EAS-Combined electric and acoustic stimulation.

Electric-acoustic stimulation (EAS) is a special treatment modality for those patients who are profoundly deaf in the high-frequency (HF) region and retain usable hearing in the low-frequency (LF) region. Combining the electric stimulation with cochlear implant (CI) in the HF and acoustic amplification of residual hearing using a conventional hearing aid (HA) in the LF region defines EAS. The EAS concept was first proposed by C. von Ilberg from Frankfurt, Germany in the year 1997. In association with MED-EL, all the necessary safety studies were performed in non-human subjects before the first patient received it in 1997. In association with MED-EL, all the necessary safety studies were performed in non-human subjects before the first patient received it in 1999. For the patient to successfully use the EAS concept, the residual hearing needs to be preserved to a high extent and for several years. This requires a highly flexible electrode array in safeguarding the intra-cochlear structures during and after the CI electrode array insertion. Combining the HA unit with the audio processor unit of the CI was necessary for the convenient wearing of the unified audio processor. Fitting of the unified audio processor is another important factor that contributes to the overall success of the EAS treatment. The key translational research efforts at MED-EL were on the development of flexible electrodes, a unified audio processor, innovations in the fitting process, intra-operative monitoring of cochlear health during electrode insertion, pre-operative soft-ware tool to evaluate the cochlear size and electrode selection and some new innovations tried within EAS topic. This article covers the milestones of translational research from the first concept to the widespread clinical use of EAS.

Feasibility of a rhythmic auditory stimulation gait training program in community-dwelling adults after TBI: A case report.

BACKGROUND: Traumatic brain injury has multiple impacts on gait including decreased speed and increased gait variability. Rhythmic auditory stimulation (RAS) gait training uses the rhythm and timing structure of music to train and ultimately improve slow and variable walking patterns. OBJECTIVE: To describe the feasibility of RAS gait training in community-dwelling adults with traumatic brain injury (TBI). A secondary objective is to report changes in spatiotemporal gait parameters and clinical measures of balance and walking endurance. METHODS: Two individuals with a TBI participated in nine sessions of gait training with RAS over a 3-week period. At baseline, post-training and 3-week follow-up, spatiotemporal parameters of walking were analyzed at preferred pace, maximum pace and dual-task walking conditions. Secondary outcomes included the Community Balance and Mobility Scale and the 6-Minute Walk Test. Feasibility was assessed using reports of physical fatigue, adverse event reporting, and perceived satisfaction. RESULTS: Both participants completed all 9 planned intervention sessions. The sessions were well tolerated with no adverse events. Participant 1 and 2 exhibited different responses to the intervention in line with the therapeutic goals set with the therapist. Participant 1 exhibited improved speed and decreased gait variability. Participant 2 exhibited reduced gait speed but less fatigue during the 6MWT. CONCLUSIONS: RAS was found to be a safe and feasible gait intervention with the potential to improve some aspects of gait impairments related to gait speed, gait variability, dynamic balance and walking endurance. Further investigation including a pilot randomized controlled trial is warranted.

Neural tracking of the speech envelope in cochlear implant users.

OBJECTIVE: When listening to speech, the brain tracks the speech envelope. It is possible to reconstruct this envelope from EEG recordings. However, in people who hear using a cochlear implant (CI), the artifacts caused by electrical stimulation of the auditory nerve contaminate the EEG. The objective of this study is to develop and validate a method for assessing the neural tracking of speech envelope in CI users. APPROACH: To obtain EEG recordings free of stimulus artifacts, the electrical stimulation is periodically interrupted. During these stimulation gaps, artifact-free EEG can be sampled and used to train a linear envelope decoder. EEG recordings obtained during audible and inaudible (i.e. sub-threshold) stimulation were used to characterize the artifacts and their influence on the envelope reconstruction. MAIN RESULTS: The present study demonstrates for the first time that neural tracking of the speech envelope can be measured in response to ongoing electrical stimulation. The responses were validated to be truly neural and not affected by stimulus artifact. SIGNIFICANCE: Besides applications in audiology and neuroscience, the characterization and elimination of stimulus artifacts will enable future EEG studies involving continuous speech in CI users. Measures of neural tracking of the speech envelope reflect interesting properties of the listener's perception of speech, such as speech intelligibility or attentional state. Successful decoding of neural envelope tracking will open new possibilities to investigate the neural mechanisms of speech perception with a CI.

