The AB-York crescent of sound: an apparatus for assessing spatial-listening skills in children and adults

Integrated bimodal fitting and binaural streaming technology outcomes for unilateral cochlear implant users

OBJECTIVE

Adults typically receive only one cochlear implant (CI) due to cost constraints, with a contralateral hearing aid recommended when there is aidable hearing. Standard hearing aids differ from a CI in terms of processing strategy and function as a separate entity, requiring the user to integrate the disparate signals. Integrated bimodal technology has recently been introduced to address this challenge. The aim of the study was to investigate the performance of unilateral CI users with and without an integrated bimodal fitting and determine whether binaural streaming technology offers additional benefit.

STUDY SAMPLE

Twenty-six CI users using integrated bimodal technology.

DESIGN

Repeated measures where outcomes and user experience were assessed using a functional test battery more representative of real life listening (speech perception in noise tests, localisation test, tracking test) and the speech, spatial and qualities-of-hearing scale (SSQ).

RESULTS

Bimodal outcomes were significantly better than for CI alone. Speech perception in noise improvements ranged from 1.4 dB to 3.5 dB depending on the location of speech and noise. The localisation and tracking tests, and the SSQ also showed significant improvements. Binaural streaming offered additional improvement (1.2 dB to 6.1 dB on the different speech tests).

CONCLUSIONS

Integrated bimodal and binaural streaming technology improved the performance of unilateral CI users.

Comparison of an Implantable Middle Ear Microphone and Conventional External Microphone for Cochlear Implants: A Clinical Feasibility Study

OBJECTIVES

All commercially available cochlear implant (CI) systems use an external microphone and sound processor; however, external equipment carries lifestyle limitations. Although totally implantable devices using subcutaneous microphones have been developed, these are compromised by problems with soft tissue sound attenuation, feedback, and intrusive body noise. This in vivo pilot study evaluates a middle ear microphone (MEM) that aims to overcome these issues and compares hearing performance with that of an external CI microphone.

DESIGN

Six adult participants with an existing CI were implanted with a temporary MEM in the contralateral ear. Signals from the MEM were routed via a percutaneous plug and cable to the CI sound processor. Testing was performed in the CI microphone and MEM conditions using a range of audiometric assessments, which were repeated across four visits.

RESULTS

Performance of the MEM did not differ significantly from that of the CI on the assessments of Auditory Speech Sounds Evaluation loudness scaling at either 250 or 1000 Hz, or in the accuracy of repeating keywords presented at 70 dB. However, the MEM had significantly poorer aided sound-field thresholds, particularly at higher frequencies (≥4000 Hz), and significantly poorer performance on Arthur Boothroyd words presented at 55 dB, compared with the CI.

CONCLUSION

In this pilot study, the MEM showed comparable performance to that of an external CI microphone across some audiometric assessments. However, performance with the MEM was poorer than the CI in soft-level speech (55 dB) and at higher frequencies. As such, the benefits of MEM need to be considered against the compromises in hearing performance. However, with future development, MEM is a potentially promising technology.

Evaluating Spatial Hearing Using a Dual-Task Approach in a Virtual-Acoustics Environment

