Frequency Modulation Receiver Research Articles

Chest-Worn Heart Rate Variability Monitor With a Self-Injection-Locked Oscillator Tag

This article presents a chest-worn device for monitoring the heart rate variability (HRV) of a person in motion without direct contact with the skin. The device operates at 5.8 GHz and mainly consists of a self-injection-locked oscillator (SILO) and a tag antenna. The device transmits the output signal of an SILO that is frequency-modulated (FM) by the Doppler effect of the physiological movement of the chest via the tag antenna to a remote FM receiver. Accordingly, the heartbeat is detected and the HRV can be estimated. The tag antenna comprises a circularly polarized ring slot antenna and a split-ring resonator (SRR) array in stack to enhance sensing directivity while reducing the moving clutter in the joint sensing and transmission process. For validation, an HRV monitoring system was developed, based on the proposed device, to detect the cardiac intervals of a wearer who performs various activities, including walking and running. The results thus obtained agree closely with electrocardiogram (ECG) measurements.

Design and FPGA Implementation of Digital Frequency Modulation Receiver

In this paper, we introduce the design of a digital frequency modulation receiver using FPGA. The main component in the design is digital phase locked loop (DPLL) which compensate any changes between the frequency and phase of the input modulated signal and the frequency and phase of numerically controlled oscillator. The input to the receiver is 8-bit represents the sampled discrete time signal from the analog modulated received frequency modulation signal. The receiver is designed using Xilinx system generator and implemented on the FPGA board (Xilinx Vitrex-7 XC7VX550t board), works with 350 MHz and consumes 120 mW.

Perancangan Trainer Komunikasi Receiver Frequency Modulation sebagai Media Pembelajaran untuk Teknik Elektro

On a Frequency Modulation (FM) receiver there is an interference caused which is usually due to the distance and strong signal from the FM transmitter carried to the FM receiver device. The system used PLL (Phase Loocked Loop) system on the oscillator. An oscillator is an electronic device that produces a voltage signal output. The use of oscillators as the carrier of the signal and the message signal produces waves with a certain frequency value, and has a frequency shift of 56,25KHz. The output of the FM receiver is a signal containing of the FM transmitter in the 88MHz-108MHz range. The signals received from the transmitter are short audio and sine signals, so they can be analyzed based on their waves in oscilloscopes and matlab experiments. In this trainer, there are tuners, IF amplifier, multiplexer demodulator, and digital counter frequency. The IC used is LA1260, LA3361, LB3500, LC7265. The result of making an FM receiver trainer get a satisfaction value of the practical test 80,12% based on aspects of media appearance, technical quality and usefulness. A device designed for UTM Electrical Engineering students as a trainer in FM telecommunications system learning medium practiced in the UTM Department of Electrical Engineering

Construction of a Mobile Frequency Modulation Transmitter

A Frequency Modulation (FM) transmitter is an electronic device that produces radio waves with the aid of an antenna. The transmitter generates radio frequency alternating current, that is applied to the antenna. When the antenna is excited by the alternating current, the antenna begins to radiate radio waves by varying the frequency of the radio signal. The transmitter is a Very High Frequency (VHF) Colpitts oscillator capable of transmitting sound to standard FM receiver fitted with a capacitor microphone which picks weak sound signals. This design was achieved using: transistors, resistors, inductors and capacitors. A transmission frequency of ± 5% 100 MHz was used and transmitted up to a distance of 5 metres. The testing of the transmitter was carried out by powering it using a 9 V DC battery and tuning a suitable FM receiver to the transmission frequency of the constructed transmitter. A transmission distance of 5 metres was achieved therefore making it possible to use the transmitter as a portable cordless microphone used for public address (P.A.) systems. The achieved fixed frequency of transmission 56.4 MHz, away from all other radio stations transmission frequencies. This gives the best range and with the least of interferences. With increased power, the range can easily be extended.

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.

Implementasi Sistem Komunikasi FM Pada Prototype Pendeteksi Dini Gempa

An earthquake is a vibration that occurs due to plates at the base of the earth rubbing against each other. An earthquake can have several impacts, namely material loss and loss of life and trauma for some people who feel it. This happens because people are not fast enough in getting information. Therefore we need an earthquake detection device that is relatively inexpensive. In this study designed a prototype for earthquake early detection using Frequency Modulation (FM) communication. The components of this system are Arduino Uno which functions as a microcontroller, SW-420 vibration sensor to detect vibrations, buzzer as the output of the SW-420 sensor in the form of sound and FM transmitter V2.0 which functions as a medium for transmitting radio frequency signals and sending sound from the buzzer . The level of vibration that indicates that an earthquake occurred namely 3-5 with a conversion of 5-10 SR. The system would have the ability to provide information in the form of sound received by a radio or FM receiver. The distance that can be emitted by the FM transmitter module V2.0 is 17.87 meter

Few-mode frequency-modulated LiDAR receivers.

