The development of a modified spectral ripple test.
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ABSTRACT:
SUBMITTER: Aronoff JM
PROVIDER: S-EPMC3732300 | biostudies-other | 2013 Aug
REPOSITORIES: biostudies-other
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Project description:OBJECTIVES:Although speech perception is the gold standard for measuring cochlear implant (CI) users' performance, speech perception tests often require extensive adaptation to obtain accurate results, particularly after large changes in maps. Spectral ripple tests, which measure spectral resolution, are an alternate measure that has been shown to correlate with speech perception. A modified spectral ripple test, the spectral-temporally modulated ripple test (SMRT) has recently been developed, and the objective of this study was to compare speech perception and performance on the SMRT for a heterogeneous population of unilateral CI users, bilateral CI users, and bimodal users. DESIGN:Twenty-five CI users (eight using unilateral CIs, nine using bilateral CIs, and eight using a CI and a hearing aid) were tested on the Arizona Biomedical Institute Sentence Test (AzBio) with a +8 dB signal to noise ratio, and on the SMRT. All participants were tested with their clinical programs. RESULTS:There was a significant correlation between SMRT and AzBio performance. After a practice block, an improvement of one ripple per octave for SMRT corresponded to an improvement of 12.1% for AzBio. Additionally, there was no significant difference in slope or intercept between any of the CI populations. CONCLUSION:The results indicate that performance on the SMRT correlates with speech recognition in noise when measured across unilateral, bilateral, and bimodal CI populations. These results suggest that SMRT scores are strongly associated with speech recognition in noise ability in experienced CI users. Further studies should focus on increasing both the size and diversity of the tested participants, and on determining whether the SMRT technique can be used for early predictions of long-term speech scores, or for evaluating differences among different stimulation strategies or parameter settings.
| S-EPMC5741801 | biostudies-literature
Project description:Cochlear implant (CI) users can achieve remarkable speech understanding, but there is great variability in outcomes that is only partially accounted for by age, residual hearing, and duration of deafness. Results might be improved with the use of psychophysical tests to predict which sound processing strategies offer the best potential outcomes. In particular, the spectral-ripple discrimination test offers a time-efficient, nonlinguistic measure that is correlated with perception of both speech and music by CI users. Features that make this "one-point" test time-efficient, and thus potentially clinically useful, are also connected to controversy within the CI field about what the test measures. The current work examined the relationship between thresholds in the one-point spectral-ripple test, in which stimuli are presented acoustically, and interaction indices measured under the controlled conditions afforded by direct stimulation with a research processor. Results of these studies include the following: (1) within individual subjects there were large variations in the interaction index along the electrode array, (2) interaction indices generally decreased with increasing electrode separation, and (3) spectral-ripple discrimination improved with decreasing mean interaction index at electrode separations of one, three, and five electrodes. These results indicate that spectral-ripple discrimination thresholds can provide a useful metric of the spectral resolution of CI users.
| S-EPMC3548834 | biostudies-other
Project description:Measures of spectral ripple resolution have become widely used psychophysical tools for assessing spectral resolution in cochlear-implant (CI) listeners. The objective of this study was to compare spectral ripple discrimination and detection in the same group of CI listeners. Ripple detection thresholds were measured over a range of ripple frequencies and were compared to spectral ripple discrimination thresholds previously obtained from the same CI listeners. The data showed that performance on the two measures was correlated, but that individual subjects' thresholds (at a constant spectral modulation depth) for the two tasks were not equivalent. In addition, spectral ripple detection was often found to be possible at higher rates than expected based on the available spectral cues, making it likely that temporal-envelope cues played a role at higher ripple rates. Finally, spectral ripple detection thresholds were compared to previously obtained speech-perception measures. Results confirmed earlier reports of a robust relationship between detection of widely spaced ripples and measures of speech recognition. In contrast, intensity difference limens for broadband noise did not correlate with spectral ripple detection measures, suggesting a dissociation between the ability to detect small changes in intensity across frequency and across time.
