Electroacoustic Analysis Research Articles

Active feedforward noise control and signal tracking of headsets: Electroacoustic analysis and system implementation.

Active noise control (ANC) of headsets is revisited in this paper. An in-depth electroacoustic analysis of the combined loudspeaker-cavity headset system is conducted on the basis of electro-mechano-acoustical analogous circuits. Model matching of the primary path and the secondary path leads to a feedforward control architecture. The ideal controller sheds some light on the key parameters that affect the noise reduction performance. Filtered-X least-mean-squares algorithm is employed to implement the feedforward controller on a digital signal processor. Since the relative delay of the primary path and the secondary path is crucial to the noise reduction performance, multirate signal processing with polyphase implementation is utilized to minimize the effective analog-digital conversion delay in the secondary path. Ad hoc decimation and interpolation filters are designed in order not to introduce excessive phase delays at the cutoff. Real-time experiments are undertaken to validate the implemented ANC system. Listening tests are also conducted to compare the fixed controller and the adaptive controller in terms of noise reduction and signal tracking performance for three noise types. The results have demonstrated that the fixed feedforward controller achieved satisfactory noise reduction performance and signal tracking quality.

Expanding the Horizon of Electroacoustic Music Analysis. Ed. by Simon Emmerson and Leigh Landy.

Expanding the Horizon of Electroacoustic Music Analysis. Ed. by Simon Emmerson and Leigh Landy.

A method of acoustic analysis for detection of bacteriophage-infected microbial cells

The dependence of the changes of physical parameters of the suspension of Azospirillum brasilense Sp7 cells infected by FAb-Sp7 bacteriophage on their number and exposure time was studied using a biological sensor based on a piezoelectric resonator with a lateral electric field. The change in the value of the analytical signal was recorded at 1 minute from the beginning of the infection of the cells by bacteriophage. The selectivity of the action of the FAb-Sp7 bacteriophage was studied for Azospirillum brasilense (strains Cd, Sp107, Sp245, Jm6B2, Br14, KR77, S17, S27, SR55, and SR75), A. lipoferum (strains Sp59b, SR65, and RG20a), A. halopraeferans Au4, Nitrospirillum amazonense Am14, Niveispirillum irakense (strains KBC1 and KA3) bacteria, as well as for heterologous bacteria of the genera Escherichia coli (strains XL-1 and B-878), Pseudomonas putida (strains C-11 and BA-11), and Acinetobacter calcoaceticum A-122. The limit of the reliable determination of the concentration of microbial cells during bacteriophage infection process was found: ~104 cells/mL. At the same time, the presence of heterologous cell cultures (E. coli XL-1 cells) did not complicate the detection. It was shown that the method of electroacoustical analysis of cell suspensions can be used for the detection of microbial cells of Azospirillum infected by the FAb-Sp7 bacteriophage. The results are promising for the development of methods for determining and controlling the number of soil microorganisms.

Use of mini-antibodies for detection of bacteriophages by the electroaucoustic analysis method

The possibility of detecting bacteriophages using phage mini-antibodies by the electroacoustic analysis method using bacteriophages FA1-59b was shown. It was found that the frequency dependence of the real and imaginary parts of the electrical impedance of a resonator with a suspension of phages and the appropriate antibodies significantly differs from that of the resonator with a control virus suspension without addition of mini-antibodies. The amount of FAl-Sp59b bacteriophage in the analyzed suspension varied from ~1010 to 106 phage/mL; the analysis did not take longer than 5 min. The change in the real or imaginary parts of the electrical impedance at the fixed frequency near the resonance after addition of specific mini-antibodies in the suspension appeared to be an optimal information parameter to obtain reliable information. These results may allow the development of a biological sensor to identify and quantify viruses in the liquid phase.

Do Modern Hearing Aids Meet ANSI Standards?

