Bimodal Stimulation for the Reduction of Tinnitus Using Vibration on the Skin

Tinnitus (ringing in the ears) affects 1 in 10 adults in the United States, often with damaging psychological consequences. Currently, there exists no cure for most forms of tinnitus. Recently, bimodal stimulation - the pairing of sounds with haptic stimulation - has shown efficacy in reducing the symptoms of tinnitus. Previous bimodal stimulation approaches have used electrical shocks on the tongue, a technique that requires daily in-person sessions at an audiologist's office. We here show that excellent results can be achieved wearing a wristband with multiple vibratory motors. Tones are played and the wristband correspondingly vibrates the wrist of the user at different spatial locations depending on the frequency of the tone. We compared the experimental group with a control group who listened to the tones but did not wear the wristband. The tone frequencies were centered on each user's tinnitus frequency and the tones were randomized both in frequency and duration. 45 participants with Tinnitus Functional Index (TFI) scores of 25 and above were tested. Results show a significantly greater reduction in TFI scores for the experimental group compared to the control. Importantly, with higher baseline severity we find larger differences between the experimental and control groups, revealing greater symptom improvement for those with severe tinnitus. The therapeutic approach of combining sounds with spatiallyand temporally-correlated vibrations on the wrist is found to be a simple, time-efficient, and effective procedure to lessen the symptoms of tinnitus.

Contralateral hearing aid use in adult cochlear implant recipients: retrospective analysis of auditory outcomes

OBJECTIVE

To investigate retrospectively the frequency of usage of bimodal stimulation among cochlear implant (CI) users, as well its clinical benefit relative to unilateral use.

DESIGN

All subjects had been monitored with the clinical Minimal Outcome Measurements test battery.

STUDY SAMPLES

103 adults with bilateral postlingual profound sensorineural hearing loss and unilateral CI use were extracted from the local database. These were divided into two groups: those who only used a CI and those who used bimodal stimulation.

RESULTS

The preoperative contralateral residual hearing in the bimodal group was significantly better than that of the CI-only group. In both groups, speech perception in quiet and in noise improved after CI, with no significant difference between postoperative unimodal conditions. For the bimodal group, an additional significant improvement was found for the bimodal condition compared to the unimodal.

CONCLUSION

Given the observed auditory benefit of bimodal stimulation in comparison to unimodal stimulation and given the finding that degree of residual hearing is not correlated with bimodal benefits, it is recommended to encourage CI recipients to continue contralateral HA use after CI. As a result of expanding CI criteria worldwide, the population of bimodal users is expected to grow in the near future.

Bimodal benefits in Mandarin-speaking cochlear implant users for music perception and tone recognition

BACKGROUND

Cochlear implant (CI) users have difficulty appreciating music and perceiving lexical tones in Mandarin Chinese. Wearing a hearing aid (HA) in the contralateral ear for bimodal hearing may provide additional benefits.

OBJECTIVES

To measure the bimodal benefits of music perception and tone recognition and to investigate the relationship between the two in Mandarin-speaking bimodal CI subjects.

MATERIALS AND METHODS

Sixteen Mandarin-speaking bimodal CI subjects (aged between 16 and 49 years) participated in the study. Music perception (pitch discrimination, melody discrimination and instrument identification) and lexical tone recognition were tested with electric stimulation (CI alone) or bimodal stimulation (CI + HA).

RESULTS

Subjects showed a significant bimodal benefit in tone recognition in quiet and noise, and in all music perception tests. The bimodal benefit for tone recognition in noise was significantly correlated with that of pitch discrimination thresholds and instrument identification scores.

CONCLUSION

Mandarin-speaking bimodal CI users achieved better music perception and tone recognition ability with CI + HA than with CI alone. The bimodal benefit of tone recognition was significantly correlated with that of music perception.

A bimodal extension of the Eriksen flanker task

The Eriksen flanker task is a traditional conflict paradigm for studying the influence of task-irrelevant information on the processing of task-relevant information. In this task, participants are asked to respond to a visual target item (e.g., a letter) that is flanked by task-irrelevant items (e.g., also letters). Responses are typically faster and more accurate when the task-irrelevant information is response-congruent with the visual target than when it is incongruent. Several researchers have attributed the starting point of this flanker effect to poor selective filtering at a perceptual level (e.g., spotlight models), which subsequently produces response competition at post-perceptual stages. The present study examined whether a flanker-like effect could also be established within a bimodal analog of the flanker task with auditory irrelevant letters and visual target letters, which must be processed along different processing routes. The results of two experiments revealed that a flanker-like effect is also present with bimodal stimuli. In contrast to the unimodal flanker task, however, the effect only emerged when flankers and targets shared the same letter name, but not when they were different letters mapped onto the same response. We conclude that the auditory flankers can influence the time needed to recognize visual targets but do not directly activate their associated responses.

