Everyday listening questionnaire: correlation between subjective hearing and objective performance.

OBJECTIVES: Clinical experience has demonstrated that speech understanding by cochlear implant (CI) recipients has improved over recent years with the development of new technology. The Everyday Listening Questionnaire 2 (ELQ 2) was designed to collect information regarding the challenges faced by CI recipients in everyday listening. The aim of this study was to compare self-assessment of CI users using ELQ 2 with objective speech recognition measures and to compare results between users of older and newer coding strategies. METHODS: During their regular clinical review appointments a group of representative adult CI recipients implanted with the Advanced Bionics implant system were asked to complete the questionnaire. The first 100 patients who agreed to participate in this survey were recruited independent of processor generation and speech coding strategy. Correlations between subjectively scored hearing performance in everyday listening situations and objectively measured speech perception abilities were examined relative to the speech coding strategies used. RESULTS: When subjects were grouped by strategy there were significant differences between users of older 'standard' strategies and users of the newer, currently available strategies (HiRes and HiRes 120), especially in the categories of telephone use and music perception. Significant correlations were found between certain subjective ratings and the objective speech perception data in noise. CONCLUSIONS: There is a good correlation between subjective and objective data. Users of more recent speech coding strategies tend to have fewer problems in difficult hearing situations.

Results of a pilot study with a signal enhancement algorithm for HiRes 120 cochlear implant users.

OBJECTIVE: Cochlear implant users still experience severe limitations regarding sound quality, music appreciation, and speech perception in adverse listening situation. To improve hearing in noisy environments, the incorporation of signal enhancement algorithms was initiated. METHOD: The study group consisted of 13 postlingually deafened adults using HiRes 120. Participants were fitted with 2 versions of the noise reduction algorithm: a moderate and a strong setting. In an immediate session, the HSM sentence test in speech-shaped noise was administered using the clinical program as well as both noise reduction programs. Participants were asked to try all 3 programs in everyday listening situations at home and provide a rating of sound quality and speech perception via a questionnaire (Abbreviated Profile of Hearing Aid Benefit). RESULTS: During the fitting, no difficulties were encountered, and all participants accepted the noise reduction programs without any acclimatization. All participants achieved better results with both noise reduction programs in the HSM sentence test in noise compared with the clinical program. Group mean speech perception scores were highly significantly better for the ClearVoice settings compared with the clinical program score. The majority preferred one of the ClearVoice conditions, with 4 participants for the strong and 3 for the moderate setting. CONCLUSION: Our results demonstrate a real potential benefit for noise reduction algorithms in cochlear implant processors. Although algorithm parameters were not optimized individually, a significant improvement could still be achieved. Further investigation is required to develop fitting guidelines and achieve parameter optimization.

Cochlear implantation in unilateral deaf subjects associated with ipsilateral tinnitus.

OBJECTIVE: In subjects who are deaf and who also have tinnitus in the affected ear, tinnitus treatments based on acoustic input are impossible. On the other hand, tinnitus suppression using electric stimulation has been reported to be successful. Therefore, a study was initiated to investigate the potential of cochlear implantation (CI) in unilateral deaf subjects regarding tinnitus suppression, device acceptance, and restoration of spatial hearing. METHOD: Five subjects with severe to profound unilateral deafness having also ipsilateral tinnitus were enrolled. In monthly visits, the speech processor program was optimized, and the hearing performance as well as tinnitus were monitored. In addition, it was investigated whether the CI improves hearing in adverse listening situations when combined with the normal hearing side. RESULTS: In 3 participants, the tinnitus was significantly suppressed while wearing the device. In the other 2 participants, the tinnitus could be reduced in certain situations. Speech perception tests revealed a significant benefit with the CI in combination with the normal-hearing side for 3 participants. All participants accepted the device in a clinical setting; adaptation of the frequency allocation was not required. CONCLUSION: Improvements were found regarding the hearing and the tinnitus. Not all participants benefit from the CI to the same degree and in the same situations.The results indicate that cochlear implantation in subjects with unilateral severe to profound hearing loss and ipsilateral tinnitus may be beneficial on a case-to-case basis. Further work needs to be performed to define the appropriate indication criteria.

A high rate n-of-m speech processing strategy for the first generation Clarion cochlear implant.

An n-of-m speech coding strategy has been developed for the Clarion Cochlear Implant Series 1.x (1.0 & 1.2). The basic principle is to reduce the number of stimuli per cycle, by neglecting the less significant spectral components, and to concentrate on the more dominant frequency bands. In this study 20 subjects, implanted with a Clarion device, used an n-of-m strategy at 1666 pps per channel. The outcomes using this strategy were compared with the outcomes using conventional processing (CIS at 833 pps/channel). Eight of the 20 subjects underwent additional testing with the n-of-m strategy with the rate set at 833 pps/channel. Using the n-of-m strategy at 1666 pps showed statistically significant improvement in performance over the CIS strategy, with 16 of the 20 subjects achieving better results. However, there was no statistically meaningful difference in performance between n-of-m at 833 pps and the CIS strategy running at the same rate. Results therefore suggest that n-of-m strategy can be an alternative to CIS, particularly when the implant hardware limits the overall stimulation rate.

