Todd Nelson ◽  
Robert S. Bolia ◽  
Mark A. Ericson ◽  
Richard L. McKinley
Keyword(s):  
Free Field ◽  
Spatial Audio ◽  
Acoustic Environments
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