Towards a Unified Testing Framework for Single-Sided Deafness Studies: A Consensus Paper

BACKGROUND

While hearing aids for a contralateral routing of signals (CROS-HA) and bone conduction devices have been the traditional treatment for single-sided deafness (SSD) and asymmetric hearing loss (AHL), in recent years, cochlear implants (CIs) have increasingly become a viable treatment choice, particularly in countries where regulatory approval and reimbursement schemes are in place. Part of the reason for this shift is that the CI is the only device capable of restoring bilateral input to the auditory system and hence of possibly reinstating binaural hearing. Although several studies have independently shown that the CI is a safe and effective treatment for SSD and AHL, clinical outcome measures in those studies and across CI centers vary greatly. Only with a consistent use of defined and agreed-upon outcome measures across centers can high-level evidence be generated to assess the safety and efficacy of CIs and alternative treatments in recipients with SSD and AHL.

METHODS

This paper presents a comparative study design and minimum outcome measures for the assessment of current treatment options in patients with SSD/AHL. The protocol was developed, discussed, and eventually agreed upon by expert panels that convened at the 2015 APSCI conference in Beijing, China, and at the CI 2016 conference in Toronto, Canada.

RESULTS

A longitudinal study design comparing CROS-HA, BCD, and CI treatments is proposed. The recommended outcome measures include (1) speech in noise testing, using the same set of 3 spatial configurations to compare binaural benefits such as summation, squelch, and head shadow across devices; (2) localization testing, using stimuli that rove in both level and spectral content; (3) questionnaires to collect quality of life measures and the frequency of device use; and (4) questionnaires for assessing the impact of tinnitus before and after treatment, if applicable.

CONCLUSION

A protocol for the assessment of treatment options and outcomes in recipients with SSD and AHL is presented. The proposed set of minimum outcome measures aims at harmonizing assessment methods across centers and thus at generating a growing body of high-level evidence for those treatment options.

Frequency-dependent loudness balancing in bimodal cochlear implant users

Conclusion In users of a cochlear implant (CI) and a hearing aid (HA) in contralateral ears, frequency-dependent loudness balancing between devices did, on average, not lead to improved speech understanding as compared to broadband balancing. However, nine out of 15 bimodal subjects showed significantly better speech understanding with either one of the fittings. Objectives Sub-optimal fittings and mismatches in loudness are possible explanations for the large individual differences seen in listeners using bimodal stimulation. Methods HA gain was adjusted for soft and loud input sounds in three frequency bands (0-548, 548-1000, and >1000 Hz) to match loudness with the CI. This procedure was compared to a simple broadband balancing procedure that reflected current clinical practice. In a three-visit cross-over design with 4 weeks between sessions, speech understanding was tested in quiet and in noise and questionnaires were administered to assess benefit in real world. Results Both procedures resulted in comparable HA gains. For speech in noise, a marginal bimodal benefit of 0.3 ± 4 dB was found, with large differences between subjects and spatial configurations. Speech understanding in quiet and in noise did not differ between the two loudness balancing procedures.

Podokinetic circular vection: characteristics and interaction with optokinetic circular vection

Stabilising horizontal body orientation in space without sight on a rotating platform by holding to a stationary structure and circular 'treadmill' stepping in the opposite direction can elicit an illusion of self-turning in space (Bles and Kapteyn in Agressologie 18:325-328, 1977). Because this illusion is analogous to the well-known illusion of optokinetic circular vection (oCV), we call it 'podokinetic circular vection' (pCV) here. Previous studies using eccentric stepping on a path tangential to the rotation found that pCV was always contraversive relative to platform rotation. In contrast, when our subjects stepped at the centre of rotation about their vertical axis, we observed an inverted, ipsiversive pCV as a reproducible trait in many of our subjects. This ipCV occurred at the same latency as the pCV of subjects reporting the actually expected contraversive direction, but had lower gain. In contrast to pCV, the nystagmus accompanying circular treadmill stepping had the same direction in all individuals (slow phase in the direction of platform motion). The direction of an individual's pCV predicted the characteristics of the CV resulting from combined opto- and podokinetic stimulation (circular treadmill stepping while viewing a pattern rotating together with the platform): in individuals with contraversive pCV, latency shortened and both gain and felt naturalness increased in comparison with pure oCV, whereas the opposite (longer latency, reduced gain and naturalness) occurred in individuals with ipCV. Taken together, the reproducibility of ipCV, the constant direction of nystagmus and the fact that pCV direction predicts the outcome of combined stimulation suggest that ipCV is an individual trait of many subjects during compensatory stepping at the centre of rotation. A hypothetical model is presented of how ipCV possibly could arise.