The American National Standards Institute (ANSI) provides standards used to govern standardization of all hearing aids. If hearing aids do not meet specifications, there are potential negative implications for hearing aid users, professionals, and the industry. Recent literature has not investigated the proportion of new hearing aids in compliance with the ANSI specifications for quality control standards when they arrive in the clinic before dispensing. The aims of this study were to determine the percentage of new hearing aids compliant with the relevant ANSI standard and to report trends in electroacoustic analysis data. New hearing aids were evaluated for quality control via the ANSI S3.22-2009 standard. In addition, quality control of directional processing was also assessed. Seventy-three behind-the-ear hearing aids from four major manufacturers, that were purchased for clinical patients were evaluated before dispensing. Audioscan Verifit (version 3.1) hearing instrument fitting system was used to complete electroacoustic analysis and directional processing evaluation of the hearing aids. Frye's Fonix 8000 test box system (Fonix 8000) was also used to cross-check equivalent input noise (EIN) measurements. These measurements were then analyzed for trends across brands and specifications. All of the hearing aids evaluated were found to be out of specification for at least one measure. EIN and attack and release times were the measures most frequently out of specification. EIN was found to be affected by test box isolation for two of the four brands tested. Systematic discrepancies accounted for ∼93% of the noncompliance issues, while unsystematic quality control issues accounted for the remaining 7%. The high number of systematic discrepancies between the data collected and the specifications published by the manufacturers suggests there are clear issues related to the specific protocols used for quality control testing. These issues present a significant barrier for hearing aid dispensers when attempting to accurately determine if a hearing aid is functioning appropriately. The significant number of unsystematic discrepancies supports the continued importance of quality control measures of new and repaired hearing aids to ensure that the device is functioning properly before it is dispensed and to avoid future negative implications of fitting a faulty device.

Immunodetection of bacteriophages by a piezoelectric resonator with lateral electric field

It has been demonstrated that electroacoustic analysis with polyclonal antibodies can be used for bacteriophage detection. The frequency dependences of the real and imaginary parts of electrical impedance of a resonator with a viral suspension with antibodies were shown to be essentially different from the dependences of a resonator with control viral suspension without antibodies. It was shown that ΦAl-Sp59b bacteriophages were detected with the use of antibodies in the presence of foreign virus particles. The ΦAl-Sp59b bacteriophage content in the analyzed suspension was ~1010–106 phages/mL; the time of analysis was no more than 5 min. The optimally informative parameter for obtaining reliable information was the change in the real or imaginary part of electrical impedance at a fixed frequency near the resonance upon the addition of specific antibodies to the analyzed suspension. It was demonstrated that the interaction between bacteriophages and antibodies can be recorded, offering good prospects for the development of a biological sensor for liquid-phase identification and virus detection.

Application of the method of electro-acoustical analysis for the detection of bacteriophages in a liquid phase

The possibility of the application of electro-acoustic analysis for the detection of bacteriophages was demonstrated for the first time based on the example of the interaction of the FA1-Sp59b bacteriophage with bacterial cells of the strain Azospirillum lipoferum Sp59b. Piezoelectric cross-field resonators with a 1-mL chamber for analyzed liquid were used as the biological sensor. It was revealed that the dependences of the real and imaginary parts of the electrical impedance of the resonator loaded with a suspension of viruses and microbial cells on the frequency was significantly different from those dependences of the resonator that contained a control cell suspension without the virus. It was shown that detection of the FA1-Sp59b bacteriophage using microbial cells was possible with both extraneous viral particles and extraneous microbial cells. The proposed method allows one to accurately determine the type of identified virus after a 5-minute interaction with indicating bacterial culture. As well, the minimum concentration of viruses is five virus particles per cell. These results as a whole demonstrate the possibility of detecting specific interactions of bacteriophages with microbial cells and provide a basis for the development of a biological sensor for the quantitative detection of viruses directly in the liquid phase.

