The Effectiveness of Microcurrent Stimulation Combined with Sound Therapy for Tinnitus Relief: A Preliminary Study.

Various stimulation-based rehabilitation approaches have been proposed to alleviate tinnitus. This study aimed to determine the efficacy of a rehabilitation approach that simultaneously provides microcurrent and sound stimulation for tinnitus relief. Twenty-eight participants with chronic sensorineural tinnitus were randomly assigned to one of two groups based on the rehabilitation approaches (sound therapy-only group and combined microcurrent and sound therapy group). Each participant underwent sound therapy or simultaneous stimulation for approximately 2 h daily for 3 months. The effectiveness of the rehabilitation approaches was determined based on changes in the Korean version of the tinnitus primary function questionnaire (K-TPFQ) and visual analog scale for loudness (VAS-L) scores at baseline, 1.5 months, and 3 months. For the K-TPFQ scores, both groups exhibited a large effect of rehabilitation; however, for the VAS-L scores, the simultaneous stimulation group demonstrated a large effect of rehabilitation, whereas the sound therapy group exhibited a small effect. Therefore, a rehabilitation approach that combines sound stimulation with microcurrent stimulation can improve response and perception in tinnitus.

Trends in Distributions of Hearing Threshold Levels by Ages: A Comparison of the ISO 7029 and Newly Available Country-Specific Data.

Hearing thresholds provide essential information and references about the human auditory system. This study aimed to identify changing trends in distributions of hearing threshold levels across ages by comparing the International Organization for Standardization (ISO) 7029 and newly available data after publishing ISO 7029. To compare ISO 7029 and newly available hearing threshold data after publishing ISO 7029, four country-specific datasets that presented average hearing threshold levels under conditions similar to ISO 7029 were utilized. For frequencies between 125 Hz and 8,000 Hz, the deviations of hearing threshold values by ages from the hearing threshold of the youngest age group for each data point were utilized. For frequencies from 9,000 Hz to 12,500 Hz, the median threshold information was utilized. Hearing threshold data reported after publishing ISO 7029 from the four countries were mostly similar to the ISO 7029 data but tended to deviate in some age groups and sexes. As national hearing threshold trends change, the following ISO 7029 revision suggests the need to integrate hearing threshold data from different countries.

Improving Accuracy and Reliability of Hearing Tests: An Exploration of International Standards.

This study explores the internal standards for hearing tests and benefits of implementing international standard protocols, including the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), and discusses how ISO and IEC standards provide a framework for designing, calibrating, assessing hearing test instruments and methods, and exchanging and comparing data globally. ISO and IEC standards for hearing tests improve accuracy, reliability, and consistency of test results by applying standardized methods and environments. Moreover, they promote international harmonization and data interoperability, enabling information exchange and research collaboration. Those standards for hearing tests are beneficial but have challenges and limitations, such as variation in equipment and calibration, lag in updating standards, variation in implementation and compliance, and lack of coverage of clinical aspects, cultural diversity, and linguistic diversity. These affect the quality and interpretation of test results. Adapting ISO or IEC standards locally would improve their applicability and acceptability, while balancing customization and compatibility with global standards.

Measuring tinnitus in pharmaceutical clinical trials.

This paper reviews methods and considerations for measuring tinnitus in clinical trials designed to evaluate treatment options using investigational medicinal products. Tests applied in tinnitus-related research and clinical practice have their own measurement purposes, advantages, and limitations. If the characteristics of each test method are well understood, the test can be effectively used in clinical trials. For the accuracy of clinical trial results, it is necessary to use a test tool with verified validity, reliability, and sensitivity. If a test tool that is likely to have high variability in the same individual is required in the clinical trial, strategies to increase the reliability of the test, such as repeat measurements, may also be needed. In addition, a test tool that meets the purpose of the clinical trial should be selected. For example, the tinnitus questionnaire is appropriate to assess reactions to tinnitus, and measurements of tinnitus loudness or pitch are appropriate to evaluate the psychoacoustic characteristics of tinnitus. In conclusion, the use of validated test tools that meet the purpose of the trial will help with the accuracy of the clinical trial results.

Methods, Applications, and Limitations of Somatic Maneuvers for the Modulation of Tinnitus.

The modulation of tinnitus through somatic maneuvers is a well-documented phenomenon in tinnitus patients with somatic disorders. The purpose of this study was to review the methods, applications, and limitations of somatic maneuvers. First, 35 somatic maneuvers proposed by various research groups were summarized according to four body areas (jaw, head and neck, eye, and limbs), following which their applications and limitations were assessed. Although some studies have shown that somatic maneuvers can aid in screening for somatic tinnitus and may help alleviate symptoms with repeated practice, the limited number of studies and inconsistent results among studies make it difficult to draw definitive conclusions. Therefore, follow-up studies are required to overcome these limitations and determine whether the treatment of somatic disorders can also aid in alleviating somatic tinnitus.