Investigation of pitch discrimination and the effect of learning for virtual channels realized by current steering.

CONCLUSION: As virtual channels could be perceived by the majority of implant users, they promise potential for advanced speech coding strategies, providing enhanced spectral resolution. An improvement in resolution was found from first stimulation up to 6 months afterwards. OBJECTIVE: Independent current sources allow distribution of the current between adjacent electrode contacts in a defined ratio, thus steering the current. The goal of our study was to investigate a) whether all users were able to distinguish between adjacent physical channels, b) how many users could perceive a distinct pitch as the current was steered between two adjacent contacts and c) whether a learning effect was observed. SUBJECTS AND METHODS: A pitch ranking measurement was performed during an acute test session for a group of 39 cochlear implant users. The results were analysed with respect to the implanted electrode system. The learning process during the first 6 months after implantation was investigated for a selected subgroup. RESULTS: About half of the study participants were able to perceive intermediate channels; 5% were able to discriminate more than eight intermediate channels, which correspond to half of the physical channels. A wide variation was found across the array.

Evaluation of the Harmony soundprocessor in combination with the speech coding strategy HiRes 120.

OBJECTIVE: The Advanced Bionics Harmony BTE processor was developed to support the new speech coding strategy HiRes 120 with a resolution of 120 channels based on "current steering." Compared with the previous Auria, the front end has been re-designed and power consumption reduced. STUDY DESIGN: HiRes 120 as well as the impact of the improved Harmony processing concerning a better speech understanding were evaluated. Subject's performance was evaluated using a test battery of the Hochmair-Schulz-Moser (HSM) sentence test and questionnaires regarding general sound quality, music perception, battery life time and processor handling. PATIENTS: In the first study group, 11 postlingually deafened adult subjects participated with a minimum of 9 months experience. The second study group consisted of 14 postlingually deafened adult subjects with a minimum of 2 years experience. INTERVENTIONS: Tested were the 2 speech coding strategies HiRes and HiRes 120 on the Harmony and the clinical system, respectively. MAIN OUTCOME MEASURES: Speech perception tests in quiet, in CCITT noise, as well as with a competing talker, questionnaires regarding sound quality and handling and perceptual channel tests. RESULTS: A total of 84% showed a clear preference for the Harmony processor compared with their previous processor with HiRes. The speech test results showed a 7.7% average increase in the HSM sentence test with 5 dB SNR competing talker. CONCLUSION: The majority of the subjects wanted to change to the new Harmony processor because of a better understanding in everyday life, handling, and improved battery-life time.

Evaluation of Advanced Bionics high resolution mode.

The objective of this paper is to evaluate the advantages of the Advanced Bionic high resolution mode for speech perception, through a retrospective analysis. Forty-five adult subjects were selected who had a minimum experience of three months' standard mode (mean of 10 months) before switching to high resolution mode. Speech perception was tested in standard mode immediately before fitting with high resolution mode, and again after a maximum of six months high resolution mode usage (mean of two months). A significant improvement was found, between 11 and 17%, depending on the test material. The standard mode preference does not give any indication about the improvement when switching to high resolution. Users who are converted within any study achieve a higher performance improvement than those converted in the clinical routine. This analysis proves the significant benefits of high resolution mode for users, and also indicates the need for guidelines for individual optimization of parameter settings in a high resolution mode program.

Comparison of a paired or sequential stimulation paradigm with advanced bionics' high-resolution mode.

OBJECTIVE: Simultaneous stimulation on two channels was investigated with respect to fully sequential stimulation while controlling for the number of channels and the stimulation rate used. STUDY DESIGN: Only subjects having at least 6 months' experience with conventional Clarion speech coding strategies (CIS, PPS, or SAS) were included. A counterbalanced cross-over design was used to compare the paired stimulation paradigm to the sequential stimulation paradigm. SETTING: The investigation was a prospective, within-subject, repeated-measures experiment. PATIENTS: The study group consisted of 13 postlingually deafened adult subjects. INTERVENTIONS: The following programs were evaluated: 1) 16-channel paired stimulation with 5000 pps per channel; 2) 16-channel sequential stimulation with 2500 pps per channel; and 3) 8-channel sequential stimulation with 5000 pps per channel. MAIN OUTCOME MEASURES: Speech perception tests in quiet and noise, Quality Assessment Questionnaire. RESULTS: On average, both sequential stimulation programs showed comparable results, whereas the program with paired stimulation, on average, provided poorer performance. Several subjects showed a remarkable drop in performance when changing from sequential to paired mode. Although a few subjects showed better performance in quiet when using paired stimulation, they still had poorer performance in noise. A weak trend was found linking the difference between program levels in paired or in sequential stimulation paradigm to the difference in performance with these two settings. CONCLUSION: Results indicate that for all subjects in this group sequential stimulation is more appropriate than paired stimulation. Subjective reports, as well as formal speech perception testing, show that the difference between the two paradigms is pronounced, especially when evaluating in the presence of background noise, the test condition more representative of everyday listening.