The OREMA Project: A call for the liberation of sound analysis

Following Edgard Varèse’s influential lectures – translated and documented in ‘The Liberation of Sound’ – electroacoustic music has spawned many different styles and genres. His argument was for composers to follow their imagination and not be bound to the constraints of musical notation. This, arguably, was one of the catalysts for the emergence of electroacoustic musical works. With past and recent technological advancement, the varieties of genres and styles within electroacoustic music have only expanded, challenging the notion of how one could analyse such works. It is therefore unsurprising that there is no general consensus on analytical methodologies. But for an art form that celebrates all musical possibilities should the analysis of such musics be constraint to a set number of formalised analytical methodologies?Rather than propose a new all-encompassing methodology, this article will argue for a universal approach to electroacoustic music analysis and the liberation of sound analysis. The concept of an analytical community (a community that accepts multiple analyses whilst encouraging practitioners to find new and innovative ways to analyse such works) will be raised as a means to address the issues facing electroacoustic music analysis, using the OREMA (Online Repository for Electroacoustic Music Analysis) project as an example of such an initiative.

Determination of the spectrum of lytic activity of bacteriophages by the method of acoustic analysis

The changes in the electro-acoustic parameters of cell suspension due to the interaction of cells with bacteriophages both in a pure. culture and in the presence of extraneous microflora were investigated. It has been found that the specific changes in the electroacoustic parameters of cell suspension under the action of bacteriophage occur only in microbial cells which are sensitive to the bacteriophage studied. It has been established that a sensor unit allows of distinguishing a situation when the bacterial cells are infected with specific bacteriophages of the control experiments and a situation with no introduction of infection. An approximate criterion of the presence of specific interactions of bacteriophages and cells in suspension was developed. In accordance with this criterion the change in electrical impedance of the sensor unit must not be less than - 1%. In control experiments a standard microbiological technique, plating the cells infected with bacteriophages on solid nutrient medium, was used. For the first time the possibility of using the method of electroacoustic analysis for determination of a spectrum of lytic activity of bacteriophages was shown. The results obtained may be used for development of a new express method for determining the sensitivity to bacteriophages of the microbial cells.

The Plasma-Containing Bubble Behavior Under Pulsed Discharge of Different Polarities

Bubbles generated by a pulsed discharge in water can emit extensive pulsed acoustic waves. The bubble behavior is quite important for the electroacoustic analysis. This paper presents the high-speed photographs of the plasma-containing bubble behavior under the pulsed discharges of different polarities, including a single negative bubble, single positive bubble, and bipolar bubbles. The single bubble results show that the electrobubble energy transition rate of the positive discharge is higher than that of the negative discharge. The positive bubble has longer oscillation period and lower fundamental frequency than the negative one. For the bipolar bubbles, interaction between the two bubbles influences their own behavior, irrespectively of how long the gap distance between the electrodes is, and decreases the electrobubble energy transition efficiency and the acoustic wave amplitude as well. It is also interesting that the negative bubble oscillates twice, although its energy is much lower than that of the positive bubble, and the time of the negative bubble collapse at the end of the second period almost coincides with that of the positive bubble. Finally, the positive bubble breaks into pieces and vanishes faster than the negative bubble.

Electroacoustic analysis, design, and implementation of a small balanced armature speaker.

This paper presents a new design and implementation of a balanced armature speaker (BAS), which is composed of permanent magnetic circuits, a moving armature, and a coil. The armature rocks about a pivot with the coil at one end and the permanent magnet on another. A magnetic circuit analysis is conducted for the designed BAS to formulate the force factor, which is required for modeling the coupling between the electrical and mechanical systems. In addition, an electromechanoacoustical analogous circuit is established for the BAS, which bears the same structure as the moving coil loudspeaker, except that the force factor is different. A hybrid model, which combines the lumped parameter model in the electrical and acoustical domains with a finite element model in the mechanical domain, is developed to model the high-frequency response because of the high-order modes of the membrane, the drive rod, and the armature. The electroacoustic analysis is experimentally verified. The results indicate that the sound pressure response that is simulated using the hybrid model is in superior agreement with the measured response to that simulated using the lumped parameter model.

