Frequency Modulation System Research Articles

Frequency Modulation System and Bone Conduction Hearing Aid: Electroacoustic Verification.

Introduction A protocol has not yet been developed to perform electroacoustic measurements and behavioral tests to fit the frequency modulation (FM) system in bone conduction hearing aid (BCHA) users. Electroacoustic verification, with “FM transparency” achieved, ensures user audibility of FM transmitter and hearing aid signals. Objective To propose and validate a protocol for electroacoustic verification of the FM system coupled to the BCHA. Method Twenty-four sets of FM system and BCHA were submitted to electroacoustic verification, using a receiver and a plastic adapter to connect the BCHA to a 2cc coupler in the hearing instrument analyzer. The measurements were performed in the acoustic box, at 65 dB sound pressure level (SPL), with International Speech Test Signal (ISTS), first to the BCHA microphone and then to the FM system microphone, to determine the transparency, in which equivalent inputs for both microphones result in equivalent outputs. The FM gain or volume has been adjusted to try to gain transparency for the outputs of the two input devices. Results Transparency was achieved for all sets evaluated, but in some combinations, adjustments to the FM receiver gain over the manufacturer's default setting were required. Conclusion The proposed protocol proved to be effective for the electroacoustic verification of the FM system coupled to the BCHA.

Impact of Hearing Loss and Universal Face Masking in the COVID-19 Era

Impact of Hearing Loss and Universal Face Masking in the COVID-19 Era

Angle Measurement of Fuse Using Linear Frequency Modulation System Based on C6678 MultiCore DSPs

Real-time angle measurement of missiles is as important as range measurement for precision strike in modern wars and fuse using linear frequency modulation (LFM) system has been equipped widely due to its good range resolution. However, angle measurement of fuse using LFM system hasn’t been realized. In order to achieve the accurate and rapid measurement of angle, this paper firstly derives the relationship between angle and phase of beat signal in the LFM system. Secondly, an arithmetic called AapFFT-CZT is proposed by sampling and inserting zeros based on all-phase Fourier Transform (apFFT) and Chirp Z Transform (CZT). Compared with traditional Fast Fourier Transform (FFT), AapFFT-CZT has higher accuracy and better anti-noise performance when used to measure angle. Thirdly, angle measurement utilizing AapFFT-CZT is performed successfully on single core of TMS320C6678. When there is no noise, accuracy of angle measurement is within 0.01°. When there is Gaussian white noise, accuracy is still within 0.25°. Last but not least, fast and parallel measurement on multiple cores is achieved. The results show that clocks consumed when using multiple cores is just 57% of clocks consumed when using single core. Therefore, angle can be measured accurately and quickly based on C6678 multi-core DSPs.

Provision of the frequency modulation system for the hearing impaired

IntroductionThe personal frequency modulation system is an assisted technology resource used in the accessibility of individuals with hearing impairment, being very important in the school environment. Ordinance number 1274/2013 included this device into the Brazilian unified health system. ObjectiveTo analyze the distribution the personal frequency modulation system concession in the national territory by the Brazilian unified health system from 2013 to 2017. MethodsThis is an ecological study that uses the 27 federation units and the five geographic regions as analysis units. The population involved students in the age range of 5–17 years who reported severe hearing impairment. The data sources were the ambulatory information system/Brazilian unified health system, the Brazilian institute of geography and statistics and the report no. 58 of the national commission for the incorporation of technologies into Brazilian unified health system, national commission of technologies incorporation of the ministry of health. The spatial analysis was carried out through the percentage of coverage of the frequency modulation system concession per federation unit; the data were then unified in the five geographic regions and descriptive statistical analysis was performed. ResultsBetween the first and second years, there was an increase of almost 50% in the quantity dispensed, however, there was a progressive decline in the following years. The average coverage of the frequency modulation system in Brazil was 33.4%. The spatial exploratory analysis showed there is a low and uneven distribution in the territory, as the South and Southeast regions had the highest coverage and the North and Northeast regions the lowest, except for the Rio Grande do Norte unit. ConclusionThe frequency modulation system concession was below that stipulated by the ministry of health and from 2014 to 2017, the dispensed quantity progressively decreased. There is an unequal distribution in the territory that can be explained by the geographic disposition of hearing health services.

