Measures Of Frequency Selectivity Research Articles

Extensive frequency selective measurements of radiofrequency fields in outdoor environments performed with a novel mobile monitoring system

A novel, car based, measuring system for estimation of general public outdoor exposure to radiofrequency fields (RF) has been developed. The system enables fast, large area, isotropic spectral measurements with a bandwidth covering the frequency range of 30 MHz to 3 GHz. Measurements have shown that complete mapping of a town with 15000 inhabitants and a path length of 115 km is possible to perform within 1 day. The measured areas were chosen to represent typical rural, urban and city areas of Sweden. The data sets consist of more than 70000 measurements. All measurements were performed during the daytime. The median power density was 16 µW/m(2) in rural areas, 270 µW/m(2) in urban areas, and 2400 µW/m(2) in city areas. In urban and city areas, base stations for mobile phones were clearly the dominating sources of exposure.

Acquisition of auditory profiles for good and impaired hearing

Objective: The aim of this study was to develop a user-friendly way of measuring patients’ threshold and supra-threshold hearing, with potential for application in clinical research. The end-product of these tests is a graphical profile summarizing absolute threshold, frequency selectivity, and compression characteristics across a spectrum of frequencies (0.25–6 kHz). Design: A battery of three psychophysical hearing tests consisted of measures of absolute threshold, frequency selectivity, and compression. An automated, cued, single-interval, adaptive tracking procedure was employed. The tests results were collated and used to generate a readily visualized ‘profile’ for each listener. Study sample: Participants were 83 adults (57 impaired-hearing and 26 good-hearing, age 20–75 years). Results: Listeners tolerated the tests well. Single-ear profiles were obtained in an average of 74 minutes testing time (range 46–120 minutes). The variability of individual measurements was low. Substantial differences between normal and impaired listeners and also among the impaired listeners were observed. Qualitative differences in compression and frequency-selectivity were seen that could not be predicted by threshold measurements alone. Conclusions: The hearing profiles are informative with respect to supra-threshold hearing performance and the information is easily accessible through the graphical display. Further development is required for routine use in a clinical context.

Spectrotemporal Modulation Sensitivity as a Predictor of Speech Intelligibility for Hearing-Impaired Listeners

A model that can accurately predict speech intelligibility for a given hearing-impaired (HI) listener would be an important tool for hearing-aid fitting or hearing-aid algorithm development. Existing speech-intelligibility models do not incorporate variability in suprathreshold deficits that are not well predicted by classical audiometric measures. One possible approach to the incorporation of such deficits is to base intelligibility predictions on sensitivity to simultaneously spectrally and temporally modulated signals. The likelihood of success of this approach was evaluated by comparing estimates of spectrotemporal modulation (STM) sensitivity to speech intelligibility and to psychoacoustic estimates of frequency selectivity and temporal fine-structure (TFS) sensitivity across a group of HI listeners. The minimum modulation depth required to detect STM applied to an 86 dB SPL four-octave noise carrier was measured for combinations of temporal modulation rate (4, 12, or 32 Hz) and spectral modulation density (0.5, 1, 2, or 4 cycles/octave). STM sensitivity estimates for individual HI listeners were compared to estimates of frequency selectivity (measured using the notched-noise method at 500, 1000, 2000, and 4000 Hz), TFS processing ability (2 Hz frequency-modulation detection thresholds for 500, 1000, 2000, and 4000 Hz carriers) and sentence intelligibility in noise (at a 0 dB signal-to-noise ratio) that were measured for the same listeners in a separate study. Eight normal-hearing (NH) listeners and 12 listeners with a diagnosis of bilateral sensorineural hearing loss participated. STM sensitivity was compared between NH and HI listener groups using a repeated-measures analysis of variance. A stepwise regression analysis compared STM sensitivity for individual HI listeners to audiometric thresholds, age, and measures of frequency selectivity and TFS processing ability. A second stepwise regression analysis compared speech intelligibility to STM sensitivity and the audiogram-based Speech Intelligibility Index. STM detection thresholds were elevated for the HI listeners, but only for low rates and high densities. STM sensitivity for individual HI listeners was well predicted by a combination of estimates of frequency selectivity at 4000 Hz and TFS sensitivity at 500 Hz but was unrelated to audiometric thresholds. STM sensitivity accounted for an additional 40% of the variance in speech intelligibility beyond the 40% accounted for by the audibility-based Speech Intelligibility Index. Impaired STM sensitivity likely results from a combination of a reduced ability to resolve spectral peaks and a reduced ability to use TFS information to follow spectral-peak movements. Combining STM sensitivity estimates with audiometric threshold measures for individual HI listeners provided a more accurate prediction of speech intelligibility than audiometric measures alone. These results suggest a significant likelihood of success for an STM-based model of speech intelligibility for HI listeners.