The Impact of Daily Hours of Sound Therapy on Tinnitus Relief for People With Chronic Tinnitus: A Randomized Controlled Study.

PURPOSE: Tinnitus is defined as the perception of sounds in the absence of extrinsic sound stimuli. Sound therapy is an option for tinnitus rehabilitation, which aims to mitigate the functional and emotional effects of tinnitus. Several studies have reported that a longer duration of sound therapy may result in a greater tinnitus relief effect. However, the relationship between the daily hours of sound therapy and the tinnitus relief effect remains unclear. Thus, we aimed to evaluate the tinnitus relief effect according to the time spent in daily performing sound therapy. METHOD: Fifty-eight chronic tinnitus participants were randomly assigned to three groups according to their daily hours of sound therapy (1-hr, 3-hr, and 5-hr groups), and mixing point-based sound therapy, which adjusts the volume of the external stimulus to blend with the participant's tinnitus sound, was administered for 3 months. The effectiveness of sound therapy was determined based on changes in the tinnitus loudness level, visual analog scale for loudness score, and the Korean version of the Tinnitus Primary Function Questionnaire (K-TPFQ) score between the baseline and 3-month time points. RESULTS: Longer daily sound therapy hours were associated to a greater effect of sound therapy in the tinnitus loudness level and the total K-TPFQ scores, including the emotion and hearing subcategories. Particularly, the 3-hr and 5-hr groups showed a greater tinnitus relief than the 1-hr group. CONCLUSION: An increase in the daily sound therapy hours may increase the possibility of improving tinnitus relief effects.

Notched and Nonnotched Stimuli Are Equally Effective at the Mixing-Point Level in Sound Therapy for Tinnitus Relief.

BACKGROUND: Broadband noise (nonnotched) and notched noise are common sound sources in sound therapy for tinnitus relief. Studies on sound therapy using nonnotched or notched stimuli have reported large and small tinnitus improvements depending on the participant. However, the more effective sound source remains unclear given the among-study methodology differences. PURPOSE: This study aimed to evaluate the tinnitus relief effects of sound therapy using stimuli with different spectral characteristics. RESEARCH DESIGN: This was a prospective study involving within-subject (baseline vs. 12-month follow-up) measurements for two groups (notched noise group vs. broadband noise group). STUDY SAMPLE: We enrolled 30 adults with subjective and tonal tinnitus (notched noise group: 16, broadband noise group: 14). INTERVENTION: The participants underwent 3-hour daily sound therapy using either notched noise or broadband noise for 12 months. The stimulus level for sound therapy was set to each participant's mixing point. DATA COLLECTION AND ANALYSIS: Tinnitus loudness and the Korean version of the Tinnitus Primary Function Questionnaire score were measured at baseline and at the 12-month follow-up time point. RESULTS: Both groups showed a significant improvement in tinnitus loudness and the Korean version of the Tinnitus Primary Function Questionnaire score. CONCLUSION: Notched and nonnotched stimuli are equally effective at the mixing point in sound therapy for tinnitus relief. Individuals with difficulties in tinnitus frequency measurement could easily undergo sound therapy using nonnotched stimuli.

Effects of Tinnitus Sound Therapy Determined Using Subjective Measurements.

BACKGROUND: Sound therapy is generally considered as an effective method for relieving tinnitus. There have been various reports on the effects of tinnitus interventions involving sound therapy as a component; however, there have been only a small number of reports on the effects of sound therapy itself on tinnitus. PURPOSE: The aim of the study is to elucidate whether sound therapy significantly improves tinnitus as determined by subjective measurements. RESEARCH DESIGN: Prospective study involves within-subject (baseline, 3-month, 6-month) measurements. STUDY SAMPLE: This includes 16 adults with subjective and sensorineural tinnitus. INTERVENTION: Participants undertook sound therapy for 3 hours a day for 6 months. The level of stimulus for sound therapy was set to the mixing point of each participant. No counseling was provided. DATA COLLECTION AND ANALYSIS: Participants rated the visual analog scale for loudness and annoyance using a numeric 0 to 100 point scale and completed the Korean version of the Tinnitus Primary Function Questionnaire at the baseline, 3-month, and 6-month time points. RESULTS: Sound therapy led to significant improvements of tinnitus in participants in all subjective measurements. Significant effects were found not only between the baseline and 3-month but also between the 3-month and 6-month follow-ups. CONCLUSION: Results of the present study showed that the sound therapy alone led to significant improvements of tinnitus in participants as assessed by subjective measurements. To improve the effects of sound therapy, consistent sound therapy may be required for a certain period of time such as 3 hours a day over a 6-month period.

Korean Clear Speech Improves Speech Intelligibility for Individuals with Normal Hearing and Individuals with Hearing Loss.

