Most Comfortable Loudness Level Research Articles

SpeedCAP: An Efficient Method for Estimating Neural Activation Patterns Using Electrically Evoked Compound Action-Potentials in Cochlear Implant Users.

Electrically evoked compound action-potentials (ECAPs) can be recorded using the electrodes in a cochlear implant (CI) and represent the synchronous responses of the electrically stimulated auditory nerve. ECAPs can be obtained using a forward-masking method that measures the neural response to a probe and masker electrode separately and in combination. The panoramic ECAP (PECAP) analyses measured ECAPs obtained using multiple combinations of masker and probe electrodes and uses a nonlinear optimization algorithm to estimate current spread from each electrode and neural health along the cochlea. However, the measurement of ECAPs from multiple combinations of electrodes is too time consuming for use in clinics. Here, we propose and evaluate SpeedCAP, a speedy method for obtaining the PECAP measurements that minimizes recording time by exploiting redundancies between multiple ECAP measures. In the first study, 11 users of Cochlear Ltd. CIs took part. ECAPs were recorded using the forward-masking artifact-cancelation technique at the most comfortable loudness level (MCL) for every combination of masker and probe electrodes for all active electrodes in the users' MAPs, as per the standard PECAP recording paradigm. The same current levels and recording parameters were then used to collect ECAPs in the same users with the SpeedCAP method. The ECAP amplitudes were then compared between the two conditions, as were the corresponding estimates of neural health and current spread calculated using the PECAP method previously described by Garcia et al. The second study measured SpeedCAP intraoperatively in 8 CI patients and with all maskers and probes presented at the same current level to assess feasibility. ECAPs for the subset of conditions where the masker and probe were presented on the same electrode were compared with those obtained using the slower approach leveraged by the standard clinical software. Data collection time was reduced from ≈45 to ≈8 minutes. There were no significant differences between normalized root mean squared error (RMSE) repeatability metrics for post-operative PECAP and SpeedCAP data, nor for the RMSEs calculated between PECAP and SpeedCAP data. The comparison achieved 80% power to detect effect sizes down to 8.2% RMSE. When between-participant differences were removed, both the neural-health (r = 0.73) and current-spread (r = 0.65) estimates were significantly correlated (p < 0.0001, df = 218) between SpeedCAP and PECAP conditions across all electrodes, and showed RMSE errors of 12.7 ± 4.7% and 16.8 ± 8.8%, respectively (with the ± margins representing 95% confidence intervals). Valid ECAPs were obtained in all patients in the second study, demonstrating intraoperative feasibility of SpeedCAP. No significant differences in RMSEs were detectable between post- and intra-operative ECAP measurements, with the comparison achieving 80% power to detect effect sizes down to 13.3% RMSE. The improved efficiency of SpeedCAP provides time savings facilitating multi-electrode ECAP recordings in routine clinical practice. SpeedCAP data collection is sufficiently quick to record intraoperatively, and adds no more than 8.2% error to the ECAP amplitudes. Such measurements could thereafter be submitted to models such as PECAP to provide patient-specific patterns of neural activation to inform programming of clinical MAPs and identify causes of poor performance at the electrode-nerve interface of CI users. The speed and accuracy of these measurements also opens up a wide range of additional research questions to be addressed.

Loudness Perception and Dynamic Range Depending on Interphase Gaps of Biphasic Pulses in Cochlear Implants

The human auditory nerve can be electrically stimulated by cochlear implants (CIs) with pulse trains consisting of biphasic pulses with small interphase gaps (IPGs). In animal experiments, lower electrically evoked compound action potential (ECAP) thresholds in implanted animals were found for increasing IPGs (2.1, 10, 20, 30 μs). ECAP thresholds may correlate with loudness thresholds. Therefore, in this study, the IPG effect on loudness and dynamic range was investigated in nine CI subjects. A loudness-matching procedure was designed with three different IPGs (2.1, 10, 30 μs) at three different pulse rates (200, 600, 1000 pps). An adaptive loudness-balancing test was performed at the 50% stimulus amplitude level of the dynamic range and most comfortable loudness level (MCL). Increasing the IPG or increasing the pulse rate led to a significant decrease in stimulus amplitude for 50% level and MCL in the adaptive test. Because the stimulus amplitudes for 50% level and MCL decreased in a different manner, the calculated upper dynamic range between MCL and 50% level significantly decreased for increasing IPG between 0.24 and 0.38 dB. This decrease in the upper dynamic range was observed for all pulse rates. It is possible to reduce the stimulus amplitude level for the same loudness impression using larger IPGs in CIs; however, larger IPGs decrease the dynamic range. These findings could help during the fitting process of CIs to find the balance between saving battery and a proper dynamic range.