Suprathreshold Auditory Processing and Speech Perception in Noise: Hearing-Impaired and Normal-Hearing Listeners

It is widely believed that suprathreshold distortions in auditory processing contribute to the speech recognition deficits experienced by hearing-impaired (HI) listeners in noise. Damage to outer hair cells and attendant reductions in peripheral compression and frequency selectivity may contribute to these deficits. In addition, reduced access to temporal fine structure (TFS) information in the speech waveform may play a role. To examine how measures of peripheral compression, frequency selectivity, and TFS sensitivity relate to speech recognition performance by HI listeners. To determine whether distortions in processing reflected by these psychoacoustic measures are more closely associated with speech deficits in steady-state or modulated noise. Normal-hearing (NH) and HI listeners were tested on tasks examining frequency selectivity (notched-noise task), peripheral compression (temporal masking curve task), and sensitivity to TFS information (frequency modulation [FM] detection task) in the presence of random amplitude modulation. Performance was tested at 500, 1000, 2000, and 4000 Hz at several presentation levels. The same listeners were tested on sentence recognition in steady-state and modulated noise at several signal-to-noise ratios. Ten NH and 18 HI listeners were tested. NH listeners ranged in age from 36 to 80 yr (M = 57.6). For HI listeners, ages ranged from 58 to 87 yr (M = 71.8). Scores on the FM detection task at 1 and 2 kHz were significantly correlated with speech scores in both noise conditions. Frequency selectivity and compression measures were not as clearly associated with speech performance. Speech Intelligibility Index (SII) analyses indicated only small differences in speech audibility across subjects for each signal-to-noise ratio (SNR) condition that would predict differences in speech scores no greater than 10% at a given SNR. Actual speech scores varied by as much as 80% across subjects. The results suggest that distorted processing of audible speech cues was a primary factor accounting for differences in speech scores across subjects and that reduced ability to use TFS cues may be an important component of this distortion. The influence of TFS cues on speech scores was comparable in steady-state and modulated noise. Speech recognition was not related to audibility, represented by the SII, once high-frequency sensitivity differences across subjects (beginning at 5 kHz) were removed statistically. This might indicate that high-frequency hearing loss is associated with distortions in processing in lower-frequency regions.

Understanding Excessive SNR Loss in Hearing-Impaired Listeners

Traditional audiometric measures, such as pure-tone thresholds or unaided word-recognition in quiet, appear to be of marginal use in predicting speech understanding by hearing-impaired (HI) individuals in background noise with or without amplification. Suprathreshold measures of auditory function (tolerance of noise, temporal and frequency resolution) appear to contribute more to success with amplification and may describe more effectively the distortion component of hearing. However, these measures are not typically measured clinically. When combined with measures of audibility, suprathreshold measures of auditory distortion may provide a much more complete understanding of speech deficits in noise by HI individuals. The primary goal of this study was to investigate the relationship among measures of speech recognition in noise, frequency selectivity, temporal acuity, modulation masking release, and informational masking in adult and elderly patients with sensorineural hearing loss to determine whether peripheral distortion for suprathreshold sounds contributes to the varied outcomes experienced by patients with sensorineural hearing loss listening to speech in noise. A correlational study. Twenty-seven patients with sensorineural hearing loss and four adults with normal hearing were enrolled in the study. The data were collected in a sound attenuated test booth. For speech testing, subjects' verbal responses were scored by the experimenter and entered into a custom computer program. For frequency selectivity and temporal acuity measures, subject responses were recorded via a touch screen. Simple correlation, step-wise multiple linear regression analyses and a repeated analysis of variance were performed. Results showed that the signal-to-noise ratio (SNR) loss could only be partially predicted by a listener's thresholds or audibility measures such as the Speech Intelligibility Index (SII). Correlations between SII and SNR loss were higher using the Hearing-in-Noise Test (HINT) than the Quick Speech-in-Noise test (QSIN) with the SII accounting for 71% of the variance in SNR loss for the HINT but only 49% for the QSIN. However, listener age and the addition of suprathreshold measures improved the prediction of SNR loss using the QSIN, accounting for nearly 71% of the variance. Two standard clinical speech-in-noise tests, QSIN and HINT, were used in this study to obtain a measure of SNR loss. When administered clinically, the QSIN appears to be less redundant with hearing thresholds than the HINT and is a better indicator of a patient's suprathreshold deficit and its impact on understanding speech in noise. Additional factors related to aging, spectral resolution, and, to a lesser extent, temporal resolution improved the ability to predict SNR loss measured with the QSIN. For the HINT, a listener's audibility and age were the only two significant factors. For both QSIN and HINT, roughly 25-30% of the variance in individual differences in SNR loss (i.e., the dB difference in SNR between an individual HI listener and a control group of NH listeners at a specified performance level, usually 50% word or sentence recognition) remained unexplained, suggesting the need for additional measures of suprathreshold acuity (e.g., sensitivity to temporal fine structure) or cognitive function (e.g., memory and attention) to further improve the ability to understand individual variability in SNR loss.