Wearable Dual-Frequency Vibrotactile System for Restoring Force and Stiffness Perception.

Recently, there has been substantial progress in the mechatronic design and myoelectric control of active prostheses. However, a significant unmet need is the lack of sensory feedback in commercial prostheses for upper-limb amputees. The lack of sensory perception impacts on the control performance and embodiment, determining relatively high rejection rates. Previous research has been conducted to evaluate various non-invasive substitutional sensory channels, mainly to regenerate haptic perception. However, providing sensory channels for stiffness perception has been much less explored. In this short paper, we propose a non-invasive wearable sensory armband, named vibrotactile frequency modulation (V-FM) system. Using the V-FM, we implement a closed-loop myocontrol system with force and stiffness perception. A user study was conducted based on a repetitive two-forced alternative choice discrimination test in six able-bodied participants. The study was designed according to the method of constant stimuli. Results showed that using the V-FM armband, the participants recovered sensation comparable (in terms of difference threshold) to the natural stiffness perception. This demonstrated the potential of the proposed V-FM armband in restoring haptic and stiffness perception non-invasively.

The effects of using hearing aids and a frequency modulated system on listening effort among adolescents with hearing loss

Objective: To develop a web-based application for a colour pattern memory recognition task as the secondary task of a dual-task paradigm and to compare the listening effort required by adolescents with hearing loss (HL) under two conditions (HA and HA + FM system), to adolescents with normal hearing (NH).Design: Cohort study. The participants underwent a dual-task paradigm, including the Hearing in Noise Test as the primary task and a colour memory task as the secondary task. A platform, PALETA, was developed to assess the secondary task.Study sample: In total, 31 adolescents were enrolled, of which 13 adolescents had HL and 18 adolescents had NH (mean age, 14 years).Results: Adolescents with NH scored significantly better on the secondary task compared to participants with HL using a HA. However, on analysing response time, no significant differences were observed among the groups.Conclusion: PALETA is proposed as a test procedure for the secondary task. The results revealed that the use of an FM system reduces the listening effort that adolescents with HL deploy to recognise speech in noise, and that listening effort data by number of correct responses is a way of investigating the benefits of using FM system.

Phrases in noise test (PINT) Brazil: effectiveness of the test in children with hearing loss

IntroductionOne of the main implications of hearing impairment is the difficulty in perceiving speech sounds, especially in noisy environments. Thus, the frequency-modulated system is considered an important educational tool for children with hearing impairment because it improves speech perception in acoustically-unfavorable environments, such as in the classroom. The assessment of speech perception in noise is included in the verification protocol of this device. ObjectivesTo verify the effectiveness of the phrases in noise test Brazil in children with hearing impairment using an frequency-modulated system. MethodsThis was a cross-sectional cohort study. The sample included 40 children, aged 4 years to 11 years and 11 months old, divided into 4 groups: (1) 10 normal hearing children; (2) 13 children with hearing aids and frequency-modulated system; (3) 12 children using cochlear implant and fitted with the frequency-modulated system; and (4) 5 children diagnosed with auditory neuropathy spectrum disorder, fitted with hearing aids and/or cochlear implant and with the frequency-modulated system. The phrases in noise test Brazil was used to evaluate speech perception in noise under the conditions with and without the frequency-modulated system. For the statistical analysis of the data, a significance level of 5% (p < 0.05) was adopted. ResultsThere was a significant difference between the groups when they were evaluated with the frequency-modulated system. The test was also validated through concurrent and convergent validation measures. Phrases in noise test Brazil is a viable option for monitoring auditory performance in noise in different groups of children with hearing impairmen. ConclusionPhrases in noise test Brazil was effective in assessing speech perception in noise and may contribute to the improvement of the indication, fitting and follow-up protocols for the frequency-modulated system use.

