Multiple-channel non-linear power hearing instruments for children with severe hearing impairment: long-term follow-up

The long-term benefits of multiple-channel non-linear technology for children with severe hearing impairment have yet to be fully investigated over the longer term. Twenty-one children with severe hearing loss participated in a study comparing performance on measures of audibility, speech understanding (in quiet and noise) and listening situations between the children's current analog hearing aids and a test hearing aid with multiple-channel non-linear compression (DigiFocus II Compact Power). Results were obtained from the children at 2 weeks, 8 weeks, 6 months and 12 months following the fitting of a multiple-channel non-linear hearing instrument. Compared with the children's own hearing instruments, the test instruments provided improved audibility, improvement in speech understanding in quiet and noise, and an improvement in listening skills. The gains in speech understanding were greater in noise than in quiet, suggesting that the test hearing instrument provided greatest improvement when listening to speech in noise. While performance increased over time, there was no statistically significant evidence to support continued acclimatization.     

Multi-microphone technology for severe-to-profound hearing loss

In this study the potential benefit of hearing instruments with multi-microphone technology was investigated in laboratory and in field tests for users with severe-to-profound hearing loss. Twenty-one experienced hearing aid users were fitted with high-power multi-microphone hearing instruments (Phonak PowerZoom P4 AZ). The following evaluations were performed: (i) adaptive speech test (SRT for HSM sentence test) in quiet and in noise with their own instrument and the test instrument in the omnidirectional (basic program) and directional mode (party noise profound+zoom algorithm). (ii) Paired comparisons of loudness, sound quality and speech intelligibility for both the omni and zoom program. (iii) Questionnaires on satisfaction and self-assessment of communication in different listening conditions (Oldenburg Inventory). Only 10 subjects achieved 50% correct (SRT) on the sentence test in noise (speech 0 degrees/noise 180 degrees) with both their own instrument and the test instrument in the omnidirectional mode. However, 15 subjects succeeded in the SRT measurement in the directional mode. The average SRT improvement of the directional over the omnidirectional mode was 13.7 dB. Loudness was judged 'medium loud' for both listening programs. Sound quality and intelligibility were rated significantly better for the zoom program. Compared to their own instrument users' satisfaction with the test instrument was significantly higher, especially in noisy listening situations.     

Speech recognition with in-the-ear and behind-the-ear dual-microphone hearing instruments

The primary purpose of this study was to compare the overall listening benefit in diffuse noise provided by dual-microphone technology in an in-the-ear (ITE) hearing instrument to that provided by dual-microphone technology in a behind-the-ear (BTE) hearing instrument. Further, the study was designed to determine whether the use of the dual-microphone + the manufacturer's party response algorithm in the ITE and BTE hearing instruments provided listening benefit in diffuse noise over their respective omnidirectional microphone modes. Twenty-four adults with mild to moderately severe sensorineural hearing loss were evaluated while wearing binaural BTE and ITE hearing instruments. The results indicated that the dual-microphone + party response mode did provide significant benefit in diffuse noise for both the ITE (3.27 dB signal-to-noise ratio [SNR] improvement) and BTE (5.77 dB SNR improvement) hearing instruments relative to their respective conventional omnidirectional microphones. No significant difference in performance was found between the ITE and BTE hearing instruments when each device was in the dual-microphone + party response mode. It is concluded that the use of dual-microphone technology in both ITE and BTE hearing instruments can improve speech recognition in diffuse noise.     

低压缩阈和非线性放大助听器对重度至极重度聋儿的言语接受与表达能力的影响

目的观察低压缩阈多通道数字信号处理助听器对重度和极重度语前聋儿言语接受和表达水平的影响。方法对14名重度和极重度语前聋儿先后进行了大功率线性助听器和WlDEX的Senso p38和C18＋助听器的选配。并在40dB和65dB水平采用言语声进行音节差别辨别测试、西班牙语单音节和双音节识别测试及言语表达测试。结果在小声言语水平和会话水平。使用低压缩阈多通道数字信号处理助听器对音节差别的分辨和识别测试得分更高：儿童言语发音更准确，言语接受能力提高。结论在独立的频率区域的低压缩阈所提供的柱外可听度。有助于言语接受和表达。试验中低压缩阈多通道数字信号处理助听器（Senso p38和C18＋）可促进听损人群言语能力的发展。建议在听损儿童的康复中选用。     