Spatial hearing is critical for communication in everyday sound-rich environments. It is important to gain an understanding of how well users of bilateral hearing devices function in these conditions. The purpose of this work was to evaluate a Virtual Acoustics (VA) version of the Spatial Speech in Noise (SSiN) test, the SSiN-VA. This implementation uses relatively inexpensive equipment and can be performed outside the clinic, allowing for regular monitoring of spatial-hearing performance. The SSiN-VA simultaneously assesses speech discrimination and relative localization with changing source locations in the presence of noise. The use of simultaneous tasks increases the cognitive load to better represent the difficulties faced by listeners in noisy real-world environments. Current clinical assessments may require costly equipment which has a large footprint. Consequently, spatial-hearing assessments may not be conducted at all. Additionally, as patients take greater control of their healthcare outcomes and a greater number of clinical appointments are conducted remotely, outcome measures that allow patients to carry out assessments at home are becoming more relevant. The SSiN-VA was implemented using the 3D Tune-In Toolkit, simulating seven loudspeaker locations spaced at 30° intervals with azimuths between -90° and +90°, and rendered for headphone playback using the binaural spatialization technique. Twelve normal-hearing participants were assessed to evaluate if SSiN-VA produced patterns of responses for relative localization and speech discrimination as a function of azimuth similar to those previously obtained using loudspeaker arrays. Additionally, the effect of the signal-to-noise ratio (SNR), the direction of the shift from target to reference, and the target phonetic contrast on performance were investigated. SSiN-VA led to similar patterns of performance as a function of spatial location compared to loudspeaker setups for both relative localization and speech discrimination. Performance for relative localization was significantly better at the highest SNR than at the lowest SNR tested, and a target shift to the right was associated with an increased likelihood of a correct response. For word discrimination, there was an interaction between SNR and word group. Overall, these outcomes support the use of virtual audio for speech discrimination and relative localization testing in noise.

Instant improvement in monaural spatial hearing abilities through cognitive feedback

Several studies report that sound localization performance of acute and chronic monauralized normal-hearing listeners can improve through training. Typically, training sessions are administered daily for several days or weeks. While this intensive training is effective, it may also be that monaural localization abilities improve instantly after providing explicit top-down information about the direction dependent change in timbre and level. The aim of the present study was to investigate whether cognitive feedback (i.e., top-down information) could instantly improve sound localization in naive acutely monauralized listeners. Forty-three normal-hearing listeners (experimental group), divided over five different centers, were tested. Two control groups, consisting of, respectively, nine and eleven normal-hearing listeners, were tested in one center. Broadband sounds (0.5-20 kHz) were presented from visible loudspeakers, positioned in azimuth (- 90° to 90°). Participants in the experimental group received explicit information about the noticeable difference in timbre and the poor localization in the monauralized listening condition, resulting in an instant improvement in sound localization abilities. With subsequent roving of stimulus level (20 dB), sound localization performance deteriorated immediately. The reported improvement is related to the context of the localization test. The results provide important implications for studies investigating sound localization in a clinical setting, especially during closed-set testing, and indicate the importance of top-down information.

A Compact Two-Loudspeaker Virtual Sound Reproduction System for Clinical Testing of Spatial Hearing With Hearing-Assistive Devices

Exciting developments in hearing aid and cochlear implant technology for linking signal processing across the ears have improved spatial hearing outcomes. This has resulted in an increased emphasis on clinical assessment of the spatial hearing abilities of hearing-assistive device users. Effective assessment of spatial hearing currently requires a large and costly loudspeaker array system, housed in a heavily acoustically treated testing room. This imposes economic and logistical constraints that limit proliferation of array systems, particularly in developing nations. Despite their size and cost, the ability of current clinical array systems to reproduce realistic spatial sound fields is limited, which substantially reduces the range of realistic acoustic scenes that can be used for diagnostic testing. We propose an alternative low-cost, compact virtual acoustics system with just two loudspeakers. This system uses crosstalk cancelation to reproduce pressure signals at the device microphones that match those for real-world sound sources. Furthermore, in contrast to clinical array systems, the system can adapt to different room acoustics, removing the requirement for a heavily acoustically treated testing environment. We conducted a proof-of-concept study in two stages: in the first, we evaluated the physical performance of the system for a stationary listener in anechoic conditions and in a small audiological testing booth with moderate acoustic treatment. To do this, a head and torso simulator was fitted with specially adapted hearing-assistive devices that allowed direct access to the microphone signals. These microphone signals were compared for real and virtual sound sources at numerous source locations. In the second stage, we quantified the system’s robustness to head rotations with and without the system adapting for head position. In the stationary case, the system was found to be highly effective at reproducing signals, such as speech, at all tested source locations. When head rotation was added, it performed well for rotations of up to 2°, even without adapting. However, performance improved markedly for larger rotations when the system adapted. These findings suggest that a compact, low-cost virtual acoustics system can give wider access to advanced and ecologically valid audiological testing, which could substantially improve clinical assessment of hearing-assistive device users.