| S-EPMC3529540 | biostudies-other
Project description:Spectral-ripple discrimination has been used widely for psychoacoustical studies in normal-hearing, hearing-impaired, and cochlear implant listeners. The present study investigated the perceptual mechanism for spectral-ripple discrimination in cochlear implant listeners. The main goal of this study was to determine whether cochlear implant listeners use a local intensity cue or global spectral shape for spectral-ripple discrimination. The effect of electrode separation on spectral-ripple discrimination was also evaluated. Results showed that it is highly unlikely that cochlear implant listeners depend on a local intensity cue for spectral-ripple discrimination. A phenomenological model of spectral-ripple discrimination, as an "ideal observer," showed that a perceptual mechanism based on discrimination of a single intensity difference cannot account for performance of cochlear implant listeners. Spectral modulation depth and electrode separation were found to significantly affect spectral-ripple discrimination. The evidence supports the hypothesis that spectral-ripple discrimination involves integrating information from multiple channels.
| S-EPMC3206911 | biostudies-other
Project description:Speech perception ability in noise is one of the most practical measures of success with a cochlear implant; however, with experience, this ability can change dramatically over time, making it a less than ideal tool for comparing performance among different processing strategies. This study examined performance on a spectral discrimination task and compared it to speech perception in noise. An adaptive procedure was used to determine the spectral-ripple density that subjects could discriminate. A closed-set, forced-choice adaptive procedure was used to determine speech reception thresholds for words in two-talker babble and in speech-shaped, steady-state noise. Spectral-ripple thresholds (ripples/octave) were significantly correlated with speech reception thresholds (dB SNR) in noise for 29 cochlear implant users (r = -0.55, p = 0.002 in two-talker babble; r = -0.62, p = 0.0004 in steady-state noise), demonstrating that better spectral resolution was associated with better speech perception in noise. A significant correlation was also found between the spectral-ripple discrimination ability and word recognition in quiet (r = 0.50, p = 0.009). In addition, test-retest reliability for spectral-ripple discrimination was good, and no learning was observed. The present study demonstrates that the spectral-ripple discrimination test, which is time efficient and nonlinguistic, would be a useful tool to evaluate cochlear implant performance with different signal processing strategies.
| S-EPMC2538435 | biostudies-other
Project description:Spectral ripple discrimination thresholds were measured in 15 cochlear-implant users with broadband (350-5600 Hz) and octave-band noise stimuli. The results were compared with spatial tuning curve (STC) bandwidths previously obtained from the same subjects. Spatial tuning curve bandwidths did not correlate significantly with broadband spectral ripple discrimination thresholds but did correlate significantly with ripple discrimination thresholds when the rippled noise was confined to an octave-wide passband, centered on the STC's probe electrode frequency allocation. Ripple discrimination thresholds were also measured for octave-band stimuli in four contiguous octaves, with center frequencies from 500 Hz to 4000 Hz. Substantial variations in thresholds with center frequency were found in individuals, but no general trends of increasing or decreasing resolution from apex to base were observed in the pooled data. Neither ripple nor STC measures correlated consistently with speech measures in noise and quiet in the sample of subjects in this study. Overall, the results suggest that spectral ripple discrimination measures provide a reasonable measure of spectral resolution that correlates well with more direct, but more time-consuming, measures of spectral resolution, but that such measures do not always provide a clear and robust predictor of performance in speech perception tasks.