Effects of a wireless frequency modulation system on learning ability and emotional and behaviour problem improvement in 11 children with cochlear implant.

Effects of a wireless frequency modulation system on learning ability and emotional and behaviour problem improvement in 11 children with cochlear implant.

SRM sensorless for position control based on a frequency modulation system

This paper presents a study of a system to detect the angular position of the shaft of an 8/6 Switched Reluctance Machine (SRM) for position control. The detection system is independent of the machine circuits and is based on the indirect measurement of the induction coefficient, using a diagnostic coil. This induction coefficient, variable with the angular position, is the variable element of an oscillator, producing a frequency modulation. The intrinsic problems that this indirect position measurement system presents, particularly related with position control, are explained. The influence of the machine temperature, of the rotor speed and of the magnetic circuit saturation are also discussed.

Adaptive modulation interval filtering algorithm based on empirical mode decomposition

To improve the denoising performance of echo signal in a receiver of frequency modulated system, an adaptive modulation interval threshold denoising algorithm on the basis of empirical mode decomposition is proposed. By means of measuring the energy variation in each intrinsic mode function of noise interference and different background clutter, the optimal decomposition stopping time of empirical mode decomposition and the order of intrinsic mode functions needed to be filtered are determined. Combined with the soft interval threshold, an adjustment factor is added into the soft interval threshold formula to process the intrinsic mode function adaptively. The simulation and practical measurement results show that the proposed method improves signal-to-noise ratio by 1–3 dB and reduces the root mean square error by 10–25% compared with the direct empirical mode decomposition denoising method and traditional threshold denoising method.

Optimal Fractional Order BELBIC to Ameliorate Small Signal Stability of Interconnected Hybrid Power System

The small signal stability of power systems integrated with fallback large‐scale distributed energy resources is of utmost importance during the perturbation conditions. Among the various renewable resources in power systems: photovoltaic, fuel cell, wind turbine, diesel engine, aqua electrolyser, battery, ultra‐capacitor, and flywheel is becoming more favored in last decades. AGC, a main control system of frequency modulation, must correctly alleviate the low frequency oscillations caused by the perturbation and variable output power of renewable resources. In this regard, FOBELBIC is here introduced to enhance the damping capability of AGC. Since both the frequency and tie‐line power oscillations must be concomitantly alleviated, the small signal stability problem has been multi‐objectively formulated. Due to the exploration capability of MOALO, it has been chosen to extract the optimal parameters of FOBELBIC. Furthermore, MOPSO, MOBA, and NSGA‐II have been studied to demonstrate the capability of MOALO. To verify and validate the damping performance of suggested controller, it has been evaluated in three‐area reconstructed power system under the load perturbations as well as wind speed and sun radiation variations, and at the same time compared with BELBIC and PID controllers. Finally, the simulation results have evidently confirmed the damping the performance of MOALO‐based FOBELBIC to enhance the small signal stability of hybrid power system. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

Parameters estimation and imaging of moving target for frequency-modulated continuous-wave synthetic-aperture radar system

According to frequency-modulated continuous-wave synthetic-aperture radar, we establish the signal model of a moving target and propose an algorithm for target parameters estimation and imaging. The key procedures of moving target imaging include velocities estimation and range migration correction. Compared with conventional methods, the effect introduced from the along-track velocity is taken into account during the range migration correction to improve the correction accuracy. Moreover, fractional Fourier transform is adopted to estimate the Doppler parameters. To summarize, the proposed method has three advantages. First, by carrying out rough and precise estimation separately, both accurate velocity estimation and better robustness are obtained. Second, this method is available for moving targets with Doppler ambiguity. Third, the third-order phase error derived from moving target is taken into account to improve the azimuth compression result. Finally, a complete flowchart of the proposed method is presented and is verified by both simulation and real data.