Short-term outcomes of cochlear implantation for single-sided deafness compared to bone conduction devices and contralateral routing of sound hearing aids-Results of a Randomised controlled trial (CINGLE-trial)

Single-sided deafness (SSD) leads to difficulties with speech perception in noise, sound localisation, and sometimes tinnitus. Current treatments (Contralateral Routing of Sound hearing aids (CROS) and Bone Conduction Devices (BCD)) do not sufficiently overcome these problems. Cochlear implants (CIs) may help. Our aim was to evaluate these treatments in a Randomised Controlled Trial (RCT). Adult SSD patients were randomised using a web-based randomisation tool into one of three groups: CI; trial period of 'first BCD, then CROS'; trial period of 'first CROS, then BCD'. After these trial periods, patients opted for BCD, CROS, or No treatment. The primary outcome was speech perception in noise (directed from the front (S0N0)). Secondary outcomes were speech perception in noise with speech directed to the poor ear and noise to the better ear (SpeNbe) and vice versa (SbeNpe), sound localisation, tinnitus burden, and disease-specific quality of life (QoL). We described results at baseline (unaided situation) and 3 and 6 months after device activation. 120 patients were randomised. Seven patients did not receive the allocated intervention. The number of patients per group after allocation was: CI (n = 28), BCD (n = 25), CROS (n = 34), and No treatment (n = 26). In S0N0, the CI group performed significantly better when compared to baseline, and when compared to the other groups. In SpeNbe, there was an advantage for all treatment groups compared to baseline. However, in SbeNpe, BCD and CROS groups performed worse compared to baseline, whereas the CI group improved. Only in the CI group sound localisation improved and tinnitus burden decreased. In general, all treatment groups improved on disease-specific QoL compared to baseline. This RCT demonstrates that cochlear implantation for SSD leads to improved speech perception in noise, sound localisation, tinnitus burden, and QoL after 3 and 6 months of follow-up. For most outcome measures, CI outperformed BCD and CROS. Trial registration: Netherlands Trial Register (www.trialregister.nl): NTR4580, CINGLE-trial.

Development and Critical Evaluation of a Condition-Specific Preference-Based Measure Sensitive to Binaural Hearing in Adults: The York Binaural Hearing-Related Quality-of-Life System

OBJECTIVES

The widely-used generic preference-based measures of health-related quality of life-the EuroQol Descriptive System (EQ-5D) and the Health Utilities Index (HUI3)-are limited in their response to technologies that improve hearing. The EQ-5D lacks construct validity for hearing, while the HUI3 is restricted by a ceiling effect and by using speech reception as the only evidence of the ability to hear. Consequently, neither measure consistently registers benefits from binaural hearing, such as those from bilateral versus unilateral cochlear implantation. The objectives were to test whether informants value binaural hearing, to develop a condition-specific preference-based measure sensitive to binaural hearing, to assess the psychometric properties of the new instrument, and to determine whether it meets requirements for informing judgments of cost-effectiveness: does it measure greater gains than do the generic preference-based measures, while avoiding exaggerating losses, and displaying sensitivity to side effects?

DESIGN

Three levels of function, ranging from no difficulty to great difficulty, were defined on each of three dimensions where listening is easier or more successful when hearing is binaural rather than monaural: perception of speech in spatially separated noise, localization of sounds, and effort and fatigue. Informants (N = 203) valued the 27 combinations of levels and dimensions in a time trade-off task with a 10-year time frame to provide a value of binaural-related quality of life ("binaural utility") for each combination. A questionnaire was compiled to allow respondents to report their level of function on each dimension so that a value of binaural utility could be assigned to them. The questionnaire and the age-standardized valuations constitute The York Binaural Hearing-Related Quality-of-Life System (YBHRQL). Adult users of unilateral implants (N = 8), bilateral implants (N = 11), or bimodal aiding (N = 9) undertook performance tests of spatial listening and completed the HUI3, EQ-5D, and Speech, Spatial, and Qualities of Hearing (SSQ) questionnaires. They completed the YBHRQL questionnaire 24 and 38 mo later.