| S-EPMC3155592 | biostudies-other
Project description:This study sought to demonstrate and evaluate a novel spectral fitting method to improve quantification accuracy in the presence of large magnetic field distortion, especially with high fields. MRS experiments were performed using a point-resolved spectroscopy (PRESS)-type sequence at 7?T. A double-echo gradient echo (GRE) sequence was used to acquire B0 maps following MRS experiments. The basis set was modified based on the measured B0 distribution within the MRS voxel. Quantification results were obtained after fitting the measured MRS data using the modified basis set. The proposed method was validated using numerical Monte Carlo simulations, phantom measurements, and comparison of occipital lobe MRS measurements under homogeneous and inhomogeneous magnetic field conditions. In vivo results acquired from voxels placed in thalamus and prefrontal cortex regions close to the frontal sinus agreed well with published values. Instead of noise-amplifying complex division, the proposed method treats field variations as part of the signal model, thereby avoiding inherent statistical bias associated with regularization. Simulations and experiments showed that the proposed approach reliably quantified results in the presence of relatively large magnetic field distortion. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
| S-EPMC4715526 | biostudies-literature
Project description:Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii?<?30??m) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50?km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10??m) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200?m, a width of ~2?km and length of between 2 and 12?km. Concentrations of ~200??g?m(-3) were identified by AVOID at distances from ~20?km to ~70?km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft.
| S-EPMC4860601 | biostudies-literature
Project description:ObjectiveThe 10 m modified shuttle walking test (MSWT) is recommended to determine the functional capacity in older individuals and for patients entering cardiac rehabilitation. Participants are required to negotiate around cones set 1 m from the end markers. However, consistent comments indicate that for some individuals manoeuvring around the cones can be quite difficult. Therefore, the objective of this study was to explore differences within and between non-cardiac and postmyocardial infarction (MI) males during MSWT with and without the cones.DesignComparative study.Participants20 post-MI (64.8±6.6, range 51-74 years) and 20 non-cardiac male controls (64.1±5.7, range 52-74 years) participated.MethodsParticipants performed MSWT with and without cones. Throughout, the participants expired air, and the heart rate (bpm) (HR) and ratings of perceived exertion (RPE) were measured. Participant protocol preference was recorded verbatim.ResultsOne-way analysis of variance found no significant difference in VO2 peak (cones 20.4±5.1 vs no-cones 21.9±4.8 ml/kg/min, p=0.197) or distance ambulated (cones 631.8±132.9 m vs no-cones 662.4±164.1 m, p=0.371) between protocols or groups. Analysis comparing lines of regression showed a significant trajectory difference in VO2 (ml/kg/min) (p<0.01) between protocols with higher HR (p<0.01) and respiratory exchange ratio (RER, p<0.001) values during cones. RPEs were higher for post-MIs versus controls during both protocols (p<0.05). Post-MIs taking ?-blockers produce significantly lower HR values. The ?(2) analysis found no significant difference in protocol preference (no-cones: all n=25, 63%; post-MIs n=13, 65%; and controls n=12, 60%).ConclusionsPost-MIs found both protocols subjectively harder than controls with no significant difference in the VO2 peak. However, both groups worked at a lesser percentage of their anaerobic threshold during no-cones protocol as indicated by lower RER values. Importantly, for the post-MIs, this would reduce their risk of functional impairment. Therefore, though more research is required, indicators at present are more favourable for the use of the no-cones with post-MIs.
| S-EPMC3664357 | biostudies-literature
Project description:Pyroelectricity originates from spontaneous polarization variation, promising in omnipresent non-static thermodynamic energy harvesting. Particularly, changing spontaneous polarization via out-of-plane uniform heat perturbations has been shown in solar pyroelectrics. However, these approaches present unequivocal inefficiency due to spatially coupled low temperature change and duration along the longitudinal direction. Here we demonstrate unconventional giant polarization ripples in transverse pyroelectrics, without increasing the total energy input, into electricity with an efficiency of 5-fold of conventional longitudinal counterparts. The non-uniform graded temperature variation arises from decoupled heat localization and propagation, leading to anomalous in-plane heat perturbation (29-fold) and enhanced thermal disequilibrium effects. This in turn triggers an augmented polarization ripple, fundamentally enabling unprecedented electricity generation performance. Notably, the device generates a power density of 38 mW m-2 at 1 sun illumination, which is competitive with solar thermoelectrics and ferrophotovoltaics. Our findings provide a viable paradigm, not only for universal practical pyroelectric heat harvesting but for flexible manipulation of transverse heat transfer towards sustainable energy harvesting and management.
| S-EPMC9879950 | biostudies-literature