Refined acoustic modeling and analysis of shotgun microphones

A shotgun microphone is a highly directional pickup device widely used in noisy environments. The key element that leads to its superior directivity is a tube with multiple slot openings along its length. One traditional way to model the directional response of a shotgun is to assume plane waves traveling in the tube as if it is in the free field. However, the frequency response and directivity predicted by this traveling wave model can differ drastically from practical measurements. In this paper, an in-depth electroacoustic analysis was conducted to examine the problem by considering the standing waves inside the tube with an analogous circuit containing phased pressure sources and T-networks of tube segments. A further refinement is to model the housing diffraction effect with the aid of the equivalent source method (ESM). The on-axis frequency response and directivity pattern predicted by the proposed model are in close agreement with the measurements. From the results, a peculiar bifurcation phenomenon of directivity pattern at the Helmholtz frequency was also noted. While the shotgun behaves like an endfire array above the Helmholtz frequency, it becomes a broadside array below the Helmholtz frequency. The standing wave effect can be mitigated by covering the slot openings with mesh screen, which was found to alter the shotgun response to be closer to that of the traveling wave model above a critical frequency predicted by the half-wavelength rule. A mode-switching model was developed to predict the directional responses of mesh-treated shotguns.

A Study of Hearing Aid Fitting Characteristics in Patients with Eardrum Perforation

The purpose of this study was to describe hearing aid fitting characteristics and the effects of fitting when using RECD in patients with a tympanic membrane (TM) perforation. 10 subjects with TM perforations and 8 subjects with intact TM participated in this study. RECDs were measured by using a real ear measurement system and used in fitting hearing aids through Speechmap program. Electroacoustic analysis including OSPL 90 and RESP 50 were performed in both Test-box and On-ear conditions. Aided sound field thresholds were also obtained in both conditions. There were no significant differences in hearing aid fitting characteristics and sound field aided thresholds in both Test-box and On-ear conditions for the intact TM group. However, significant differences were shown at lower frequencies below 1,000 Hz for the perforated ears in these conditions. Individual RECD is needed especially for patients with TM perforation because it can prevent from underamplification. These results suggest that individual RECD measurements are strongly recommended in fitting a hearing aid for its best outcome.

High temperature breakdown strength and voltage endurance characterization of nanofilled polyamideimide

For high temperature wire enamel application, the dielectric properties of nanoscale silica and alumina filled polyamideimide were characterized as a function of filler loading, and temperature. It was found that although the dc breakdown strength improved for both composite systems, only the alumina also exhibited an increase in ac breakdown strength. In addition, the voltage endurance at elevated temperature in both a needle/plate and twisted wire geometry was improved over a narrow range of filler loading (5-7.5 wt%). At room temperature, pulsed electroacoustic analysis (PEA) data does not indicate any difference in space charge buildup in the composite for fields up to 25 kV/mm over a period of 2 h. This is in contrast to other nanocomposite systems, which tend to show mitigation of space charge buildup with the addition of nanoparticles. Dielectric spectroscopy shows that the addition of nanoparticles increases the real permittivity above that expected for volumetric mixing rules. This enhancement is associated with high effective permittivity interfacial areas. No systematic changes in losses in the frequency range between 10-4 and 105 Hz were seen. The results suggest that carrier scattering is the primary mechanism leading to the improved breakdown strength.

Formation of thin YSZ electrolyte films by electrophoretic deposition on porous cathodes

The structure, dispersity, stability, and electrophoretic deposition (EPD) of suspensions of spherical ZrO2 stabilized Y2O3 (YSZ) nanoparticles with a mean size of 10.9 nm onto the porous surface of La0.6Sr0.4MnO3 (LSM) with a pore size of 3–20 μm were studied by electron microscopy, photon correlation spectroscopy, and electroacoustical analysis. The optimum conditions of deposition were attained by using a mixed isopropanol-acetylacetone dispersion medium, which provided the aggregative stability of the suspension with 95% individual particles. The maximum pore size on the covered surface should be up to 0.5 μm if nanoparticles with a mean diameter of 10–20 nm are used. When the pores are larger, the EPD of YSZ will be effective if an additional intermediate LSM layer is formed by EPD to provide the required pore size.