Clinical Experience of Vibroplasty With Direct Coupling to the Oval Window Without Use of a Coupler.

To investigate the efficacy of direct implantation of a Vibrant Soundbridge (VSB) implant in the oval window (OW) without the use of an OW coupler in patients with severe mixed hearing loss. Retrospective chart review METHODS: A total of 62 patients underwent VSB implantation between July 2016 and December 2018 at Severance Hospital in Seoul, South Korea. Among them, eight patients (nine ears) with moderate-to-severe mixed hearing loss were implanted with a VSB directly in the OW. A floating mass transducer (FMT) was attached to the stapes footplate and covered with tragal cartilage. The outcomes were evaluated using pure-tone audiogram and speech audiogram preoperatively and postoperatively. Word recognition score (WRS; % correct) were measured at the most comfortable loudness (MCL) level to evaluate speech perception. All cases posed difficulty with round window vibroplasty during surgery, and eventually, an FMT was appropriately placed in the OW without a coupler. Preoperative and postoperative bone conduction thresholds were not different. VSB-aided threshold improved in terms of functional and effective gains. Interestingly, four cases showed improved air conduction thresholds without the use of a VSB. In addition, MCL level with a VSB was significantly lower than that with a hearing aid, and VSB-aided WRS improved over time. Direct implantation of a VSB in the OW without the use of a coupler showed favorable hearing outcomes, and the OW vibroplasty was safe. Direct OW vibroplasty without a coupler is a reliable procedure and can be a good option for hearing rehabilitation in patients with severe mixed hearing loss. 4 Laryngoscope, 2020.

Using Electrically-evoked Compound Action Potentials to Estimate Perceptive Levels in Experienced Adult Cochlear Implant Users.

The cochlear implant (CI) fitting level prediction accuracy of electrically-evoked compound action potential (ECAP) should be enhanced by the addition of demographic data in models. No accurate automated fitting of CI based on ECAP has yet been proposed. We recorded ECAP in 45 adults who had been using MED-EL CIs for more than 11 months and collected the most comfortable loudness level (MCL) used for CI fitting (prog-MCL), perception thresholds (meas-THR), and MCL (meas-MCL) measured with the stimulation used for ECAP recording. Linear mixed models taking into account cochlear site factors were computed to explain prog-MCL, meas-MCL, and meas-THR. Cochlear region and ECAP threshold were predictors of the three levels. In addition, significant predictors were the ECAP amplitude for the prog-MCL and the duration of deafness for the prog-MCL and the meas-THR. Estimations were more accurate for the meas-THR, then the meas-MCL, and finally the prog-MCL. These results show that 1) ECAP thresholds are more closely related to perception threshold than to comfort level, 2) predictions are more accurate when the inter-subject and cochlear regions variations are considered, and 3) differences between the stimulations used for ECAP recording and for CI fitting make it difficult to accurately predict the prog-MCL from the ECAP recording. Predicted prog-MCL could be used as bases for fitting but should be used with care to avoid any uncomfortable or painful stimulation.

Assessing the efficacy of hearing-aid amplification using a phoneme test.

Consonant-vowel (CV) perception experiments provide valuable insights into how humans process speech. Here, two CV identification experiments were conducted in a group of hearing-impaired (HI) listeners, using 14 consonants followed by the vowel /ɑ/. The CVs were presented in quiet and with added speech-shaped noise at signal-to-noise ratios of 0, 6, and 12 dB. The HI listeners were provided with two different amplification schemes for the CVs. In the first experiment, a frequency-independent amplification (flat-gain) was provided and the CVs were presented at the most-comfortable loudness level. In the second experiment, a frequency-dependent prescriptive gain was provided. The CV identification results showed that, while the average recognition error score obtained with the frequency-dependent amplification was lower than that obtained with the flat-gain, the main confusions made by the listeners on a token basis remained the same in a majority of the cases. An entropy measure and an angular distance measure were proposed to assess the highly individual effects of the frequency-dependent gain on the consonant confusions in the HI listeners. The results suggest that the proposed measures, in combination with a well-controlled phoneme speech test, may be used to assess the impact of hearing-aid signal processing on speech intelligibility.