Future perspectives on neural mechanisms underlying rhythm and music based neurorehabilitation in Parkinson's disease.

Parkinson's disease (PD) is characterized primarily by a dysfunctional basal ganglia (BG) system, producing motor and non-motor symptoms. A significant number of studies have demonstrated that rhythmic auditory stimulation can improve gait and other motor behaviors in PD that are not well managed by the conventional therapy. As music, being highly complex stimulus, can modulate brain activity/function in distributed areas of brain, the therapeutic properties of music potentially extend to alleviate non-motor symptoms of PD. Despite the clinical, behavioral evidence and promises of rhythm and music based interventions, the neural substrates underlying the effectiveness are poorly understood. The goal of this review is to appraise the current state of knowledge in order to direct further neuroimaging studies that help to determine the therapeutic effects of rhythm and music based interventions for motor and non-motor symptoms of PD.

The impact of sound exposure on heart rate variability in adolescent students.

Previous studies of physiological responses to music and noise showed the effect on the autonomic nervous system. The heart rate variability (HRV) has been used to assess the activation of the sympathetic and the parasympathetic nervous systems. The present study was aimed to examine HRV with exposure to four sine-wave pure tones (20 Hz, 50 Hz, 2 kHz and 15 kHz) in an environment where the sound intensity exceeded level 65 dB (A-weighted). The participants (20 adolescent girls) were lying in supine position during exposure protocol divided into 6 periods, the first time with generated sounds and the second time without sounds. In the protocol without sound exposure, the low frequency band of the HRV spectrum was increased compared to the basal state before examination (period_1: 6.05+/-0.29 ms(2) compared to period_5: 6.56+/-0.20 ms(2), p<0.05). The significant increase of root Mean Square of the Successive Differences (rMSSD, period_1: 4.09+/-0.16 s compared to period_6: 4.33+/-0.12 s, p<0.05) and prolongation of R to R peak (RR) interval (period_1: 889+/-30 ms compared to period_5: 973+/-30 ms, p<0.001) were observed in the protocol without sound exposure comparing to the protocol with sound exposure where only bradycardia was observed. Contrary to rather polemical data in literature our pilot study suggests that sounds (under given frequencies) have no impact on the heart rate variability and cardiac autonomic regulation.

[Technical advancements in cochlear implants : State of the art]. / Technische Entwicklungen bei Cochleaimplantaten : Stand der Technik.

Twenty years ago, cochlear implants (CI) were indicated only in cases of profound hearing loss or complete deafness. While from today's perspective the technology was clumsy and provided patients with only limited speech comprehension in quiet scenarios, successive advances in CI technology and the consequent substantial hearing improvements over time have since then resulted in continuous relaxation of indication criteria toward residual hearing. While achievements in implant and processor electronics have been one key factor for the ever-improving hearing performance, development of electro-acoustic CI systems-together with atraumatic implantation concepts-has led to enormous improvements in patients with low-frequency residual hearing. Manufactures have designed special processors with integrated hearing aid components for this patient group, which are capable of conveying acoustic and electric stimulation. A further milestone in improvement of hearing in challenging listening environments was the adoption of signal enhancement algorithms and assistive listening devices from the hearing aid industry. This article gives an overview of the current state of the art in the abovementioned areas of CI technology.

The future of psychiatry: brain devices.