Comparison of benefits provided by different hearing aid technologies

The performance of 40 hearing-impaired adults with the GN ReSound digital BZ5 hearing instrument was compared with performance with linear hearing aids with input compression limiting (AGC-I) or two-channel analog wide dynamic range compression (WDRC) instruments. The BZ5 was evaluated with an omnidirectional microphone, dual-microphone directionality, and a noise reduction circuit in combination with dual-microphone directionality. Participants were experienced hearing aid users who were wearing linear AGC-I or analog WDRC instruments at the time of enrolment. Performance was assessed using the Connected Speech Test (CST) presented at several presentation levels and under various conditions of signal degradation and by the Profile of Hearing Aid Benefit (PHAB). Subjective ratings of speech understanding, listening comfort, and sound quality/naturalness were also obtained using 11-point interval scales. Small performance advantages were observed for WDRC over linear AGC-I, although WDRC did not have to be implemented digitally for these performance advantages to be realized. Substantial performance advantages for the dual microphones over the omnidirectional microphone were observed in the CST results in noise, but participants generally did not perceive these large advantages in everyday listening. The noise reduction circuit provided improved listening comfort but little change in speech understanding.     

The effects of high-frequency amplification on the objective and subjective performance of hearing instrument users with varying degrees of high-frequency hearing loss.

PURPOSE: The purpose of the present study was to determine if amplifying beyond 2 kHz affected the objective and subjective performance of hearing instrument users with varying degrees of mild-to-severe high-frequency sensorineural hearing loss. METHOD: Twenty participants were fitted binaurally with digital completely-in-the-canal devices with 4-channel wide dynamic range compression (Starkey Axent). Each participant used the hearing instruments for two 6-week trial periods. Each hearing instrument was programmed to maximize high-frequency audibility during 1 trial period and minimize high-frequency audibility during the other trial period. Objective evaluations were conducted in quiet using the Connected Speech Test (CST) and in noise using the CST and the Hearing in Noise Test. Subjective performance was evaluated by administering the Abbreviated Profile of Hearing Aid Benefit and a questionnaire. RESULTS: Results indicated that high-frequency amplification significantly improved objective performance in noise and subjective preference in quiet for listeners with varying degrees of mild-to-severe high-frequency hearing loss. Results also suggested that high-frequency amplification may affect subjective preference in noise and overall for listeners with varying degrees of mild-to-severe high-frequency hearing loss when feedback is eliminated. CONCLUSION: Based on these significant benefits, dispensers should be aware that high-frequency amplification should, at least initially, be provided to the affected high-frequency regions when mild-to-severe hearing loss is present.     

Advantages of binaural hearing provided through bimodal stimulation via a cochlear implant and a conventional hearing aid: a 6-month comparative study