We present a few-mode frequency-modulated receiver for light detection and ranging (LiDAR). We show that using a few-mode local oscillator (LO) with spatial modes at different frequencies at the receiver can significantly improve the performance of the LiDAR detection range. A preferred receiver architecture features LO modes with unequal frequency separations based on optical orthogonal codes (OOC) to allow range detection via cross correlation. The required signal-to-noise ratio (SNR) for the frequency-modulated continuous wave (FMCW) LiDAR decreases with the number of LO modes. This receiver can have a potential impact in the area of automotive LiDARs.

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.

Fitting and verification of frequency modulation systems on children with normal hearing.

Several recent investigations support the use of frequency modulation (FM) systems in children with normal hearing and auditory processing or listening disorders such as those diagnosed with auditory processing disorders, autism spectrum disorders, attention-deficit hyperactivity disorder, Friedreich ataxia, and dyslexia. The American Academy of Audiology (AAA) published suggested procedures, but these guidelines do not cite research evidence to support the validity of the recommended procedures for fitting and verifying nonoccluding open-ear FM systems on children with normal hearing. Documenting the validity of these fitting procedures is critical to maximize the potential FM-system benefit in the above-mentioned populations of children with normal hearing and those with auditory-listening problems. The primary goal of this investigation was to determine the validity of the AAA real-ear approach to fitting FM systems on children with normal hearing. The secondary goal of this study was to examine speech-recognition performance in noise and loudness ratings without and with FM systems in children with normal hearing sensitivity. A two-group, cross-sectional design was used in the present study. Twenty-six typically functioning children, ages 5-12 yr, with normal hearing sensitivity participated in the study. Participants used a nonoccluding open-ear FM receiver during laboratory-based testing. Participants completed three laboratory tests: (1) real-ear measures, (2) speech recognition performance in noise, and (3) loudness ratings. Four real-ear measures were conducted to (1) verify that measured output met prescribed-gain targets across the 1000-4000 Hz frequency range for speech stimuli, (2) confirm that the FM-receiver volume did not exceed predicted uncomfortable loudness levels, and (3 and 4) measure changes to the real-ear unaided response when placing the FM receiver in the child's ear. After completion of the fitting, speech recognition in noise at a -5 signal-to-noise ratio and loudness ratings at a +5 signal-to-noise ratio were measured in four conditions: (1) no FM system, (2) FM receiver on the right ear, (3) FM receiver on the left ear, and (4) bilateral FM system. The results of this study suggested that the slightly modified AAA real-ear measurement procedures resulted in a valid fitting of one FM system on children with normal hearing. On average, prescriptive targets were met for 1000, 2000, 3000, and 4000 Hz within 3 dB, and maximum output of the FM system never exceeded and was significantly lower than predicted uncomfortable loudness levels for the children. There was a minimal change in the real-ear unaided response when the open-ear FM receiver was placed into the ear. Use of the FM system on one or both ears resulted in significantly better speech recognition in noise relative to a no-FM condition, and the unilateral and bilateral FM receivers resulted in a comfortably loud signal when listening in background noise. Real-ear measures are critical for obtaining an appropriate fit of an FM system on children with normal hearing.

Electromagnetic versus Electrical Coupling of Personal Frequency Modulation (FM) Receivers to Cochlear Implant Sound Processors