调频连续波激光测距系统的振动补偿仿真研究

调频连续波激光测距系统的振动补偿仿真研究

The relationship between speech recognition in noise and non-speech recognition in noise test performances: Implications for central auditory processing disorders testing

BackgroundAccording to the American Academy of Audiology, a recommendation for frequency-modulation systems may be based upon performances on speech perception tests that do not include background noise. PurposeThe primary purpose of this study was to evaluate the presumption that non-speech recognition in noise test results are related to speech recognition in noise ability for a group of young adults. Research designPerformances on the non-speech recognition in noise tests included in the SCAN-3:A test battery were compared to speech recognition in noise performances as measured with the auditory figure ground subtest of the SCAN-3:A and the Hearing in Noise Test. Study sampleFifty-four young, native speakers of American English with normal pure-tone thresholds participated in the study. Data collection and analysisFor the purposes of this study, the SCAN-3:A raw scores were used. The Hearing in Noise Test was administered in a simulated soundfield environment under headphones. The Spearman rho statistic was used to determine the relationships between non-speech recognition in noise vs. speech recognition in noise test results. ResultsNo significant relationships were found between the auditory figure-ground results and any of the non-speech recognition in noise subtest performances. Modest but statistically significant relationships were found between the Hearing in Noise Test Composite scores vs. the competing words-directed ear and the time compressed sentences subtests of the SCAN-3:A. ConclusionOf the four non-speech recognition in noise subtests that were evaluated, only the competing words-directed ear and the time-compressed sentences performances were significantly correlated to the Composite scores of the Hearing in Noise Test. The results demonstrated a limited external validity for two of the four non-SRN tests for the determination of SRN ability.

Relation among the knowledge of teachers about hearing loss degree, technological devices and communication strategies.

To analyze the relations among the knowledge of teachers about hearing loss degree, technological devices, hearing aids (HA), cochlear implant (CI), frequency modulation system (FM), and communication strategies. Forty-two (42) teachers that taught students with hearing impairment participated in this study. This sample included 24 middle school teachers, 11 elementary school teachers, and 7 preschool teachers, whose taught in the second semester of the school year and in the first semester of the following year. The data was obtained through the Knowledge and Experience Questionnaire developed by Delgado-Pinheiro & Omote (2010). The questionnaire answers were categorized, and the frequency of occurrence was analyzed. Statistical analysis was performed using the chi-square test. There was a statistically significant difference between the answers which showed that the teachers do not know about the degree of hearing loss, but they modify the communication strategies to keep the attention of the students. In addition, the results also showed that teachers do not know the technological devices and communication strategies most appropriate for the student with hearing impairment. The results showed that teachers do not have sufficient knowledge about hearing impairment and as a result they modify their communication strategies for the student, even though they are unaware of the most appropriate communication strategies.

Impact of Personal Frequency Modulation Systems on Behavioral and Cortical Auditory Evoked Potential Measures of Auditory Processing and Classroom Listening in School-Aged Children with Auditory Processing Disorder.