CONCLUSIONS: Our study data demonstrate the additional benefit derived from continued use of a contralateral hearing aid (HA) post-cochlear implantation for speech recognition ability in quiet and in noise. Postoperative bimodal stimulation is recommended for all subjects who show some speech recognition ability in the contralateral ear as it may offer binaural listening advantages in various listening situations encountered in everyday life. OBJECTIVES: To assess the benefits derived from bimodal stimulation for experienced HA users implanted with a cochlear implant (CI) (score=20% in disyllabic test). The correlation between pre- and postoperative performance on speech perception measures was examined to determine additional criteria for recommending bimodal stimulation postoperatively. MATERIAL AND METHODS: A within-subject repeated-measures design was used, with each subject acting as their own control. Assessments were carried out preoperatively in aided monaural and best-aided conditions and at 6 months postoperatively in CI-alone, contralateral HA-alone and bimodal listening conditions. Speech recognition using Spanish words and sentences materials was assessed at conversational level and for soft speech in quiet. Speech comprehension in noise was assessed using word materials at a signal:noise ratio of +10, for coincident speech in noise and for spatially separated speech in noise. Twelve adult native Spanish subjects with a severe-to-profound hearing impairment who were experienced with optimally fitted conventional amplification and who displayed suboptimal speech understanding preoperatively were enrolled in the study. Preoperatively, conventional amplification was worn by five subjects binaurally and by seven monaurally. RESULTS: Postoperatively, superior speech recognition ability in quiet and in noise for disyllabic words was achieved using bimodal stimulation in comparison to performance for either monaural aided condition. Mean improvement in speech recognition in the bimodal condition was significant over performance in the CI-alone condition for disyllabic words in quiet at 70 (p=0.006) and 55 dB SPL (p=0.028), for disyllabic words in noise at +10 dB with speech and noise spatially separated with the noise source closest to the contralateral HA (S0NHA) (p=0.0005) and when the noise source was closest to the CI ear (S0NCI) (p=0.002). When testing word recognition in noise with speech and noise sources coincident in space, word scores were superior in the bimodal condition relative to the CI-alone condition but this improvement was not significant (p=0.07). The advantages of bimodal stimulation included significant effects of binaural summation in quiet and significant binaural squelch effects in both the S0NHA and S0NCI test conditions. All subjects showed superior performance in the binaural situation postoperatively relative to the best-aided condition preoperatively for one or more test situations.     

Relationship between consonant recognition and subjective ratings of hearing aids

The relationships between consonant recognition performance and subjective ratings (using continuous discourse and nonsense syllables as stimuli) of speech understanding, listening comfort, quality, noise interference and overall liking were examined in quiet and in noise using hearing-impaired subjects and seven different hearing aids. Correlations among the subjective scales varied depending on test conditions and test stimuli. Scores on the speech understanding and overall liking scales correlated moderately with scores on a consonant-recognition test presented in noise and when syllables were used as the materials for judgments. The overall liking scale (for a hearing aid) correlated with all other subjective scales and consonant recognition performance. However, the relative contribution of each subjective scale to overall liking varied depending on test conditions and test materials.     

Advantages of binaural hearing provided through bimodal stimulation via a cochlear implant and a conventional hearing aid: A 6-month comparative study

Conclusions

Our study data demonstrate the additional benefit derived from continued use of a contralateral hearing aid (HA) post-cochlear implantation for speech recognition ability in quiet and in noise. Postoperative bimodal stimulation is recommended for all subjects who show some speech recognition ability in the contralateral ear as it may offer binaural listening advantages in various listening situations encountered in everyday life.

Objectives

To assess the benefits derived from bimodal stimulation for experienced HA users implanted with a cochlear implant (CI) (score?≥?20% in disyllabic test). The correlation between pre- and postoperative performance on speech perception measures was examined to determine additional criteria for recommending bimodal stimulation postoperatively.

Material and methods

A within-subject repeated-measures design was used, with each subject acting as their own control. Assessments were carried out preoperatively in aided monaural and best-aided conditions and at 6 months postoperatively in CI-alone, contralateral HA-alone and bimodal listening conditions. Speech recognition using Spanish words and sentences materials was assessed at conversational level and for soft speech in quiet. Speech comprehension in noise was assessed using word materials at a signal:noise ratio of +10, for coincident speech in noise and for spatially separated speech in noise. Twelve adult native Spanish subjects with a severe-to-profound hearing impairment who were experienced with optimally fitted conventional amplification and who displayed suboptimal speech understanding preoperatively were enrolled in the study. Preoperatively, conventional amplification was worn by five subjects binaurally and by seven monaurally.

Results

Postoperatively, superior speech recognition ability in quiet and in noise for disyllabic words was achieved using bimodal stimulation in comparison to performance for either monaural aided condition. Mean improvement in speech recognition in the bimodal condition was significant over performance in the CI-alone condition for disyllabic words in quiet at 70 (p=0.006) and 55 dB SPL (p=0.028), for disyllabic words in noise at +10 dB with speech and noise spatially separated with the noise source closest to the contralateral HA (S0NHA) (p=0.0005) and when the noise source was closest to the CI ear (S0NCI) (p=0.002). When testing word recognition in noise with speech and noise sources coincident in space, word scores were superior in the bimodal condition relative to the CI-alone condition but this improvement was not significant (p=0.07). The advantages of bimodal stimulation included significant effects of binaural summation in quiet and significant binaural squelch effects in both the S0NHA and S0NCI test conditions. All subjects showed superior performance in the binaural situation postoperatively relative to the best-aided condition preoperatively for one or more test situations.     