Research on Frequency Conversion ＆ Selective Measurement and Error Correction Algorithms in Grounding Characteristics Measuring System

The paper concerns algorithms error and parameters correction technology of frequency conversion＆selective measurement in grounding characteristics measuring system. It analyzes estimation method of signal amplitude phase based on Fourier transform, calculates the sensitive degree of the method to frequency error, and also presents several major parameters for the algorithm, including sampling rate, data length and selection condition of frequency resolution in order to meet the high precision measurement requirements. Furthermore, the paper analyzes correction algorithm of amplitude and phase error caused by unknown nonlinearity of circuit during the practical measurement.

Evaluating the effects of olivocochlear feedback on psychophysical measures of frequency selectivity

Frequency selectivity was evaluated under two conditions designed to assess the influence of a "precursor" stimulus on auditory filter bandwidths. The standard condition consisted of a short masker, immediately followed by a short signal. The precursor condition was identical except a 100-ms sinusoid at the signal frequency (i.e., the precursor) was presented before the masker. The standard and precursor conditions were compared for measurements of psychophysical tuning curves (PTCs), and notched noise tuning characteristics. Estimates of frequency selectivity were significantly broader in the precursor condition. In the second experiment, PTCs in the standard and precursor conditions were simulated to evaluate the influence of the precursor on PTC bandwidth. The model was designed to account for the influence of additivity of masking between the masker and precursor. Model simulations were able to qualitatively account for the perceptual data when outer hair cell gain of the model was reduced in the precursor condition. These findings suggest that the precursor may have reduced cochlear gain, in addition to producing additivity of masking. This reduction in gain may be mediated by the medial olivocochlear reflex.

Stream segregation of simultaneous harmonic sounds in normal and impaired hearing

Many everyday situations involve hearing out harmonic sounds, such as voiced speech or musical notes, and following them over time in the presence of other harmonic sounds. Despite decades of research on pitch perception, it remains unclear whether the ability to hear out the pitch of one harmonic sound in the presence of others is limited by peripheral frequency selectivity or by other factors, such as phase-locking to the temporal waveform of sounds. In this study a direct test of the role of frequency selectivity was undertaken by examining the relationship between measures of frequency selectivity and measures of performance in pitch- and melody-discrimination tasks in normal-hearing and hearing-impaired listeners. Preliminary data suggest a relationship between auditory-filter bandwidths and the amount of interference produced by a harmonic-complex masker. However, some aspects of the results indicate that factors other than frequency selectivity also play an important role, particularly in the complex tasks involving melody discrimination. [Work was supported by NIH grant R01DC05216; subject recruitment was facilitated by Starkey Laboratories, Inc.]