Personal frequency modulation (FM) systems are often recommended for children diagnosed with auditory processing disorder (APD) to improve their listening environment in the classroom. Further evidence is required to support the continuation of this recommendation. To determine whether personal FM systems enhance auditory processing abilities and classroom listening in school-aged children with APD. Two baseline assessments separated by eight weeks were undertaken before a 20-week trial of bilateral personal FM in the classroom. The third assessment was completed immediately after the FM trial. A range of behavioral measures and speech-evoked cortical auditory evoked potentials (CAEPs) in quiet and in noise were used to assess auditory processing and FM outcomes. Perceived listening ability was assessed using the Listening Inventory for Education-United Kingdom version (LIFE-UK) questionnaire student and teacher versions, and a modified version of the LIFE-UK questionnaire for parents. Twenty-eight children aged 7-12 years were included in this intervention study. Of the 28 children, there were 22 males and six females. APD Tests scores and CAEP peak latencies and amplitudes were analyzed using repeated measures analysis of variance to determine whether results changed over the two baseline assessments and after the FM trial. The LIFE-UK was administered immediately before and after the FM trial. Student responses were analyzed using paired t-tests. Results are described for the (different) pre- and post-trial teacher versions of the LIFE-UK. Speech in spatial noise (SSN) scores improved by 13% on average when participants wore the FM system in the laboratory. Noise resulted in increased P1 and N2 latencies and reduced N2 amplitudes. The impact of noise on CAEP latencies and amplitudes was significantly reduced when participants wore the FM. Participants' LIFE-UK responses indicated significant improvements in their perceived listening after the FM trial. Most teachers (74%) reported the trial as successful, based on LIFE-UK ratings. Teachers' and parents' questionnaire ratings indicated good agreement regarding the outcomes of the FM trial. There was no change in compressed and reverberated words, masking level difference, and sustained attention scores across visits. Gaps in noise, dichotic digits test, and SSN (hard words) showed practice effects. Frequency pattern test and SSN easy word scores did not change between baseline visits, and improved significantly after the FM trial. CAEP N2 latencies and amplitudes changed significantly across visits; changes occurred across the baseline and the FM trial period. Personal FM systems produce immediate speech perception benefits and enhancement of speech-evoked cortical responses in noise in the laboratory. The 20-week FM trial produced significant improvements in behavioral measures of auditory processing and participants' perceptions of their listening skills. Teacher and parent questionnaires also indicated positive outcomes.

PR453: Non‐surgical periodontal therapy: use of piezoelectric generators with digital frequency modulation systems in the management of intraoperative comfort

PR453: Non‐surgical periodontal therapy: use of piezoelectric generators with digital frequency modulation systems in the management of intraoperative comfort

SmartHear: A Smartphone-Based Remote Microphone Hearing Assistive System Using Wireless Technologies

In this paper, we propose a new smartphone-based hearing assistive system (SmartHear) using wireless technologies for individuals with mild-to-moderate hearing loss (HL). Our system is a stigma-free implementation of the personal frequency modulation (FM) system for people with HL, with enhanced accessibility, affordability, and customization and extension potentials. The SmartHear system consists of a smartphone running a mobile application and a Bluetooth handset coupled with the smartphone. The voice of the speaker is picked up by the smartphone placed near the speaker and transmitted wirelessly to the Bluetooth handset placed near the listener for listening. The transmission of the voice signals over radio waves overcomes the reverberation and ambient noise effects, and thus, the listener can listen from a distance with better clarity and ease. Speech intelligibility experiments demonstrate the efficacy of the proposed SmartHear system, showing an average improvement of 0.2 speech intelligibility score (on the scale of 0–1) across four typical audiograms for mild-to-moderate HL and in four signal-to-noise ratio conditions. A user survey reveals the favorable user experience with SmartHear in various dimensions, as compared to the conventional FM system.

Verification Protocol for Signal Transparency Using the Cochlear Mini-Microphone 2+ and Digital Modulation Transmitter and Receiver with Cochlear Implants.