Advantages of a non-linear frequency compression algorithm in noise

A multichannel non-linear frequency compression algorithm was evaluated in comparison to conventional amplification hearing aids using a test of speech understanding in noise (Oldenburger Satztest—OLSA) and subjective questionnaires. The new algorithm compresses frequencies above a pre-calculated cut off frequency and shifts them to a lower frequency range, thereby providing high-frequency audibility. Low-frequencies, below the compression cut off frequency, are amplified normally. This algorithm is called SoundRecover (SR). In this study, 11 experienced hearing aid users with a severe to profound sensorineural hearing loss were tested. Seven subjects showed enhanced levels of understanding in noise (OLSA) using frequency compression. However, 4 out of the 11 subjects could not benefit from the high-frequency gain. Evaluation using questionnaires demonstrated an increased level of satisfaction after 2 months of experimental devices wearing (p = 0.08) and after 4 months of wearing (p = 0.09), respectively, compared to conventional hearing instruments.     

Actual and predicted word-recognition performance of elderly hearing-impaired listeners

Word-recognition scores in quiet and in noise were obtained from both ears of 101 elderly listeners demonstrating sensorineural hearing loss. These performance scores were compared to word-recognition scores predicted using Articulation Index analysis procedures. Negative difference scores (actual performance less predicted performance) would reflect aspects of the hearing impairment and/or the aging process that extend beyond the simple speech audibility constraints imposed by the hearing loss and masking noise. The distributions for both the left and right ears of difference scores in quiet revealed the majority of scores to be grouped near 0. In contrast, both distributions of difference scores in noise were normally distributed around means of approximately -25. These results suggest that the typical elderly hearing-impaired listener should be expected to demonstrate word-recognition performance in quiet similar to that of a normally hearing listener, given the same level of audibility of the speech material. On the other hand, in noise, this typical listener may be expected to demonstrate some word-recognition performance decrement, even after accounting for the audibility constraints of the hearing loss and noise.     

Improvements in speech perception with an experimental nonlinear frequency compression hearing device

The performance of an experimental frequency compression hearing device was evaluated using tests of speech understanding in quiet. The device compressed frequencies above a programmable cut-off, resulting in those parts of the input signal being shifted to lower frequencies. Below the cut-off, signals were amplified without frequency shifting. Subjects were experienced hearing aid users with moderate-to-severe sensorineural hearing loss and sloping audiograms. Their recognition of monosyllabic words was tested using the experimental device in comparison with conventional hearing aids. Of the 17 subjects, eight showed a significant score improvement (p?<?0.05), whereas one subject showed a significant score decrease. Some of the improvements may have resulted from the better audibility provided in the high frequencies by the experimental device in comparison with the conventional aids. However, a subsequent study found that increasing the high-frequency gain in the conventional aids did not produce equivalent perceptual benefits.     

Improvements in speech perception with an experimental nonlinear frequency compression hearing device

The performance of an experimental frequency compression hearing device was evaluated using tests of speech understanding in quiet. The device compressed frequencies above a programmable cut-off, resulting in those parts of the input signal being shifted to lower frequencies. Below the cut-off, signals were amplified without frequency shifting. Subjects were experienced hearing aid users with moderate-to-severe sensorineural hearing loss and sloping audiograms. Their recognition of monosyllabic words was tested using the experimental device in comparison with conventional hearing aids. Of the 17 subjects, eight showed a significant score improvement (p < 0.05), whereas one subject showed a significant score decrease. Some of the improvements may have resulted from the better audibility provided in the high frequencies by the experimental device in comparison with the conventional aids. However, a subsequent study found that increasing the high-frequency gain in the conventional aids did not produce equivalent perceptual benefits.     