Previous research has suggested that electrically coupled frequency modulation (FM) systems substantially improved speech-recognition performance in noise in individuals with cochlear implants (CIs). However, there is limited evidence to support the use of electromagnetically coupled (neck loop) FM receivers with contemporary CI sound processors containing telecoils. The primary goal of this study was to compare speech-recognition performance in noise and subjective ratings of adolescents and adults using one of three contemporary CI sound processors coupled to electromagnetically and electrically coupled FM receivers from Oticon. A repeated-measures design was used to compare speech-recognition performance in noise and subjective ratings without and with the FM systems across three test sessions (Experiment 1) and to compare performance at different FM-gain settings (Experiment 2). Descriptive statistics were used in Experiment 3 to describe output differences measured through a CI sound processor. Experiment 1 included nine adolescents or adults with unilateral or bilateral Advanced Bionics Harmony (n = 3), Cochlear Nucleus 5 (n = 3), and MED-EL OPUS 2 (n = 3) CI sound processors. In Experiment 2, seven of the original nine participants were tested. In Experiment 3, electroacoustic output was measured from a Nucleus 5 sound processor when coupled to the electromagnetically coupled Oticon Arc neck loop and electrically coupled Oticon R2. In Experiment 1, participants completed a field trial with each FM receiver and three test sessions that included speech-recognition performance in noise and a subjective rating scale. In Experiment 2, participants were tested in three receiver-gain conditions. Results in both experiments were analyzed using repeated-measures analysis of variance. Experiment 3 involved electroacoustic-test measures to determine the monitor-earphone output of the CI alone and CI coupled to the two FM receivers. The results in Experiment 1 suggested that both FM receivers provided significantly better speech-recognition performance in noise than the CI alone; however, the electromagnetically coupled receiver provided significantly better speech-recognition performance in noise and better ratings in some situations than the electrically coupled receiver when set to the same gain. In Experiment 2, the primary analysis suggested significantly better speech-recognition performance in noise for the neck-loop versus electrically coupled receiver, but a second analysis, using the best performance across gain settings for each device, revealed no significant differences between the two FM receivers. Experiment 3 revealed monitor-earphone output differences in the Nucleus 5 sound processor for the two FM receivers when set to the +8 setting used in Experiment 1 but equal output when the electrically coupled device was set to a +16 gain setting and the electromagnetically coupled device was set to the +8 gain setting. Individuals with contemporary sound processors may show more favorable speech-recognition performance in noise electromagnetically coupled FM systems (i.e., Oticon Arc), which is most likely related to the input processing and signal processing pathway within the CI sound processor for direct input versus telecoil input. Further research is warranted to replicate these findings with a larger sample size and to develop and validate a more objective approach to fitting FM systems to CI sound processors.

Better Speech Recognition with Digital RF System in Study of Cochlear Implants

Better Speech Recognition with Digital RF System in Study of Cochlear Implants

Speech Recognition and Subjective Perceptions of Neck-Loop FM Receivers With Cochlear Implants

The goal of this investigation was to determine the potential benefit of using electromagnetically coupled frequency modulation (FM) neck-loop receivers to address common communication difficulties of adults and adolescents with cochlear implants (CIs). Fourteen participants with CIs used the neck-loop FM receiver for a trial period and participated in pre- and post trial sessions consisting of speech-recognition-in-noise measures with and without the FM system and a subjective rating scale. Most participants also recorded their experiences during the FM-system trial period in a journal. The results suggested significantly improved speech recognition in noise with the neck-loop FM system before and after the trial period, with no changes in performance between test sessions. On average, the rating scale and journals revealed improvements with the FM system, relative to the CI alone, in noisy environments or situations at a distance from the primary talker or sound source. The results of the study suggest that neck-loop FM receivers significantly improved speech recognition in noise and everyday listening challenges of people using the CIs in 2 separate test sessions. Additional research is warranted for other types of neck-loop receivers and CI sound processors.

Maximizing Parallel Testing in an FM Receiver

High volume production environments create great challenges for production testing and verification of Radio Frequency (RF) devices. In this environment, much emphasis is put on parallel testing, or the ability to test multiple devices at the same time using a single tester. In order for this parallelism to become a reality, there is a need for production RF tests to be simplified and reduced to requiring only the simplest test stimulus and analysis. In this paper, we present a new method of measuring the performance of a Frequency Modulation (FM) receiver that requires only a continuous wave signal input in order to eliminate the more costly Signal-to-Noise Ratio test. Using this new technique we will then demonstrate how simplifying this test and adding frequency diversity enables testing of up to 8 devices in parallel using a single tester.

A Telecontrol Navigation System for Bio-robot

A telecontrol navigation system for bio-robot is developed,which is applicable to the navigation control of rats by stimulating some particular brain areas.The system basically consists of two parts,i.e.,wireless parameters transmitter device(WPTD) and implantable neural stimulation system(INSS).The WPTD contains a single-chip microcomputer (C8051F330),a wireless frequency modulation(FM) transmitter chip(QN8027) and power amplifier(PA) circuits.The INSS includes a C8051F330,a wireless FM receiver chip(QN8025),analog switches,and implantable electrodes.The INSS is fabricated of surface mount devices(SMD) with the dimension of 20 mm×15 mm×3 mm,weight of 6 g(including a rechargeable lithium battery,3 g).Lateral medial forebrain bundle(MFB) and ventral posterlateral thalamic nucleus(VPL) are selected as the brain sites to be stimulated,and each brain site is implanted into a pair of electrodes.Each pair of electrodes as one channel is connected with INSS,so that WPTD can regulate the signal parameters of the neural stimulation in each channel in real time.Experiments indicate that the current stimulation of MFB with proper parameters can drives the rat to move forward as virtual reward,while the current stimulation of VPL with proper parameters can cause the rat to turn left or right.