Role of bimodal stimulation for auditory-perceptual skills development in children with a unilateral cochlear implant

This is a prospective randomised study that evaluated the differences arising from a bimodal stimulation compared to a monaural electrical stimulation in deaf children, particularly in terms of auditory-perceptual skills development. We enrolled 39 children aged 12 to 36 months, suffering from severe-to-profound bilateral sensorineural hearing loss with residual hearing on at least one side. All were unilaterally implanted: 21 wore only the cochlear implant (CI) (unilateral CI group), while the other 18 used the CI and a contralateral hearing aid at the same time (bimodal group). They were assessed with a test battery designed to appraise preverbal and verbal auditory-perceptual skills immediately before and 6 and 12 months after implantation. No statistically significant differences were observed between groups at time 0, while at 6 and 12 months children in the bimodal group had better scores in each test than peers in the unilateral CI group. Therefore, although unilateral deafness/hearing does not undermine hearing acuity in normal listening, the simultaneous use of a CI and a contralateral hearing aid (binaural hearing through a bimodal stimulation) provides an advantage in terms of acquisition of auditory-perceptual skills, allowing children to achieve the basic milestones of auditory perception faster and in greater number than children with only one CI. Thus, "keeping awake" the contralateral auditory pathway, albeit not crucial in determining auditory acuity, guarantees benefits compared with the use of the implant alone. These findings provide initial evidence to establish shared guidelines for better rehabilitation of patients undergoing unilateral cochlear implantation, and add more evidence regarding the correct indications for bilateral cochlear implantation.

Quality of life in bimodal hearing users (unilateral cochlear implants and contralateral hearing aids)

The main objective was to evaluate the bimodal self-rated benefits on auditory performance under real conditions and the quality of life in two groups of cochlear-implanted adults, with or without a contralateral hearing aid. The secondary objective was to investigate correlations between the use of a hearing aid and residual hearing on the non-implanted ear. This retrospective study was realized between 2000 and 2010 in two referral centers. A population of 183 postlingually deaf adults, implanted with a cochlear experience superior to 6 months, was selected. The Speech, Spatial, and other Qualities of Hearing Scale were administered to evaluate the auditory performances, and the Nijmegen Cochlear Implant Questionnaire to evaluate the quality of life. The population was divided into two groups: a group with unilateral cochlear implants (Cochlear Implant-alone, n = 54), and a bimodal group with a cochlear implant and a contralateral hearing aid (n = 62). Both groups were similar in terms of auditory deprivation duration, duration of cochlear implant use, and pure-tone average on the implanted ear. There was a significant difference in terms of pure-tone average on low and low-to-mid frequencies on the non-implanted ear. The scores on both questionnaires showed an improvement in the basic sound perception and quality of social activities for the bimodal group. The results suggest that the bimodal stimulation (cochlear implant and contralateral hearing aid) improved auditory perception in quiet and the quality of life domain of social activities.

Speech recognition performance in children with cochlear implants using bimodal stimulation

Cochlear implantees have considerably good speech understanding abilities in quiet surroundings. But, ambient noise poses significant difficulties in understanding speech for these individuals. Bimodal stimulation is still not used by many Indian implantees in spite of reports that bimodal stimulation is beneficial for speech understanding in noise as compared to cochlear implant alone and also prevents auditory deprivation in the un-implanted ear. The aim of the study is to evaluate the benefits of bimodal stimulation in children in an Indian cochlear implant clinic. A group of 14 children who have been using cochlear implants served as subjects in this study. They were fitted with advanced digital hearing aids in their un-implanted ears to provide bimodal stimulation. Results revealed that bimodal stimulation did not bring greater change in speech scores in quiet surroundings but have shown a noticeable improvement in noisy ambience. Hence the present study suggests that bimodal stimulation would benefit children with cochlear implants especially in adverse listening conditions.