Guidelines established by the American Academy of Audiology (AAA) currently recommend behavioral testing when fitting frequency-modulated (FM) systems to individuals with cochlear implants (CIs). A protocol for completing electroacoustic measures on CI sound processors has not yet been established or validated when fitting either FM or digital-modulated (DM) systems, mini microphones, or mini microphones coupled to DM systems. In response, professionals have used or altered the AAA (2008) electroacoustic verification steps for fitting FM systems to hearing aids when fitting FM/DM systems, mini microphones, or mini microphones coupled to FM/DM systems to CI sound processors. The purpose of this research is to determine if the electroacoustic verification guidelines established by AAA (2008) for fitting FM systems to hearing aids are feasible and verifiable when fitting mini microphones and mini microphones coupled to DM systems to CI sound processors. Electroacoustic measures were conducted on 51 Cochlear Nucleus 6/CP910 sound processors, one Cochlear Wireless Mini Microphone 2+ (MM2+), and one Phonak DM System (one Roger Inspiro transmitter and one Roger X receiver) using an adapted AAA (2008) protocol (Nair et al, 2017). Phonak's recommended default receiver gain setting was used with the Roger X receiver and adjusted if necessary to achieve transparency. Transparency refers to when the signal output of the device is the same when coupled and when not coupled to remote microphone technology. Electroacoustic measures were conducted on 51 Cochlear Nucleus 6/CP910 sound processors. In this study, the 51 Cochlear Nucleus 6/CP910 sound processors were either streaming to the Cochlear MM2+ or streaming to the MM2+ coupled to a Phonak DM system. In a clinical setting, using the AAA (2008) protocol for electroacoustic measurements when fitting FM systems to hearing aids, electroacoustic measurements using various equipment (MM2+ and Phonak DM system) were performed on 51 Cochlear Nucleus 6/CP910 sound processors using the Audioscan Verifit to determine transparency and verify DM advantage, comparing speech inputs (65 dB SPL) in an effort to achieve equal outputs. If transparency was not achieved when the CI sound processor was streaming to the MM2+ coupled to the Phonak DM system at the default receiver gain, adjustments were made to the Roger X receiver's gain. The integrity of the signal was monitored with the manufacturer's monitor earphones. Using the AAA (2008) hearing aid protocol, when the Cochlear Nucleus 6/CP910 sound processor was streaming to the Cochlear MM2+, transparency was achieved for 50 of 51 CI sound processors. Again, using the AAA (2008) protocol when the Cochlear Nucleus 6/CP910 sound processor was streaming to the Cochlear MM2+ coupled to the Phonak DM system at Phonak's recommended default receiver gain, 28 sound processors achieved transparency. After the receiver gain was adjusted, the remaining 23 sound processors met transparency. Electroacoustic measurements and transparency can be achieved for CI sound processors coupled to either a MM2+ only or to a MM2+ and a DM system by adapting the AAA (2008) guidelines.

Electroacoustic verification of frequency modulation systems in cochlear implant users

IntroductionThe frequency modulation system is a device that helps to improve speech perception in noise and is considered the most beneficial approach to improve speech recognition in noise in cochlear implant users. According to guidelines, there is a need to perform a check before fitting the frequency modulation system. Although there are recommendations regarding the behavioral tests that should be performed at the fitting of the frequency modulation system to cochlear implant users, there are no published recommendations regarding the electroacoustic test that should be performed. ObjectivePerform and determine the validity of an electroacoustic verification test for frequency modulation systems coupled to different cochlear implant speech processors. MethodsThe sample included 40 participants between 5 and 18 year's users of four different models of speech processors. For the electroacoustic evaluation, we used the Audioscan Verifit device with the HA-1 coupler and the listening check devices corresponding to each speech processor model. In cases where the transparency was not achieved, a modification was made in the frequency modulation gain adjustment and we used the Brazilian version of the “Phrases in Noise Test” to evaluate the speech perception in competitive noise. ResultsIt was observed that there was transparency between the frequency modulation system and the cochlear implant in 85% of the participants evaluated. After adjusting the gain of the frequency modulation receiver in the other participants, the devices showed transparency when the electroacoustic verification test was repeated. It was also observed that patients demonstrated better performance in speech perception in noise after a new adjustment, that is, in these cases; the electroacoustic transparency caused behavioral transparency. ConclusionThe electroacoustic evaluation protocol suggested was effective in evaluation of transparency between the frequency modulation system and the cochlear implant. Performing the adjustment of the speech processor and the frequency modulation system gain are essential when fitting this device.