RESULTS

Despite long intervals between measurements, the YBHRQL demonstrated desirable psychometric properties: good construct validity evidenced by significant correlations with performance measures and the SSQ index; a greater ability than the EQ-5D or HUI3 to distinguish unilateral, bimodal, and bilateral listening; and good reproducibility. The YBHRQL did not exaggerate losses of utility but was insensitive to a potential side effect of implantation (pain/discomfort). It measured a gain in utility from bilateral compared with unilateral implantation (median = 0.11, interquartile range, 0.03 to 0.16) that was greater than the gain measured by the EQ-5D (0.00, 0.00 to 0.00) but not the HUI3 (0.00, 0.00 to 0.17).

CONCLUSIONS

The YBHRQL summarizes the contribution of binaural hearing to quality of life by combining the functional status of a listener with the preferences of independent informants. It would be an efficient clinical outcome measure. In addition, if used alongside the EQ-5D or HUI3, it would provide evidence which could beneficially modulate confidence in the cost-effectiveness of interventions. Further research on its sensitivity to side effects, and on the size of the gains in utility which it measures, is needed to determine whether it could stand alone to inform resource-allocation decisions.

Remote Microphone Hearing Aid Use Improves Classroom Listening, Without Adverse Effects on Spatial Listening and Attention Skills, in Children With Auditory Processing Disorder: A Randomised Controlled Trial

BACKGROUND

Children with Auditory Processing Disorder (APD) often have poor auditory processing skills in the presence of normal peripheral hearing. These children have worse listening-in-noise skills compared to typically developing peers, while other commonly reported symptoms include poor attention and distractibility. One of the management strategies for children with APD is the use of Remote Microphone Hearing Aids (RMHAs), which can help improve the signal-to-noise ratio in the child's ears. The aim of this randomised controlled trial was to examine whether RMHAs improved classroom listening in children with APD, and to further test their effects on children's listening-in-noise and attention skills following a 6-month intervention.

METHODS

Twenty-six children diagnosed with APD, aged 7-12, in primary mainstream education, were randomised into the intervention (N = 13) and control group (N = 13). The primary outcome measure was the Listening Inventory for Education - Revised questionnaire, completed by children to assess their listening using RMHAs under several acoustically challenging situations in the classroom. Secondary outcome measures included the Listening in Spatialised Noise - Sentences test, assessing speech-in-noise perception and spatial listening, and the Test of Everyday Attention for Children, assessing different types of attention skills. Tests were conducted in unaided conditions. Mixed analysis of variance was used to analyse the data. The clinical trial was registered at clinicaltrials.gov (unique identifier: NCT02353091).

RESULTS

The questionnaire scores of self-reported listening skills in the classroom significantly improved in the intervention group after 3, MD = 7.31, SE = 2.113, p = 0.014, and after 6 months, M = 5.00, SE = 1.468, p = 0.016. The behavioural measures of listening-in-noise and attention did not significantly change.

CONCLUSION

Use of RMHAs improves classroom listening, evidenced by the results of the questionnaire analysis, while a 6-month use did not have adverse effects on unaided spatial listening or attention skills.

Objective and Subjective Measures of Simultaneous vs Sequential Bilateral Cochlear Implants in Adults: A Randomized Clinical Trial

Importance

To date, no randomized clinical trial on the comparison between simultaneous and sequential bilateral cochlear implants (BiCIs) has been performed.

Objective

To investigate the hearing capabilities and the self-reported benefits of simultaneous BiCIs compared with those of sequential BiCIs.

Design, Setting, and Participants

A multicenter randomized clinical trial was conducted between January 12, 2010, and September 2, 2012, at 5 tertiary referral centers among 40 participants eligible for BiCIs. Main inclusion criteria were postlingual severe to profound hearing loss, age 18 to 70 years, and a maximum duration of 10 years without hearing aid use in both ears. Data analysis was conducted from May 24 to June 12, 2016.