Time-efficient measures of auditory frequency selectivity

Objective: The objective of this study was to compare two recently proposed methods for fast measurements of psychophysical tuning curves (fast-PTCs) in terms of resulting tuning curve features and training effects. Design: Fast-PTCs with swept-noise (SN) and gated-noise (GN) maskers were measured at signal frequencies of 500, 1000, 2000, and 4000 Hz. The effect of amplitude modulating the signal in the GN condition was evaluated. Two PTC runs were obtained for each condition to assess training effects. Study sample: Eight normally-hearing young adults participated in the study. Results: The SN and GN methods resulted in similar estimates of frequency selectivity when training effects were considered. Amplitude modulating the tone in the GN method reduced the effect of training. On average, SN-PTCs were most repeatable compared to the two other methods and they were not affected by training. Estimation of the shift in the PTC tip frequency was not affected by the measurement method or training effects. Fast-PTC methods resulted in similar estimates of tuning as compared to published notched-noise data. Conclusions: The SN method and the GN procedure with amplitude modulated signals allowed for time-efficient estimation of frequency selectivity that was unaffected by training.

Measurements for assessing the exposure from 3G femtocells

Femtocells are low-power access points, which combine mobile and broadband technologies. The main operation of a femtocell is to function as a miniature base station unit in an indoor environment and to connect to the operator's network through a broadband phone line or a coaxial cable line. This study provides the first experimental measurements and results in Greece for the assessment of exposure to a femtocell access point (FAP) indoors. Using a mobile handset with the appropriate software, power level measurements of the transmitted (Tx) and the received by the mobile handset signal were performed in two different and typical (home and office) environments. Moreover, radiofrequency electric field strength and frequency selective measurements with a radiation meter (SRM-3000) were carried out in the proximity of the FAP installation point. The cumulative distribution functions of the Tx power at most cases (except one) show that in 90% of all points the power of the mobile phone was lower by at least 7 dB during FAP operation. At a distance of ∼1 m from the FAP (in its main beam), power flux density measurements show that there is very little difference between the two situations (FAP ON and OFF). As a conclusion, the use of femtocells indoors improves reception quality, reduces the Tx power of the user's mobile terminal and results in an indiscernible increase of the electromagnetic field in front of the unit, at values that are extremely low compared with reference levels of exposure guidelines.

The effects of age and cochlear hearing loss on temporal fine structure sensitivity, frequency selectivity, and speech reception in noise

Temporal fine structure (TFS) sensitivity, frequency selectivity, and speech reception in noise were measured for young normal-hearing (NHY), old normal-hearing (NHO), and hearing-impaired (HI) subjects. Two measures of TFS sensitivity were used: the "TFS-LF test" (interaural phase difference discrimination) and the "TFS2 test" (discrimination of harmonic and frequency-shifted tones). These measures were not significantly correlated with frequency selectivity (after partialing out the effect of audiometric threshold), suggesting that insensitivity to TFS cannot be wholly explained by a broadening of auditory filters. The results of the two tests of TFS sensitivity were significantly but modestly correlated, suggesting that performance of the tests may be partly influenced by different factors. The NHO group performed significantly more poorly than the NHY group for both measures of TFS sensitivity, but not frequency selectivity, suggesting that TFS sensitivity declines with age in the absence of elevated audiometric thresholds or broadened auditory filters. When the effect of mean audiometric threshold was partialed out, speech reception thresholds in modulated noise were correlated with TFS2 scores, but not measures of frequency selectivity or TFS-LF test scores, suggesting that a reduction in sensitivity to TFS can partly account for the speech perception difficulties experienced by hearing-impaired subjects.

Otoacoustic emission delays as a probe to measure cochlear tuning: Comparative validations.

The ear is not only sensitive to sound but selective as well: Tonotopic tuning of the inner ear provides a means to resolve incoming spectral information. Measurements of frequency selectivity have traditionally relied upon either subjective psychophysical or objective (but invasive) physiological approaches. Sounds emitted from a healthy ear, known as otoacoustic emissions (OAEs), have been proposed to both objectively and non‐invasively estimate peripheral auditory tuning. Despite diverse inner‐ear morphological variation across animals, OAEs are a universal feature and correlate well to an animal’s range of active hearing. Recent studies focusing on emission delays in response to a single stimulus frequency (SFOAEs), conducted systematically across species in a variety of classes (mammals, aves, reptiles, and amphibians), support predictions relating emissions and tuning. Longer SFOAE delays presumably reflect the sharper tuning associated with resonant build‐up time of the underlying auditory filters. Differences in tuning estimated from OAEs appear generally congruous with known anatomical and functional considerations: Larger sensory organs (i.e., more “filters”) with smaller ranges of audition exhibit sharper tuning. Comparisons made both broadly (inter‐class) and within phylogenetically‐matched groups (intra‐family) indicate that SFOAE delays in humans are longer than any other species so far examined, suggestive of exceptionally sharper tuning.