A Comparison of Presentation Levels to Maximize Word Recognition Scores

While testing suprathreshold word recognition at multiple levels is considered best practice, studies on practice patterns do not suggest that this is common practice. Audiologists often test at a presentation level intended to maximize recognition scores, but methods for selecting this level are not well established for a wide range of hearing losses. To determine the presentation level methods that resulted in maximum suprathreshold phoneme-recognition scores while avoiding loudness discomfort. Performance-intensity functions were obtained for 40 participants with sensorineural hearing loss using the Computer-Assisted Speech Perception Assessment. Participants had either gradually sloping (mild, moderate, moderately severe/severe) or steeply sloping losses. Performance-intensity functions were obtained at presentation levels ranging from 10 dB above the SRT to 5 dB below the UCL (uncomfortable level). In addition, categorical loudness ratings were obtained across a range of intensities using speech stimuli. Scores obtained at UCL - 5 dB (maximum level below loudness discomfort) were compared to four alternative presentation-level methods. The alternative presentation-level methods included sensation level (SL; 2 kHz reference, SRT reference), a fixed-level (95 dB SPL) method, and the most comfortable loudness level (MCL). For the SL methods, scores used in the analysis were selected separately for the SRT and 2 kHz references based on several criteria. The general goal was to choose levels that represented asymptotic performance while avoiding loudness discomfort. The selection of SLs varied across the range of hearing losses. Scores obtained using the different presentation-level methods were compared to scores obtained using UCL - 5 dB. For the mild hearing loss group, the mean phoneme scores were similar for all presentation levels. For the moderately severe/severe group, the highest mean score was obtained using UCL - 5 dB. For the moderate and steeply sloping groups, the mean scores obtained using 2 kHz SL were equivalent to UCL - 5 dB, whereas scores obtained using the SRT SL were significantly lower than those obtained using UCL - 5 dB. The mean scores corresponding to MCL and 95 dB SPL were significantly lower than scores for UCL - 5 dB for the moderate and the moderately severe/severe group. For participants with mild to moderate gradually sloping losses and for those with steeply sloping losses, the UCL - 5 dB and the 2 kHz SL methods resulted in the highest scores without exceeding listeners' UCLs. For participants with moderately severe/severe losses, the UCL - 5 dB method resulted in the highest phoneme recognition scores.

Acceptance of Noise With Intelligible, Reversed, and Unfamiliar Primary Discourse

The purpose of this study was to investigate the effects of intelligible and unintelligible primary discourse on acceptance of noise. Of particular interest was the effect of intelligibility on the most comfortable loudness (MCL) component of acceptable noise level (ANL). ANLs were measured for 30 participants using an intelligible discourse, a reversed discourse, and an unfamiliar primary discourse. For each discourse, MCL and background noise level (BNL) were found. The ANL was then computed by subtracting the mean BNL from the MCL. The intelligibility of the primary discourse did not affect MCL. The ANL was significantly different for the intelligible versus reversed condition and the intelligible versus unfamiliar (Chinese) condition. Results indicate that ANL may change as speech intelligibility changes and/or speech recognition ability decreases in adults with normal hearing.

純音気導しきい値と快適レベル（ＭＣＬ），不快レベル（ＵＣＬ）の関係について

純音気導しきい値と快適レベル（ＭＣＬ），不快レベル（ＵＣＬ）の関係について

DANTALE: a new Danish speech material.

A new Danish speech material (DANTALE) for clinical and experimental speech audiometry is digitally recorded on compact disc (CD). The speech material is designed to meet present audiological requirements at Danish hearing centres. One channel of the CD contains the speech signals and the other a masking noise. The CD also contains various calibration signals recorded on both channels at the end of the CD. The speech material compromises: 1) Digit triplets for the measurement of speech reception threshold (SRT). 2) Lists of monosyllabic words for the measurement of discrimination score (DS) for adults, children and small children. The word lists for the adults are equalized with regard to important phonetic and "visual" elements and the word lists for the children consist of minimal pairs. 3) Continuous speech for the measurement of the most comfortable loudness level (MCL), assessment of hearing aid fitting and the like. The masking noise is an amplitude-modulated, speech-shaped noise signal, which is designed to simulate a 4-person speech babble in order to assess both the frequency selectivity and the temporal resolution. The speech material is described and the long-term power spectra and modulation spectra are given.

Effects of bandwidth and stimulus type on most comfortable loudness levels of hearing-impaired listeners.

Measurements were made of the effects of stimulus bandwidth and type (speech bands versus pure tones) on interfrequency differences at the most comfortable loudness level (MCL). The MCLs were measured for speech bands of three bandwidths (1/3 octave, 1 octave, and 1 2/3 octaves) at three frequencies (0.4 kHz, 1.25 kHz, and 3.15 kHz) for 11 sensorineurally hearing-impaired subjects (14 test ears). The MCLs were also measured with pulsed pure tones. It was found that bandwidth and stimulus type both had significant effects on interfrequency differences in MCLs. Also, the mean speech band MCLs were significantly higher than the mean pure-tone MCLs. A subsidiary experiment suggested that, when bands of speech from different frequency regions are all presented at MCL, they will be approximately, but not precisely, equal in loudness. The findings have implications for hearing aid selection procedures because most aim to amplify all frequency bands of speech to MCL, or equal loudness at a comfortable level. The use of different types or bandwidths of test stimuli would result in substantially different frequency response prescriptions in some cases.