Interventions

The simultaneous BiCI group received 2 cochlear implants during 1 surgical procedure. The sequential BiCI group received 2 cochlear implants with an interval of 2 years between implants.

Main Outcomes and Measures

First, the results 1 year after receiving simultaneous BiCIs were compared with the results 1 year after receiving sequential BiCIs. Second, the results of 3 years of follow-up for both groups were compared separately. The primary outcome measure was speech intelligibility in noise from straight ahead. Secondary outcome measures were speech intelligibility in noise from spatially separated sources, speech intelligibility in silence, localization capabilities, and self-reported benefits assessed with various hearing and quality of life questionnaires.

Results

Nineteen participants were randomized to receive simultaneous BiCIs (11 women and 8 men; median age, 52 years [interquartile range, 36-63 years]), and another 19 participants were randomized to undergo sequential BiCIs (8 women and 11 men; median age, 54 years [interquartile range, 43-64 years]). Three patients did not receive a second cochlear implant and were unavailable for follow-up. Comparable results were found 1 year after simultaneous or sequential BiCIs for speech intelligibility in noise from straight ahead (difference, 0.9 dB [95% CI, -3.1 to 4.4 dB]) and all secondary outcome measures except for localization with a 30° angle between loudspeakers (difference, -10% [95% CI, -20.1% to 0.0%]). In the sequential BiCI group, all participants performed significantly better after the BiCIs on speech intelligibility in noise from spatially separated sources and on all localization tests, which was consistent with most of the participants' self-reported hearing capabilities. Speech intelligibility-in-noise results improved in the simultaneous BiCI group up to 3 years following the BiCIs.

Conclusions and Relevance

This study shows comparable objective and subjective hearing results 1 year after receiving simultaneous BiCIs and sequential BiCIs with an interval of 2 years between implants. It also shows a significant benefit of sequential BiCIs over a unilateral cochlear implant. Until 3 years after receiving simultaneous BiCIs, speech intelligibility in noise significantly improved compared with previous years.

Trial Registration

trialregister.nl Identifier: NTR1722.

Long-term use benefits of personal frequency-modulated systems for speech in noise perception in patients with stroke with auditory processing deficits: a non-randomised controlled trial study

OBJECTIVES

Approximately one in five stroke survivors suffer from difficulties with speech reception in noise, despite normal audiometry. These deficits are treatable with personal frequency-modulated systems (FMs). This study aimed to evaluate long-term benefits in speech reception in noise, after daily 10-week use of personal FMs, in non-aphasic patients with stroke with auditory processing deficits.

DESIGN

This was a prospective non-randomised controlled trial study. Patients were allocated to an intervention care group or standard care subjects group according to their willingness to use the intervention or not.

SETTING

Tertiary care setting.

PARTICIPANTS

Nine non-aphasic subjects with ischaemic stroke, normal/near-normal audiometry and auditory processing deficits and with reported difficulties understanding speech in background noise were recruited in the subacute stroke stage (3-12 months after stroke).

INTERVENTIONS

Four patients (intervention care subjects) used the FMs in their daily life over 10 weeks. Five patients (standard care subjects) received standard care.

PRIMARY OUTCOME MEASURES

All subjects were tested at baseline (visit 1) and 10 weeks later (visit 2) on a sentences in noise test with the FMs (aided) and without the FMs (unaided).

RESULTS

Speech reception thresholds showed clinically and statistically significant improvements in intervention but not in standard care subjects at 10 weeks in aided and unaided conditions.

CONCLUSIONS

10-week use of FMs by adult patients with stroke may lead to benefits in unaided speech in noise perception. Our findings may indicate auditory plasticity type changes and require further investigation.

TRIAL REGISTRATION NUMBER

Pre-results; NCT02889107.