Speech Perception in Noise in Normally Hearing Children: Does Binaural Frequency Modulated Fitting Provide More Benefit than Monaural Frequency Modulated Fitting?

The aim of the present study was to compare the benefit of monaural versus binaural ear-level frequency modulated (FM) fitting on speech perception in noise in children with normal hearing. Reception threshold for sentences (RTS) was measured in no-FM, monaural FM, and binaural FM conditions in 22 normally developing children with bilateral normal hearing, aged 8 to 9 years old. Data were gathered using the Pediatric Malay Hearing in Noise Test (P-MyHINT) with speech presented from front and multi-talker babble presented from 90°, 180°, 270° azimuths in a sound treated booth. The results revealed that the use of either monaural or binaural ear level FM receivers provided significantly better mean RTSs than the no-FM condition (P<0.001). However, binaural FM did not produce a significantly greater benefit in mean RTS than monaural fitting. The benefit of binaural over monaural FM varies across individuals; while binaural fitting provided better RTSs in about 50% of study subjects, there were those in whom binaural fitting resulted in either deterioration or no additional improvement compared to monaural FM fitting.The present study suggests that the use of monaural ear-level FM receivers in children with normal hearing might provide similar benefit as binaural use. Individual subjects’ variations of binaural FM benefit over monaural FM suggests that the decision to employ monaural or binaural fitting should be individualized. It should be noted however, that the current study recruits typically developing normal hearing children. Future studies involving normal hearing children with high risk of having difficulty listening in noise is indicated to see if similar findings are obtained.

Interfacing FM Systems with Implantable Hearing Devices

Cochlear implant recipients can reduce the challenges they encounter in noisy environments through the use of a remote microphone. Although there are numerous options for delivering the signal from the frequency modulated (FM) transmitter worn by the speaker to the FM receiver coupled to the implant, several have now been verified through research as viable, beneficial arrangements. Recommendations for the settings on the implant include mixing ratio and settings on the FM receivers (i.e., FM advantage). Because coupling of the FM system with the implant cannot be tested with traditional electroacoustic methods, behavioral verification using speech recognition in noise with the implant alone and with the implant plus the FM system is necessary. A variety of resources are available for the audiologist to consult for the specific components, start sequence of switches, and verification protocols. Resources can be found through manufacturer and professional association Web sites.

Evaluation of Speech Recognition in Noise with Cochlear Implants and Dynamic FM

Use of personal frequency-modulated (FM) systems significantly improves speech recognition in noise for users of cochlear implants (CIs). Previous studies have shown that the most appropriate gain setting on the FM receiver may vary based on the listening situation and the manufacturer of the CI system. Unlike traditional FM systems with fixed-gain settings, Dynamic FM automatically varies the gain of the FM receiver with changes in the ambient noise level. There are no published reports describing the benefits of Dynamic FM use for CI recipients or how Dynamic FM performance varies as a function of CI manufacturer. To evaluate speech recognition of Advanced Bionics Corporation or Cochlear Corporation CI recipients using Dynamic FM vs. a traditional FM system and to examine the effects of Autosensitivity on the FM performance of Cochlear Corporation recipients. A two-group repeated-measures design. Participants were assigned to a group according to their type of CI. Twenty-five subjects, ranging in age from 8 to 82 years, met the inclusion criteria for one or more of the experiments. Thirteen subjects used Advanced Bionics Corporation, and 12 used Cochlear Corporation implants. Speech recognition was assessed while subjects used traditional, fixed-gain FM systems and Dynamic FM systems. In Experiments 1 and 2, speech recognition was evaluated with a traditional, fixed-gain FM system and a Dynamic FM system using the Hearing in Noise Test sentences in quiet and in classroom noise. A repeated-measures analysis of variance (ANOVA) was used to evaluate effects of CI manufacturer (Advanced Bionics and Cochlear Corporation), type of FM system (traditional and dynamic), noise level, and use of Autosensitivity for users of Cochlear Corporation implants. Experiment 3 determined the effects of Autosensitivity on speech recognition of Cochlear Corporation implant recipients when listening through the speech processor microphone with the FM system muted. A repeated-measures ANOVA was used to examine the effects of signal-to-noise ratio and Autosensitivity. In Experiment 1, use of Dynamic FM resulted in better speech recognition in noise for Advanced Bionics recipients relative to traditional FM at noise levels of 65, 70, and 75 dB SPL. Advanced Bionics recipients obtained better speech recognition in noise with FM use when compared to Cochlear Corporation recipients. When Autosensitivity was enabled in Experiment 2, the performance of Cochlear Corporation recipients was equivalent to that of Advanced Bionics recipients, and Dynamic FM was significantly better than traditional FM. Results of Experiment 3 indicate that use of Autosensitivity improves speech recognition in noise of signals directed to the speech processor relative to no Autosensitivity. Dynamic FM should be considered for use with persons with CIs to improve speech recognition in noise. At default CI settings, FM performance is better for Advanced Bionics recipients when compared to Cochlear Corporation recipients, but use of Autosensitivity by Cochlear Corporation users results in equivalent group performance.

