Widex (Denmark)

Virtual reality-based cognitive remediation therapy (VR-CRT) offers an ecologically valid approach to enhance real-world cognitive functioning in mood disorders (MD) or schizophrenia spectrum disorders (SSD). This study investigated baseline cognitive, clinical, and neural predictors of VR-CRT response in MD and SSD. Sixty-two MD and SSD participants were randomized to receive four-week VR-CRT or control with assessments at baseline, treatment completion (week 5), and follow-up (week 17). Univariate general linear models examined predictors of VR-CRT improvement on daily-life cognitive skills, assessed using the Cognition Assessment in Virtual Reality (CAVIR). Predictors included age, diagnosis, baseline cognition, IQ-cognition discrepancy, dorsal prefrontal cortex (dPFC) activation during a working memory task, functional connectivity within the dorsal attention (DAN) and salience (SAL) networks, subjective cognition, and technological acceptance. Higher IQ-cognition discrepancy at baseline (i.e., better cognitive performance than expected from premorbid IQ) predicted greater treatment efficacy at treatment completion (β=0.17, p=0.045) and follow-up (β=0.21, p=0.008), while baseline cognition was not associated with treatment response (ps≥0.15). Higher baseline dPFC activity predicted more improvements at both times (β=2.27 p=0.03; β=1.82; p=0.048, respectively). Higher DAN-SAL connectivity predicted improvements at treatment completion (β=2.81 p=0.047), but not at follow-up (p=0.38). Age, sex, diagnosis, subjective cognition, and technological acceptance were not associated with cognitive change. Better cognitive performance than expected based on IQ, possibly reflecting higher cognitive fitness, and greater task-related engagement of dPFC may enhance VR-CRT responsiveness. This profile may indicate greater readiness for change and propensity to translate cognitive strategies into daily life.

It has been suggested that hearing-impaired listeners with a good working memory (WM) should be fitted with a compression system using short time constants (i.e., fast-acting compression [FAC]), whereas those with a poorer WM should be fitted with a longer time constant (i.e., slow-acting compression [SAC]). However, commercial hearing aids (HAs) seldom use a fixed speed of compression. The performance of a variable speed compression (VSC) system relative to a fixed speed compressor (FAC and SAC) on measures of speech intelligibility, recall, and subjective report of listening effort and tolerable time was evaluated. The potential interaction with the listeners' WM capacity (WMC) was also examined. A double-blinded, repeated measures design. Seventeen HA wearers (16 with greater than one year HA experience) with a bilaterally symmetrical, mild to moderately severe sensorineural hearing loss participated in the study. Participants wore the study HAs at three compression speeds (FAC, SAC, and VSC). Each listener was evaluated on the Office of Research in Clinical Amplification-nonsense syllable test (NST) at 50 dB SPL (signal-to-noise ratio [SNR] = +15 dB), 65 dB SPL (SNR = +5 dB), 80 dB SPL (SNR = 0 dB), and a split (80 dB SPL-50 dB SPL) condition. Listeners were also evaluated on a Repeat Recall Test (RRT), where they had to repeat six short sentences (both high- and low-context sentences) after each was presented. Listeners recalled target words in all six sentences after they were presented. They also rated their listening effort and the amount of time they would tolerate listening under the specific condition. RRT sentences were presented at 75 dB SPL in quiet, as well as SNR = 0, 5, 10, and 15 dB. A Reading Span Test (RST) was also administered to assess listeners' WMC. Analysis of variance using RST scores as a covariate was used to examine differences in listener performance among compressor speeds. Listener performance on the NST was similar among all three compression speeds at 50, 65, and 80 dB SPL. Performance with FAC was significantly better than SAC for the split condition; however, performance did not differ between FAC and VSC or between SAC and VSC. Performance on the NST was not affected by listeners' RST scores. On the RRT, there was no effect of compressor speed on measures of repeat, recall, listening effort, and tolerable time. However, VSC resulted in significantly lower (better) speech reception threshold at the 85% correct recognition criterion (SRT85) than FAC and SAC. Listener RST scores significantly affected recall performance on the RRT but did not affect SRT85, repeat, listening effort, or tolerable time. These results suggest that the VSC, FAC, and SAC yield similar performance in most but not all test conditions. FAC outperforms SAC, where the stimulus levels change abruptly (i.e., split condition). The VSC yields a lower SRT85 than a fixed compression speed at a moderately high level with a favorable SNR. There is no interaction between compression speed and the participants' WMC.

