Neurodynamic evaluation of hearing aid features using EEG correlates of listening effort

In this study, we propose a novel estimate of listening effort using electroencephalographic data. This method is a translation of our past findings, gained from the evoked electroencephalographic activity, to the oscillatory EEG activity. To test this technique, electroencephalographic data from experienced hearing aid users with moderate hearing loss were recorded, wearing hearing aids. The investigated hearing aid settings were: a directional microphone combined with a noise reduction algorithm in a medium and a strong setting, the noise reduction setting turned off, and a setting using omnidirectional microphones without any noise reduction. The results suggest that the electroencephalographic estimate of listening effort seems to be a useful tool to map the exerted effort of the participants. In addition, the results indicate that a directional processing mode can reduce the listening effort in multitalker listening situations

Vestigial auriculomotor activity indicates the direction of auditory attention in humans

Unlike dogs and cats, people do not point their ears as they focus attention on novel, salient, or task-relevant stimuli. Our species may nevertheless have retained a vestigial pinna-orienting system that has persisted as a 'neural fossil’ within in the brain for about 25 million years. Consistent with this hypothesis, we demonstrate that the direction of auditory attention is reflected in sustained electrical activity of muscles within the vestigial auriculomotor system. Surface electromyograms (EMGs) were taken from muscles that either move the pinna or alter its shape. To assess reflexive, stimulus-driven attention we presented novel sounds from speakers at four different lateral locations while the participants silently read a boring text in front of them. To test voluntary, goal-directed attention we instructed participants to listen to a short story coming from one of these speakers, while ignoring a competing story from the corresponding speaker on the opposite side. In both experiments, EMG recordings showed larger activity at the ear on the side of the attended stimulus, but with slightly different patterns. Upward movement (perking) differed according to the lateral focus of attention only during voluntary orienting; rearward folding of the pinna’s upper-lateral edge exhibited such differences only during reflexive orienting. The existence of a pinna-orienting system in humans, one that is experimentally accessible, offers opportunities for basic as well as applied science

Comparing Three Established Methods for Tinnitus Pitch Matching With Respect to Reliability, Matching Duration, and Subjective Satisfaction

The pitch of tinnitus sound is a key characteristic that is of importance to research and sound therapies relying on exact tinnitus pitch matches. The identification of this tinnitus pitch is a challenging task as there is no objective measurement available. During the tinnitus pitch-matching procedure, the participant identifies an external sound that is most similar to the subjective perception of the tinnitus. Several methods have been developed to perform this pitch-matching procedure with tinnitus sufferers. In this study, we aimed to compare the method of adjustment, the two-alternative forced-choice (2AFC) method, and the likeness rating (LR) with respect to reliability, matching duration, and subjective satisfaction. Fifty-nine participants with chronic tinnitus were recruited and performed five consecutive runs of tinnitus matching. The participants were randomized to the three different pitch-matching methods. The intraclass correlation coefficients were .67 for method of adjustment, .63 for 2AFC, and .69 for LR, which can be interpreted as good reliability for all the three methods. However, the 2AFC method revealed significant larger within-subject variability than the other measures. Across the five runs and the three different methods, all participants learned to perform the pitch matching faster and with better self-rated accuracy. Comparing the three pitch-matching methods, LR is more time consuming and the participants were less satisfied with the 2AFC method. Overall, the three pitch-matching methods show good reliability. However, we identified differential aspects for improvement in all methods, which are discussed in this article

Combining Mobile Crowdsensing and Ecological Momentary Assessments in the Healthcare Domain

The increasing prevalence of smart mobile devices (e.g., smartphones) enables the combined use of mobile crowdsensing (MCS) and ecological momentary assessments (EMA) in the healthcare domain. By correlating qualitative longitudinal and ecologically valid EMA assessment data sets with sensor measurements in mobile apps, new valuable insights about patients (e.g., humans who suffer from chronic diseases) can be gained. However, there are numerous conceptual, architectural and technical, as well as legal challenges when implementing a respective software solution. Therefore, the work at hand (1) identifies these challenges, (2) derives respective recommendations, and (3) proposes a reference architecture for a MCS-EMA-platform addressing the defined recommendations. The required insights to propose the reference architecture were gained in several large-scale mHealth crowdsensing studies running for many years and different healthcare questions. To mention only two examples, we are running crowdsensing studies on questions for the tinnitus chronic disorder or psychological stress. We consider the proposed reference architecture and the identified challenges and recommendations as a contribution in two respects. First, they enable other researchers to align our practical studies with a baseline setting that can satisfy the variously revealed insights. Second, they are a proper basis to better compare data that was gathered using MCS and EMA. In addition, the combined use of MCS and EMA increasingly requires suitable architectures and associated digital solutions for the healthcare domain

Reparatur unzureichender Sprachsignale: Evidenz ereigniskorrelierter Hirnantworten