Recent advances in deep brain stimulators and brain-machine interfaces have greatly expanded the possibilities of neuroprosthetics and neuromodulation. Together with advances in neuroengineering, nanotechnology, molecular biology and material sciences, it is now possible to address fundamental questions in neuroscience in new, more powerful ways. It is now possible to apply these new technologies in ways that range from augmenting and restoring function to neuromodulation modalities that treat neuropsychiatric disorders. Recent developments in neuromodulation methods offer significant advantages and potential clinical benefits for a variety of disorders. Here we describe the current state of the art in neuromodulation methods, and some advances in brain-machine interfaces, describing the advantages and limitations of the clinical applications of each method. The future applications of these new methods and how they will shape the future of psychiatry and medicine, along with safety and ethical implications, are also discussed.

Electroacoustic stimulation: now and into the future.

Cochlear implants have provided hearing to hundreds of thousands of profoundly deaf people around the world. Recently, the eligibility criteria for cochlear implantation have been relaxed to include individuals who have some useful residual hearing. These recipients receive inputs from both electric and acoustic stimulation (EAS). Implant recipients who can combine these hearing modalities demonstrate pronounced benefit in speech perception, listening in background noise, and music appreciation over implant recipients that rely on electrical stimulation alone. The mechanisms bestowing this benefit are unknown, but it is likely that interaction of the electric and acoustic signals in the auditory pathway plays a role. Protection of residual hearing both during and following cochlear implantation is critical for EAS. A number of surgical refinements have been implemented to protect residual hearing, and the development of hearing-protective drug and gene therapies is promising for EAS recipients. This review outlines the current field of EAS, with a focus on interactions that are observed between these modalities in animal models. It also outlines current trends in EAS surgery and gives an overview of the drug and gene therapies that are clinically translatable and may one day provide protection of residual hearing for cochlear implant recipients.

Is the din really harmless? Long-term effects of non-traumatic noise on the adult auditory system.

People are increasingly being exposed to environmental noise from traffic, media and other sources that falls within and outside legal limits. Although such environmental noise is known to cause stress in the auditory system, it is still generally considered to be harmless. This complacency may be misplaced: even in the absence of cochlear damage, new findings suggest that environmental noise may progressively degrade hearing through alterations in the way sound is represented in the adult auditory cortex.

Perceptual basis of evolving Western musical styles.

The brain processes temporal statistics to predict future events and to categorize perceptual objects. These statistics, called expectancies, are found in music perception, and they span a variety of different features and time scales. Specifically, there is evidence that music perception involves strong expectancies regarding the distribution of a melodic interval, namely, the distance between two consecutive notes within the context of another. The recent availability of a large Western music dataset, consisting of the historical record condensed as melodic interval counts, has opened new possibilities for data-driven analysis of musical perception. In this context, we present an analytical approach that, based on cognitive theories of music expectation and machine learning techniques, recovers a set of factors that accurately identifies historical trends and stylistic transitions between the Baroque, Classical, Romantic, and Post-Romantic periods. We also offer a plausible musicological and cognitive interpretation of these factors, allowing us to propose them as data-driven principles of melodic expectation.

Music training for the development of auditory skills.

The effects of music training in relation to brain plasticity have caused excitement, evident from the popularity of books on this topic among scientists and the general public. Neuroscience research has shown that music training leads to changes throughout the auditory system that prime musicians for listening challenges beyond music processing. This effect of music training suggests that, akin to physical exercise and its impact on body fitness, music is a resource that tones the brain for auditory fitness. Therefore, the role of music in shaping individual development deserves consideration.

Trends in listening to personal stereos.

Long term use of personal stereo players (PSP) is now established as a potential risk to hearing health if exposure levels are not maintained at what are accepted as safe levels. Comparison of PSP user test results indicate that mean listening levels (L(Aeq)) have decreased from 86.1 dB in 2002/03 to 81.3 dB in 2008 and mean exposure levels (L(Aeq,8h)) have decreased from 79.8 dB to 74.7 dB over the same time period, in a user population whose mean age has increased from 23.6 years (SD = 5.7) to 26.0 years (SD = 10.5). This reduction in exposure level of 5 dB also means that the percentage of user population at risk of noise injury and subsequent hearing loss has decreased from 25% to 17% when judged by criterion commonly used for workplace occupational noise exposure standards.