Contralateral acoustic hearing aid use in adult unilateral cochlear implant recipients: Current provision, practice, and clinical experience in the UK

OBJECTIVES

The study surveyed practising cochlear implant (CI) audiologists with the aim of: (1) characterizing UK clinical practice around the management and fitting of a contralateral hearing aid (HA) in adult unilateral CI users ('bimodal aiding'); (2) identifying factors that may limit the provision of bimodal aiding; and (3) ascertaining the views of audiologists on bimodal aiding.

METHODS

An online survey was distributed to audiologists working at the 20 centres providing implantation services to adults in the UK.

RESULTS

Responses were received from 19 of the 20 centres. The majority of centres reported evaluating HAs as part of the candidacy assessment for cochlear implantation. However, a majority also indicated that they do not take responsibility for the contralateral HA following implantation, despite identifying few practical limiting factors. Bimodal aiding was viewed as more beneficial than wearing the implant alone, with most respondents actively encouraging bimodal listening where possible. Respondents reported that fitting bimodal devices to take account of each other's settings was potentially more beneficial than independently fit devices, but such sympathetic fitting was not routine practice in any centre.

DISCUSSION

The results highlight some potential inconsistencies in the provision of bimodal aiding across the UK as reported by practising audiologists. The views of audiologists about what is best practice appear to be at odds with the nature and structure of the services currently offered.

CONCLUSION

Stronger evidence that bimodal aiding can be beneficial for UK patients would be required in order for service providers to justify the routine provision of bimodal aiding and to inform guidelines to shape routine clinical practice.

Auditory rehabilitation after stroke: treatment of auditory processing disorders in stroke patients with personal frequency-modulated (FM) systems

PURPOSE

Auditory disability due to impaired auditory processing (AP) despite normal pure-tone thresholds is common after stroke, and it leads to isolation, reduced quality of life and physical decline. There are currently no proven remedial interventions for AP deficits in stroke patients. This is the first study to investigate the benefits of personal frequency-modulated (FM) systems in stroke patients with disordered AP.

METHODS

Fifty stroke patients had baseline audiological assessments, AP tests and completed the (modified) Amsterdam Inventory for Auditory Disability and Hearing Handicap Inventory for Elderly questionnaires. Nine out of these 50 patients were diagnosed with disordered AP based on severe deficits in understanding speech in background noise but with normal pure-tone thresholds. These nine patients underwent spatial speech-in-noise testing in a sound-attenuating chamber (the "crescent of sound") with and without FM systems.

RESULTS

The signal-to-noise ratio (SNR) for 50% correct speech recognition performance was measured with speech presented from 0° azimuth and competing babble from ±90° azimuth. Spatial release from masking (SRM) was defined as the difference between SNRs measured with co-located speech and babble and SNRs measured with spatially separated speech and babble. The SRM significantly improved when babble was spatially separated from target speech, while the patients had the FM systems in their ears compared to without the FM systems.

CONCLUSIONS

Personal FM systems may substantially improve speech-in-noise deficits in stroke patients who are not eligible for conventional hearing aids. FMs are feasible in stroke patients and show promise to address impaired AP after stroke. Implications for Rehabilitation This is the first study to investigate the benefits of personal frequency-modulated (FM) systems in stroke patients with disordered AP. All cases significantly improved speech perception in noise with the FM systems, when noise was spatially separated from the speech signal by 90° compared with unaided listening. Personal FM systems are feasible in stroke patients, and may be of benefit in just under 20% of this population, who are not eligible for conventional hearing aids.

Simultaneous Assessment of Speech Identification and Spatial Discrimination: A Potential Testing Approach for Bilateral Cochlear Implant Users?