Optimizing The Benefit of Sound Processors Coupled to Personal FM Systems

Use of personal frequency modulated (FM) systems significantly improves speech recognition in noise for users of cochlear implants (CI). There are, however, a number of adjustable parameters of the cochlear implant and FM receiver that may affect performance and benefit, and there is limited evidence to guide audiologists in optimizing these parameters. This study examined the effect of two sound processor audio-mixing ratios (30/70 and 50/50) on speech recognition and functional benefit for adults with CIs using the Advanced Bionics Auria sound processors. Fully-repeated repeated measures experimental design. Each subject participated in every speech-recognition condition in the study, and qualitative data was collected with subject questionnaires. Twelve adults using Advanced Bionics Auria sound processors. Participants had greater than 20% correct speech recognition on consonant-nucleus-consonant (CNC) monosyllabic words in quiet and had used their CIs for at least six months. Performance was assessed at two audio-mixing ratios (30/70 and 50/50). For the 50/50 mixing ratio, equal emphasis is placed on the signals from the sound processor and the FM system. For the 30/70 mixing ratio, the signal from the microphone of the sound processor is attenuated by 10 dB. Speech recognition was assessed at two audio-mixing ratios (30/70 and 50/50) in quiet (35 and 50 dB HL) and in noise (+5 signal-to-noise ratio) with and without the personal FM system. After two weeks of using each audio-mixing ratio, the participants completed subjective questionnaires. Study results suggested that use of a personal FM system resulted in significant improvements in speech recognition in quiet at low-presentation levels, speech recognition in noise, and perceived benefit in noise. Use of the 30/70 mixing ratio resulted in significantly poorer speech recognition for low-level speech that was not directed to the FM transmitter. There was no significant difference in speech recognition in noise or functional benefit between the two audio-mixing ratios. Use of a 50/50 audio-mixing ratio is recommended for optimal performance with an FM system in quiet and noisy listening situations.

Selecting the Optimal FM System for Children With Cochlear Implants

Children who use cochlear implants experience significant difficulty hearing speech in the presence of background noise, such as in the classroom. To address these difficulties, audiologists often recommend frequency-modulated (FM) systems for children with cochlear implants. The purpose of this article is to examine current empirical research in the area of FM systems and cochlear implants. Discussion topics will include selecting the optimal type of FM receiver, benefits of binaural FM-system input, importance of DAI receiver-gain settings, and effects of speech-processor programming on speech recognition. FM systems significantly improve the signal-to-noise ratio at the child's ear through the use of three types of FM receivers: mounted speakers, desktop speakers, or direct-audio input (DAI). This discussion will aid audiologists in making evidence-based recommendations for children using cochlear implants and FM systems.

Electroacoustic Evaluation of Frequency-Modulated Receivers Interfaced With Personal Hearing Aids

The purpose of this study was to compare the electroacoustic outputs of frequency-modulated (FM) systems coupled to hearing aids. Electroacoustic performance of FM systems coupled to hearing aids was determined for 3 FM receivers: body-worn with neck loop, ear-level nonprogrammable, and ear-level programmable. Systems were evaluated using the FM-advantage approach suggested by the American Speech-Language-Hearing Association's "Guidelines for Fitting and Monitoring FM Systems" (2002). Output differences between the hearing aid and FM system were examined for typical input levels with a complex signal to verify an FM advantage and for high-input levels with a pure-tone signal to confirm similarity in maximum output. Measurements from the FM receivers with neck loops showed significant low-frequency reduction and the most variable performance of the 3 types of systems. Less variable measurements were obtained with the ear-level FM receivers, and programmable FM receivers allowed for the most flexibility in obtaining an FM advantage. Findings of variability may be related to the type of system and the compression characteristics of the devices. Findings of great variability in electroacoustic performance of all systems support the need for electroacoustic evaluation, particularly when observing the effects of various settings on new technology.