Effect of preferred volume setting on speech audibility in different hearing aid circuits

This study compared preferred volume setting for linear peak clipping, compression limiting, and wide dynamic range compression (WDRC) amplification and quantified speech audibility at the preferred volume setting for each amplification type. Ten listeners with mild-to-moderate hearing loss were fitted monaurally with a behind-the-ear hearing aid programmed sequentially with WDRC, compression limiting, and linear peak clipping amplification. Speech was presented in quiet and in noise at a range of input levels. In each condition, the listener adjusted the volume for maximum clarity. Signal levels were measured using a probe microphone system. There was no significant difference in speech audibility between amplification strategies for any speech level regardless of the presence or absence of background noise. These results imply that the improved audibility advantage of WDRC over linear amplification demonstrated in controlled environments may not be maintained in situations where the hearing aid wearer controls the volume.     

Vibrant Sound Bridge System. A new kind hearing prosthesis for patients with sensorineural hearing loss. 2. Audiological results

OBJECTIVE: Implantable hearing aids present a new treatment modality for patients suffering from sensorineural hearing loss. The functional gain obtained with the partially implantable Symphonix soundbridge system was evaluated in a clinical study. The audiological results achieved with n = 34 patients over a period of up to three years are presented in this second part of the publication. PATIENTS AND METHODS: 34 patients have received the Symphonix Vibrant soundbridge system since February 1997. The average age at implantation was 47.2 years (minimum: 18.9 years; maximum: 80.3 years). All patients have had several years of experience with hearing aids, which, however, provided insufficient functional gain or could not be fitted with a conventional hearing aid for medical reasons (such as auditory ear canal problems). All patients fulfilled the audiological selection criteria as they had bilateral moderate to severe sensorineural hearing loss. As a rule, the ear with poorer performance was implanted. All patients were fitted with the audio processor eight weeks after the implantation. The pure tone thresholds, the functional gain, the monosyllable and sentence understanding (G?ttinger Sentence Test in quiet and noise) were preoperatively and postoperatively assessed. Standardized self-assessment questionnaires were used to evaluate the subjective benefit (PHAB) and the quality of hearing (HDSS) as compared to the preoperative situation. Further hearing tests were performed after four weeks, three, six, nine, twelve, eighteen, twenty-four and thirty-six months postoperatively. During the observation period of up to three years the audioprocessor was updated several times, most recently with the fully digital three-channel-system Vibrant D. The results obtained were documented. RESULTS: Postoperatively, the pure tone threshold with the soundbridge system switched off did not change significantly in the implanted ear. All patients had a functional gain that was either comparable to the gain achieved with hearing aids or better. In particular speech-related frequencies showed improved amplification. The free field speech recognition tests revealed higher scores in quiet and in noise. The patients commended the natural sound quality, the lack of feedback, the absence of occlusion and distortion, the improved speech understanding in noise and the favourable cosmetic appeal. Only two patients failed to achieve better results as compared to their performance with conventional hearing aids. No complications, such as a deterioration of hearing due to inner ear damage or a conductive hearing loss, were observed in the long-term. CONCLUSIONS: The Symphonix Vibrant Soundbridge is a new and promising treatment modality for patients suffering from moderate to severe sensorineural hearing loss. Further improvement of the good results can be expected with improved coupling of the transducer to the ossicular chain and further development of signal processing.     

H?rger?teindikation und -��berpr��fung nach modernen Verfahren der Sprachaudiometrie im Deutschen

The current guidelines for hearing aid supply in Germany employ the often criticised Freiburg monosyllabic speech test (FBE) in quiet. This test can be replaced with the monosyllabic rhyme test by von Wallenberg and Kollmeier (WaKo) in quiet and by the measurement of a speech reception threshold in an interfering noise at a moderate level (45?dB?SPL) using either the G?ttingen or the Oldenburg sentence test (criterion: 2?dB improvement in SNR, ??signal-to-noise ratio??). This procedure was investigated in a group of 38 participants with a sensorineural hearing impairment (mild, moderate or severe hearing loss) and 11 volunteers with normal hearing. On average, comparable indications were achieved. Participants with a mild hearing loss and a selective problem with listening in interfering noise were assessed more fairly.