Estimation of Hepatic Proton-Density Fat Fraction by Using MR Imaging at 3.0 T

To compare the accuracy of several magnetic resonance (MR) imaging-based methods for hepatic proton-density fat fraction (FF) estimation at 3.0 T, with spectroscopy as the reference technique. This prospective study was institutional review board approved and HIPAA compliant. Informed consent was obtained. One hundred sixty-three subjects (39 with known hepatic steatosis, 110 with steatosis risk factors, 14 without risk factors) underwent proton MR spectroscopy and non-T1-weighted gradient-echo MR imaging of the liver. At spectroscopy, the reference FF was determined from frequency-selective measurements of fat and water proton densities. At imaging, FF was calculated by using two-, three-, or six-echo methods, with single-frequency and multifrequency fat signal modeling. The three- and six-echo methods corrected for T2*; the two-echo methods did not. For each imaging method, the fat estimation accuracy was assessed by using linear regression between the imaging FF and spectroscopic FF. Binary classification accuracy of imaging was assessed at four reference spectroscopic thresholds (0.04, 0.06, 0.08, and 0.10 FF). Regression intercept of two-, three-, and six-echo methods were -0.0211, 0.0087, and -0.0062 (P <.001 for all three) without multifrequency modeling and -0.0237 (P <.001), 0.0022, and -0.0007 with multifrequency modeling, respectively. Regression slope of two-, three-, and six-echo methods were 0.8522, 0.8528, and 0.7544 (P <.001 for all three) without multifrequency modeling and 0.9994, 0.9775, and 0.9821 with multifrequency modeling, respectively. Significant deviation of intercept and slope from 0 and 1, respectively, indicated systematic error. Classification accuracy was 82.2%-90.1%, 93.9%-96.3%, and 83.4%-89.6% for two-, three-, and six-echo methods without multifrequency modeling and 88.3%-92.0%, 95.1%-96.3%, and 94.5%-96.3% with multifrequency modeling, respectively, depending on the FF threshold. T2*-corrected (three- and six-echo) multifrequency imaging methods had the overall highest FF estimation and classification accuracy. Among methods without multifrequency modeling, the T2-corrected three-echo method had the highest accuracy. Non-T1-weighted MR imaging with T2 correction and multifrequency modeling helps accurately estimate hepatic proton-density FF at 3.0 T.

Magnetic resonance imaging of oscillating electrical currents

Functional MRI has become an important tool of researchers and clinicians who seek to understand patterns of neuronal activation that accompany sensory and cognitive processes. However, the interpretation of fMRI images rests on assumptions about the relationship between neuronal firing and hemodynamic response that are not firmly grounded in rigorous theory or experimental evidence. Further, the blood-oxygen-level-dependent effect, which correlates an MRI observable to neuronal firing, evolves over a period that is 2 orders of magnitude longer than the underlying processes that are thought to cause it. Here, we instead demonstrate experiments to directly image oscillating currents by MRI. The approach rests on a resonant interaction between an applied rf field and an oscillating magnetic field in the sample and, as such, permits quantitative, frequency-selective measurements of current density without spatial or temporal cancellation. We apply this method in a current loop phantom, mapping its magnetic field and achieving a detection sensitivity near the threshold required for the detection of neuronal currents. Because the contrast mechanism is under spectroscopic control, we are able to demonstrate how ramped and phase-modulated spin-lock radiation can enhance the sensitivity and robustness of the experiment. We further demonstrate the combination of these methods with remote detection, a technique in which the encoding and detection of an MRI experiment are separated by sample flow or translation. We illustrate that remotely detected MRI permits the measurement of currents in small volumes of flowing water with high sensitivity and spatial resolution.

Spectral modulation detection training in older adults with hearing loss.