Preferred listening levels for bands of speech in relation to hearing aid selection.

The Most Comfortable Loudness Level (MCL) was measured for 24 normal-hearing subjects, using narrow bands of speech having centre frequencies of 0.25, 0.5, 1.2 and 4kHz. MCL's were equivalent for octave band and one-third octave band stimuli. The sensation levels (SL) for various frequencies closely matched the SL of the 60 phon equal loudness contour for pure tones. It was concluded, for levels around MCL, sounds which are equally comfortable are equally loud and that equal loudness contours for pure tones are also applicable to narrow bands of speech. Some implications for hearing aid selection are discussed. However, this investigation was primarily a preliminary to other studies more directly related to hearing aid selection issues.

騒音性聴力損失者のコムニケーション障害に関する研究

Up to the present social evaluation of the degree of hearing loss is made by the average threshold values for several, pure tones involved in the acoustic range related to speech. This average indicates numerically only a qualitative aspect of the communication capacity. The language used in our daily life is formed by tones of various frequencies and intensities. Accordingly, the degree of actual competence of communication can not simply. be indicated by such average values. Threshold is the sound-level which is just noticeable. Therefore, the scale related to easiness for hearing should be included into the social evaluation on the degree of hearing loss.From the above-mentioned view point, this study was made for clarifying the relationship between the auditory threshold and the most comfortable loudness level (MCL) elicitable by pure-tone and speech audiometry. And more over a classification on 20 monosyllables was made by using the “hard-easy” scale for listening. The subjects were 124 male workers (248 ears) engaged in noisy work-shops. Noise levels in these work-shops were 90 dB (A) or over.The following results were obtained : (1) High positive correlations were found between the threshold at 4000 Hz and those at 3000 and 6000 Hz, and between the threshold at 1000 Hz and those at 500 and 2000 Hz. From these facts, 1000 Hz and 4000 Hz were useful test-frequencies for early detection of noise-induced hearing loss.(2) High positive correlation between the threshold and MCL was found in at each frequency, especially in high frequencies.(3) Inverse correlation was found as significant between the threshold and MCL-threshold. That is, a recruitment phenomenon was observed in workers with noise-induced hearing loss.(4) The auditory threshold at which MCL begins to increase significantly above the normal MCL level was 30 dB at 4000 Hz and 0 dB at the average frequency value (C2+2C3+C4) /4 or (C2+2C3+2C4+C5) /6.The auditory threshold at which the impairment of communication in daily life begins was 50 dB at 4000 Hz, 0 dB at the average value (C2+2C3+C4) /4, and 20 dB at the average value (C2+ 2C3+2C4+C5) /6.(5) Monosyllables listened easily were “A”, “Wa”, “To” and “O”, while those hard of listening were “Ji”, “Ki”, “Ne”, “Su”, “Shi”, “Te” and “Ri”.(6) Monosyllables with which the subjects frequently tended to confused were as follows : “Ha”, “Ta”, “Mo”, “Ba”, “Ga”, “Te” and “Ne”. The confusion was mainly related to the consonant coming at the top of the word.(7) In the examination of articulation of the monosyllables at the minimum intelligible level, “Ni”, “Shi”, “Ga”, “Ki” and “Su” showed higher rates in subjects with normal auditory threshold than in those with hearing loss.(8) In the examination of articulation of the monosyllables at MCL (for sentence), “Ki”, “Su”, “Te” and “Ji” showed higher rate in subjects with normal auditory threshold than in those with hearing loss.(9) In the examination of MCL for monosyllables, those monosyllables which showed the same pattern mentioned above were “Ni”, “Su” and “Ji”, but “Ri” showed significantly lower articulation rate in subjects with hearing loss.

Effects of method of measurement on most comfortable loudness level for speech.

Eighteen college men and 18 college women, all with normal hearing, were tested for the effects of three variables upon most comfortable loudness (MCL) level for speech. These variables were: (1) three measurement methods, (2) sex of listener, and (3) repeated testing. MCL levels for speech were measured in an initial test session and a retest session by the method of adjustment, the method of limits, and the Bekesy audiometer. Results showed that: (1) all three measurement methods produced similar mean MCL levels in both test and retest, (2) mean MCL levels did not change significantly from test to retest for any single measurement method, (3) sex of listener did not significantly affect mean MCL level, (4) MCL levels as measured by the three methods were significantly correlated, (5) test-retest correlations for each measurement method were significant, and (6) Bekesy audiometer tracings of MCL level remained stable over the four and one-half minute test periods in both initial test sessions and in retest sessions.