With increasing numbers of children and adults receiving bilateral cochlear implants, there is an urgent need for assessment tools that enable testing of binaural hearing abilities. Current test batteries are either limited in scope or are of an impractical duration for routine testing. Here, we report a behavioral test that enables combined testing of speech identification and spatial discrimination in noise. In this task, multitalker babble was presented from all speakers, and pairs of speech tokens were sequentially presented from two adjacent speakers. Listeners were required to identify both words from a closed set of four possibilities and to determine whether the second token was presented to the left or right of the first. In Experiment 1, normal-hearing adult listeners were tested at 15° intervals throughout the frontal hemifield. Listeners showed highest spatial discrimination performance in and around the frontal midline, with a decline at more eccentric locations. In contrast, speech identification abilities were least accurate near the midline and showed an improvement in performance at more lateral locations. In Experiment 2, normal-hearing listeners were assessed using a restricted range of speaker locations designed to match those found in clinical testing environments. Here, speakers were separated by 15° around the midline and 30° at more lateral locations. This resulted in a similar pattern of behavioral results as in Experiment 1. We conclude, this test offers the potential to assess both spatial discrimination and the ability to use spatial information for unmasking in clinical populations.

The effect of early auditory experience on the spatial listening skills of children with bilateral cochlear implants

OBJECTIVES

Both electrophysiological and behavioural studies suggest that auditory deprivation during the first months and years of life can impair listening skills. Electrophysiological studies indicate that 3½ years may be a critical age for the development of symmetrical cortical responses in children using bilateral cochlear implants. This study aimed to examine the effect of auditory experience during the first 3½ years of life on the behavioural spatial listening abilities of children using bilateral cochlear implants, with reference to normally hearing children. Data collected during research and routine clinical testing were pooled to compare the listening skills of children with bilateral cochlear implants and different periods of auditory deprivation.

METHODS

Children aged 4-17 years with bilateral cochlear implants were classified into three groups. Children born profoundly deaf were in the congenital early bilateral group (received bilateral cochlear implants aged ≤3½ years, n=28) or congenital late bilateral group (received first implant aged ≤3½ years and second aged >3½ years, n=38). Children with some bilateral acoustic hearing until the age of 3½ years, who subsequently became profoundly deaf and received bilateral cochlear implants, were in the acquired/progressive group (n=16). There were 32 children in the normally hearing group. Children completed tests of sound-source localization and spatial release from masking (a measure of the ability to use both ears to understand speech in noise).

RESULTS

The acquired/progressive group localized more accurately than both groups of congenitally deaf children (p<0.05). All three groups of children with cochlear implants showed similar spatial release from masking. The normally hearing group localized more accurately than all groups with bilateral cochlear implants and displayed more spatial release from masking than the congenitally deaf groups on average (p<0.05).

CONCLUSION

Children with bilateral cochlear implants and early experience of acoustic hearing showed more accurate localization skills, on average, than children born profoundly deaf.

CINGLE-trial: cochlear implantation for siNGLE-sided deafness, a randomised controlled trial and economic evaluation

Background

Individuals with single-sided deafness (SSD) have problems with speech perception in noise, localisation of sounds and with communication and social interaction in their daily life. Current treatment modalities (Contralateral Routing of Sound systems [CROS] and Bone Conduction Devices [BCD]) do not restore binaural hearing. Based on low level of evidence studies, CROS and BCD do not improve speech perception in noise or sound localisation. In contrast, cochlear implantation (CI) may overcome the limitations of CROS and BCD, as binaural input can be restored. Promising results have previously been achieved on speech perception in noise, sound localisation, tinnitus and quality of life.

Methods and design

A single-center Randomised Controlled Trial (RCT) was designed to compare all treatment strategies for SSD. One hundred and twenty adult single-sided deaf patients (duration of deafness >3 months and maximum 10 years; pure tone average at 0.5, 1, 2, 4 kHz, deaf ear: threshold equal to or more than 70 dB, better ear: threshold of maximum 30 dB) will be included in this trial and randomised to CI, ‘first BCD, then CROS’ or ‘first CROS, then BCD’-groups. After the trial period, patients in the two latter groups may choose with which treatment option they continue. Outcomes of interest are speech perception in noise, sound localization, tinnitus and quality of life. These outcomes will be measured during a baseline visit and at follow up visits, which will take place at 6, 12, 18, 24, 36, 48 and 60 months after onset of treatment. Furthermore, an economic evaluation will be performed and adverse events will be monitored.