Individuals with hearing loss are poorer than normal‐hearing listeners at detecting patterns of peaks and valleys of sound level spread across audio frequency (spectral modulation detection)—an important skill for speech and music perception. In this preliminary report we examined whether listeners with hearing loss could improve on spectral modulation detection with practice. We trained older adults with sensorineural hearing loss (n=7) ∼1 hr/day for 7 days to distinguish a 400–3200 Hz noiseband with a flat‐spectrum from one with a 2 cyc/oct sinusoidal spectral modulation. Modulation depth was varied adaptively to determine the detection threshold. Their mean thresholds improved significantly from 18.9 to 12.8 dB. These listeners also improved at both a lower and a higher untrained spectral modulation frequency (1 and 4 cyc/oct), but showed no change on a measure of frequency selectivity. Interestingly, a separate group of younger normal‐hearing adults who received the same training (n=7) did not improve on the trained (6.9 to 6.6 dB) or untrained conditions. Normal‐hearing listeners had lower pre‐training thresholds than individuals with hearing loss, and across all listeners the magnitude of individual improvement was correlated to pre‐training threshold (r=0.92). Listener age and/or hearing loss could have contributed to these across‐population differences.

Optimal Settings for Frequency-Selective Measurements Used for the Exposure Assessment Around UMTS Base Stations

To estimate the exposure around a base station, the frequency-selective electromagnetic field measurement with a spectrum analyzer and antenna is the most appropriate method. In this paper, a theoretical model for the wideband code division multiaccess signal, which is measured by a spectrum analyzer, is extended to the measurement of the signal used in the universal mobile telecommunications system (UMTS), where the transmitted signal is subject to power control. The developed model is successfully validated by measurements. It is shown that the presence of power control has important implications on the achievable accuracy of the measurements. Based on the developed model, the optimal settings of the spectrum analyzer are proposed for the exposure assessment around UMTS base stations.

Exposure of the general public due to wireless LAN applications in public places

The typical exposure caused by wireless LAN applications in public areas has been investigated in a variety of scenarios. Small-sized (internet café) and large-scale (airport) indoor scenarios as well as outdoor scenarios in the environment of access points (AP) supplying for residential areas and public places were considered. The exposure assessment was carried out by numerical GTD/UTD computations based on optical wave propagation, as well as by verifying frequency selective measurements in the considered scenarios under real life conditions. In the small-sized indoor scenario the maximum temporal peak values of power density, spatially averaged over body dimensions, were found to be lower than 20 mW/m(2), corresponding to 0.2% of the reference level according to the European Council Recommendation 1999/519/EC. Local peak values of power density might be 1-2 orders of magnitude higher, spatial and time-averaged values for usual data traffic conditions might be 2-3 orders of magnitude lower, depending on the actual data traffic. In the considered outdoor scenarios, exposure was several orders of magnitude lower than in indoor scenarios due to the usually larger distances to the AP antennas.

Quantum Lithography with Classical Light

We show how to achieve subwavelength diffraction and imaging with classical light, previously thought to require quantum fields. By correlating wave vector and frequency in a narrow band, multiphoton detection process that uses Doppleron-type resonances, we show how to achieve arbitrary focal and image plane patterning with classical laser light at submultiples of the Rayleigh limit, with high efficiency, visibility, and spatial coherence. A frequency-selective measurement process thus allows one to simulate, semiclassically, the path-number correlations that distinguish a quantum entangled field.

Theoretical Derivation of the Stochastic Behavior of a WCDMA Signal Measured With a Spectrum Analyzer

Frequency-selective measurements with a spectrum analyzer are the most obvious means to accurately measure the power of a communication signal. In this paper, models for the spectrum analyzer and for the wideband code division multiaccess (WCDMA) signal are described. Based on these models, the analytic expressions for the probability density function (PDF) of the displayed signal have been derived for the different detection modes [sample, root mean square (rms) and positive-peak detection] of the spectrum analyzer. Based on these theoretical considerations, the dependence of the mean and standard deviation of the measured signal on the observation time of the detector has been examined, which showed a good agreement with the simulated results.

Frequency-selective Power Transducers: Hexagonal Ferrite Resonator-semiconductor Element

The transducers studied herein allow for frequency-selective measurement of mm-wave power parameters. Frequency selectivity is assured by a monocrystalline hexagonal ferrite resonator (HFR). The HFR is in direct contact with a semiconductor element (SE)—an unpackaged Hall-element, or a chip transistor (or diode). Power absorbed by the HFR at the ferromagnetic resonance converts to heat, and the heat flux penetrates through the current-carrying SE. A number of thermo/electro/magnetic phenomena accompany the Hall-effect in a semiconductor and cause a voltage in addition to the Hall-effect voltage. The conversion coefficient of a transducer is analyzed using the power balance equation. Some experimental results using the designed power transducers in the 8-mm waveband are presented.