The comprehension of speech is an extraordinary ability of the human cognitive system. Listeners are capable of recognizing speech efficiently and rapidly under an exceedingly broad range of acoustic environmental conditions. Even if segments of the speech signal are acoustically not present or heavily distorted these disturbances may not impede the comprehension of speech.In a series of EEG experiments different repair processes in speech perception using lexical top-down information were examined. It was hypothesized that a successful recovery of deficient speech results in resonant states which are reflected in the induced gamma band activity (GBA). Instead, if the general conditions of an ambiguous speech event prevent the repair process, this failure should be reflected in an error signal, i.e. the mismatch negativity (MMN). All these processes were expected to be influenced by the overall structure of representations in the mental lexicon.The findings of the present thesis revealed a direct correlate for the facilitating influence of top-down knowledge on speech comprehension under adverse listening conditions in the induced GBA. Twice, a modulation in the 40 Hz range over left anterior temporal electrode sites was reported. Further, the present results evinced deep insights in the general conditions that allow for a repair of deficient speech. Only if the expected phonemic information matches somewhat the characteristics of the incoming stimulus a successful repair was evident. On the contrary, an explicit difference between the sensory and the expected information prevent the recovery of deficient speech and revealed a distinct MMN over frontal electrode sites. Moreover, at least for the phonemic restoration illusion, the induced GBA as well as the MMN responses corroborated the hypothesis of sparse representations in the mental lexicon (Lahiri and Reetz, 2002).Taken together, the present data show experimentally how comprehending speech and the bottom-up brain processes mediating it depend highly on memory-driven (i.e., top-down) expectancies. Finally, the present data are in line with recent models of speech perception relying on Bayesian statistics (Friston, 2005; Norris and McQueen, 2008) by demonstrating how the cognitive system adapts in an optimal way to a complex and constant changing environment

Comparing Three Established Methods for Tinnitus Pitch Matching With Respect to Reliability, Matching Duration, and Subjective Satisfaction

The pitch of tinnitus sound is a key characteristic that is of importance to research and sound therapies relying on exacttinnitus pitch matches. The identification of this tinnitus pitch is a challenging task as there is no objective measurementavailable. During the tinnitus pitch-matching procedure, the participant identifies an external sound that is most similar tothe subjective perception of the tinnitus. Several methods have been developed to perform this pitch-matching procedurewith tinnitus sufferers. In this study, we aimed to compare the method of adjustment, the two-alternative forced-choice(2AFC) method, and the likeness rating (LR) with respect to reliability, matching duration, and subjective satisfaction. Fifty-nine participants with chronic tinnitus were recruited and performed five consecutive runs of tinnitus matching. Theparticipants were randomized to the three different pitch-matching methods. The intraclass correlation coefficients were.67 for method of adjustment, .63 for 2AFC, and .69 for LR, which can be interpreted as good reliability for all the threemethods. However, the 2AFC method revealed significant larger within-subject variability than the other measures. Acrossthe five runs and the three different methods, all participants learned to perform the pitch matching faster and with betterself-rated accuracy. Comparing the three pitch-matching methods, LR is more time consuming and the participants were lesssatisfied with the 2AFC method. Overall, the three pitch-matching methods show good reliability. However, we identifieddifferential aspects for improvement in all methods, which are discussed in this article

Opaque for the reader but transparent for the brain: Neural signatures of morphological complexity

Within linguistics. words with a complex internal structure are commonly assumed to be decomposed into their constituent morphemes (e.g., un-help-ful). Nevertheless, an ongoing debate concerns the brain structures that subserve this process. Using functional magnetic resonance imaging, the present study varied the internal complexity of derived words while keeping the external surface structure constant as well as controlling relevant parameters that could affect word recognition. This allowed us to tease apart brain activations specifically related to morphological processing from those related to possible confounds of perceptual cues like word length or affix type. Increased task-related activity in left inferior frontal, bilateral temporo-occipital and right parietal areas was specifically related to the processing of derivations with high complex internal structure relative to those with low complex internal structure. Our results show, that morphologically complex words are decomposed and that the brain processes the degree of internal complexity of word derivations

Testing the Limits of the Stimulus Reconstruction Approach: Auditory Attention Decoding in a Four-Speaker Free Field Environment

Auditory attention can be defined as the cognitive process that enables us to selectively focus on relevant aspects of the acoustic environment while other aspects are ignored. The remarkable ability of the auditory system to focus on one out of several speakers in a multispeaker environment has become known as the cocktail party effect . Although the neural processes underlying selective auditory attention (SAA) are not well understood, it has recently been shown that the cortical representation of a listener’s attended sound stream can be recorded noninvasively from the scalp and that stimulus reconstruction from single trial electroencephalographic (EEG) data enables the decoding of the orientation of auditory attention. The present study extends this approach by evaluating its efficacy in a naturalistic and challenging four-speaker acoustic free field environment, in which the four speakers were spatially separated and presented different but equally salient spoken messages to the listeners. Ten participants were instructed to focus SAA on a spoken prose message in one of the four loudspeakers while ignoring the remaining three streams of prose. Concurrent EEG activity recorded via 128 scalp channels was used for a stimulus reconstruction analysis. The results showed that this approach can be used to decode the orientation of SAA even in a complex and realistic acoustic setting. To confirm that the successful decoding was driven by correspondences between the recorded EEG activity and the attended speech envelopes, the analysis method was validated against randomly constructed sets of surrogate data and by correlations with behavioral data