Discussion

This RCT allows for a comparison between the two current treatment modalities for single-sided deafness and a new promising treatment strategy, CI, on a range of health outcomes: speech perception in noise, sound localization, tinnitus and quality of life. Additionally, we will be able to answer the question if the additional costs of CI are justified by increased benefits, when compared to current treatment strategies. This study will inform health policy makers with regard to reimbursement of CI.

Trial registration

Netherlands Trial Register (www.trialregister.nl): NTR4580.

Validation of the U-STARR with the AB-York Crescent of Sound, a New Instrument to Evaluate Speech Intelligibility in Noise and Spatial Hearing Skills

The Advanced Bionics® (AB)-York crescent of sound is a new test setup that comprises speech intelligibility in noise and localization tests that represent everyday listening situations. One of its tests is the Sentence Test with Adaptive Randomized Roving levels (STARR) with sentences and noise both presented from straight ahead. For the Dutch population, we adopted the AB-York setup and replaced the English sentences with a validated set of Dutch sentences. The Dutch version of the STARR is called the Utrecht-STARR (U-STARR). This study primarily assesses the validity and reliability of the U-STARR compared to the Plomp test, which is the current Dutch gold standard for speech-in-noise testing. The outcome of both tests is a speech reception threshold in noise (SRTn). Secondary outcomes are the SRTn measured with sounds from spatially separated sources (SISSS) as well as sound localization capability. We tested 29 normal-hearing adults and 18 postlingually deafened adult patients with unilateral cochlear implants (CI). This study shows that the U-STARR is adequate and reliable and seems better suited for severely hearing-impaired persons than the conventional Plomp test. Further, CI patients have poor spatial listening skills, as demonstrated with the AB-York test.

Changes in children's speech discrimination and spatial release from masking between 2 and 4 years after sequential cochlear implantation

OBJECTIVE

To document changes in speech reception thresholds (SRTs) and spatial release from masking (SRM) for sequentially implanted children at 2 and 4 years after they received their second cochlear implant (CI2).

METHODS

Participants were 17 children who consistently used two sequentially implanted and optimally programmed CIs. SRTs were measured monaurally in quiet and binaurally in noise using the adaptive McCormick toy discrimination test. Speech signals were presented from 0° azimuth and noise from 0°, +90° or  -90° azimuth. SRM was calculated from SRTs in noise. Measurements were made at 2 and 4 year post-CI2.

RESULTS

There were significant improvements over time in SRTs in quiet, SRTs in noise and SRM. SRTs in quiet improved more for CI2 than for the first implant (CI1). SRTs in noise and SRM improved more when noise was presented closest to CI1 than when closest to CI2. Performance became more symmetrical over time.

DISCUSSION

Despite prolonged periods of unilateral auditory deprivation sequentially implanted children exhibited continued improvement in SRT and SRM. These results are valuable in setting expectations for and counselling families of children considering sequential CIs.

Evidence for opponent process analysis of sound source location in humans

Research with barn owls suggested that sound source location is represented topographically in the brain by an array of neurons each tuned to a narrow range of locations. However, research with small-headed mammals has offered an alternative view in which location is represented by the balance of activity in two opponent channels broadly tuned to the left and right auditory space. Both channels may be present in each auditory cortex, although the channel representing contralateral space may be dominant. Recent studies have suggested that opponent channel coding of space may also apply in humans, although these studies have used a restricted set of spatial cues or probed a restricted set of spatial locations, and there have been contradictory reports as to the relative dominance of the ipsilateral and contralateral channels in each cortex. The current study used electroencephalography (EEG) in conjunction with sound field stimulus presentation to address these issues and to inform the development of an explicit computational model of human sound source localization. Neural responses were compatible with the opponent channel account of sound source localization and with contralateral channel dominance in the left, but not the right, auditory cortex. A computational opponent channel model reproduced every important aspect of the EEG data and allowed inferences about the width of tuning in the spatial channels. Moreover, the model predicted the oft-reported decrease in spatial acuity measured psychophysically with increasing reference azimuth. Predictions of spatial acuity closely matched those measured psychophysically by previous authors.