The analysis of conversational signal-to-noise ratios (SNRs) measured in real-world scenarios can provide vital insight into people's communicative strategies and difficulties and guide development of hearing devices. However, measuring SNRs accurately and realistically is challenging in typical recording conditions, where only a mixture of sound sources is captured. This study introduces a novel method for realistic in situ SNR estimation, where the speech signal of a person in natural conversation is captured by a cheek-mounted microphone, adjusted for free-field conditions, and convolved with a measured impulse response to estimate the clean speech component at the receiver. A microphone near the receiver computes the noise-only component by applying a voice activity detector. Obtained SNR values are analyzed using in situ recordings of a real-world workspace meeting. It is shown that the temporal resolution is increased, and fluctuations in the speech level are more accurately tracked compared to a typical spectral-subtraction-derived method. The application of the proposed SNR estimation method may be valuable for compensation procedures in hearing instruments that take conversational dynamics into account.

The purpose was to investigate the effects of hearing-loss and fast-acting compression on speech intelligibility and two measures of temporal modulation sensitivity. Twelve adults with normal hearing (NH) and 16 adults with mild to moderately severe sensorineural hearing loss were tested. Amplitude modulation detection and modulation-depth discrimination (MDD) thresholds with sinusoidal carriers of 1 or 5 kHz and modulators in the range from 8 to 256 Hz were used as measures of temporal modulation sensitivity. Speech intelligibility was assessed by obtaining speech reception thresholds in stationary and fluctuating background noise. All thresholds were obtained with and without compression (using a fixed compression ratio of 2:1). For modulation detection, the thresholds were similar or lower for the group with hearing loss than for the group with NH. In contrast, the MDD thresholds were higher for the group with hearing loss than for the group with NH. Fast-acting compression increased the modulation detection thresholds, while no effect of compression on the MDD thresholds was observed. The speech reception thresholds obtained in stationary noise were slightly increased in the compression condition relative to the linear processing condition, whereas no difference in the speech reception thresholds obtained in fluctuating noise was observed. For the group with NH, individual differences in the MDD thresholds could account for 72% of the variability in the speech reception thresholds obtained in stationary noise, whereas the correlation was insignificant for the hearing-loss group. Fast-acting compression can restore modulation detection thresholds for listeners with hearing loss to the values observed for listeners with NH. Despite this normalization of the modulation detection thresholds, compression does not seem to provide a benefit for speech intelligibility. Furthermore, fast-acting compression may not be able to restore MDD thresholds to the values observed for listeners with NH, suggesting that the two measures of amplitude modulation sensitivity represent different aspects of temporal processing. For listeners with NH, the ability to discriminate modulation depth was highly correlated with speech intelligibility in stationary noise.

In this paper, a delayless speech enhancement scheme with zero phase distortion is proposed. It is based on a cascade of adaptive filters that predicts periodic components with a significant auto-correlation for lags larger than a value D. The adaptive filter is positioned at the output of a speech enhancement algorithm, to adjust the phase of the periodic components to the noisy signal, and to remove stochastic signal components with a significant auto-correlation only for lags smaller than D. The stochastic components are enhanced in a separate channel and mixed back together with the periodic components to give an output with no delay or phase distortion compared to the input signal. Such a scheme is useful for low-delay processing where the phase of the signal must be preserved, for instance as a front-end for spatial filtering or when the output is mixed with another source, such as the direct transmitted sound through the vent in an open hearing aid fitting.

A method for brain monitoring based on measuring the electroencephalogram (EEG) from electrodes placed in-the-ear (ear-EEG) was recently proposed. The objective of this study is to further characterize the ear-EEG and perform a rigorous comparison against conventional on-scalp EEG. This is achieved for both auditory and visual evoked responses, over steady-state and transient paradigms, and across a population of subjects. The respective steady-state responses are evaluated in terms of signal-to-noise ratio and statistical significance, while the qualitative analysis of the transient responses is performed by considering grand averaged event-related potential (ERP) waveforms. The outcomes of this study demonstrate conclusively that the ear-EEG signals, in terms of the signal-to-noise ratio, are on par with conventional EEG recorded from electrodes placed over the temporal region.

An increasing number of hearing aid types include one or more features which are intentionally non-linear. In such devices measurement of frequency response and distortion using sweep tone measurements are typically of little relevance. Five different non-linear hearing aid types were used to evaluate three different broad-band measuring methods. The results revealed that these methods were meaningful in estimating average frequency response obtained with a specific input signal, but none of the three methods used in the study was able to evaluate separately the effects of the most important signal modifications: memoryless non-linearity like peak clipping, time-varying gain from AGC and additive internal noise.