Electroacoustic analysis of an electret loudspeaker using combined finite-element and lumped-parameter models

An unconventional type of electrostatic loudspeaker is presented in this paper. The loudspeaker made of thin, light, and flexible electret material lends itself well to the space-concerned applications. Electrical impedance measurement reveals that the coupling between the electrical system and the mechanical system is weak, which renders conventional parameter identification based on electrical impedance measurement impractical. A different approach is thus employed to model the electret loudspeaker. To predict the loudspeaker's dynamic response, finite-element analysis (FEA) is conducted on the basis of a simple model and a full model. In the simple model, FEA is applied to model the electret membrane, leaving the rest of system as rigid parts. In the full model, FEA is applied to model the entire membrane-spacer-back plate assembly. Velocity response of the membrane subject to a uniformly distributed force is calculated using FEA harmonic analysis. Mechanical impedance is then calculated with the velocity response. The acoustical impedance due to the back cavity, pores, and the radiation loading at the front side is calculated by theoretical formulas. The volume velocity of the membrane and the resulting on-axis sound pressure level are predicted with electrical-mechanical-acoustical analogous circuits. The response data predicted by the simulation compare very well with experimental measurements.

FORWARD-LOOKING SESSIONS FEATURED IN EDUCATIONAL PROGRAM IN DALLAS

FORWARD-LOOKING SESSIONS FEATURED IN EDUCATIONAL PROGRAM IN DALLAS

The mechanisms leading to the useful electrical properties of polymer nanodielectrics

Polymer nanocomposites with metal oxide nanoparticle fillers exhibit enhanced electrical breakdown strength and voltage endurance compared to their unfilled or micron filled counterparts. This paper presents the following hypothesis for the mechanisms leading to improved properties. The inclusion of nanoparticles provides myriad scattering obstacles and trap sites in the charge carriers' paths, effectively reducing carrier mobility and thus carrier energy. The result is homocharge buildup at the electrodes, which increases the voltage required for further charge injection due to blocking by the homocharge. The hypothesis is supported by electroluminescence, pulsed electro acoustic analysis, thermally stimulated current measurements, a comparison of AC, DC, and impulse breakdown, as well as absorption current measurements, in silica/crosslinked polyethylene matrix composites with supporting evidence from titania/epoxy composites.

Short-Term and Long-Term Hearing Aid Benefit and User Satisfaction: A Comparison between Two Fitting Protocols

Currently published hearing aid fitting protocols recommend speech-in-noise testing and loudness measures, but it remains unclear how these measures affect hearing aid benefit and user satisfaction. This study compared two protocols in their effects on benefit and satisfaction. Protocol A included an electroacoustic analysis, real-ear measures, and hearing aid adjustments based on users' comments. Protocol B included all of Protocol A and a speech-in-noise test, loudness discomfort levels, and aided loudness. Thirty-two participants completed the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Satisfaction with Amplification in Daily Life (SADL) at 45 days and three months post-initial fitting. Fewer hearing aid adjustments were made to the hearing aids for participants fitted with Protocol B than participants fitted with Protocol A, but final gains were similar for both groups. Although similar APHAB scores were obtained for both protocols, SADL scores decreased between 45 days and three months for Protocol A.

Chlorinated organics total oxidation over V2O5/TiO2 catalysts prepared by polyol-mediated synthesis

Abstract Vanadia and titania/vanadia sols synthesized by the polyol method were used to prepare TiO2-supported catalysts. Both the modification of the V2O5 sol with a low amount of water and the use of a TiO2/V2O5 sol induced a reliable adhesion between the preformed active phases and the support, thus leading to stable catalysts. Despite the low amount of vanadium introduced in studied samples, V2O5/TiO2/WO3 catalysts were active in the o-DCB oxidation. The best results were obtained with 0.36-V2O5–TiO2 catalyst, prepared by direct impregnation with colloidal TiO2/V2O5-mixed oxides. The electroacoustic analysis indicated that the support does not show any particular electrostatic affinity for any studied sol; therefore, the higher ability of TiO2/V2O5 sol to form stable vanadium active species may possibly be explained by a better chemical affinity with the support.