BACKGROUND: Clear speech is an effective communication strategy to improve speech intelligibility. While clear speech in several languages has been shown to significantly benefit intelligibility among listeners with differential hearing sensitivities and across environments of different noise levels, whether these results apply to Korean clear speech is unclear on account of the language's unique acoustic and linguistic characteristics. PURPOSE: This study aimed to measure the intelligibility benefits of Korean clear speech relative to those of conversational speech among listeners with normal hearing and hearing loss. RESEARCH DESIGN: We used a mixed-model design that included both within-subject (effects of speaking style and listening condition) and between-subject (hearing status) elements. DATA COLLECTION AND ANALYSIS: We compared the rationalized arcsine unit scores, which were transformed from the number of keywords recognized and repeated, between clear and conversational speech in groups with different hearing sensitivities across five listening conditions (quiet and 10, 5, 0, and -5 dB signal-to-noise ratio) using a mixed model analysis. RESULTS: The intelligibility scores of Korean clear speech were significantly higher than those of conversational speech under most listening conditions in all groups; the former yielded increases of 6 to 32 rationalized arcsine units in intelligibility. CONCLUSION: The present study provides information on the actual benefits of Korean clear speech for listeners with varying hearing sensitivities. Audiologists or hearing professionals may use this information to establish communication strategies for Korean patients with hearing loss.

Comparison of Speech Rate and Long-Term Average Speech Spectrum between Korean Clear Speech and Conversational Speech.

BACKGROUND AND OBJECTIVES: Clear speech is an effective communication strategy used in difficult listening situations that draws on techniques such as accurate articulation, a slow speech rate, and the inclusion of pauses. Although too slow speech and improperly amplified spectral information can deteriorate overall speech intelligibility, certain amplitude of increments of the mid-frequency bands (1 to 3 dB) and around 50% slower speech rates of clear speech, when compared to those in conversational speech, were reported as factors that can improve speech intelligibility positively. The purpose of this study was to identify whether amplitude increments of mid-frequency areas and slower speech rates were evident in Korean clear speech as they were in English clear speech. SUBJECTS AND METHODS: To compare the acoustic characteristics of the two methods of speech production, the voices of 60 participants were recorded during conversational speech and then again during clear speech using a standardized sentence material. RESULTS: The speech rate and longterm average speech spectrum (LTASS) were analyzed and compared. Speech rates for clear speech were slower than those for conversational speech. Increased amplitudes in the mid-frequency bands were evident for the LTASS of clear speech. CONCLUSIONS: The observed differences in the acoustic characteristics between the two types of speech production suggest that Korean clear speech can be an effective communication strategy to improve speech intelligibility.

Reliability and Validity of a Korean Version of the Tinnitus Primary Function Questionnaire.

Purpose The aim of this study was to evaluate the reliability and validity of a Korean version of the Tinnitus Primary Function Questionnaire (K-TPFQ). Method A total of 79 subjects participated in the study. All participants completed the K-TPFQ, and the Korean versions of the Pittsburgh Sleep Quality Index ( Buysse, Reynolds, Monk, Berman, & Kupfer, 1989 ; Sohn, Kim, Lee, & Cho, 2012 ), the Beck Depression Inventory ( Beck, Ward, Mendelson, Mock, & Erbaugh, 1961 ; Jo, Park, Jo, Ryu, & Han, 2007 ), the State-Trait Anxiety Inventory questionnaire ( Cho & Choi, 1989 ; Spielberger & Gorsuch, 1983 ), and the Tinnitus Handicap Questionnaire ( Kuk, Tyler, Russell, & Jordan, 1990 ). Results The K-TPFQ exhibited good or high internal consistency and reliability (Cronbach's alpha range: .91-.95, item-total correlation range: .50-.82). The total score derived from the items of the K-TPFQ and its subcategories was moderately correlated with that of questionnaires that measure similar parameters (Pearson correlation coefficient range: .50-.79). Conclusions Overall, the results of this study indicate that the K-TPFQ is reliable and valid. Therefore, the current translated version of the K-TPFQ is applicable to subjects with Korean as their 1st language and proves to be a useful tinnitus questionnaire.

Author's Rebuttal to Smits et al. (2018), "Comment on 'Sensitivity of the Speech Intelligibility Index to the Assumed Dynamic Range' by Jin et al. (2017)".

Purpose: The purpose of this letter is to refute the comments written by Smits, Goverts, and Versfeld (2018). Method: Refutations to each issue including the fixed mathematical relationship between dynamic range (DR) and a fitting constant (Q value), deviating results for small DRs, and determination of Speech Intelligibility Index (SII) model parameters are described. Results: Although Smits et al. (2018) correctly identified several issues, those comments do not diminish the results of the original article (Jin, Kates, & Arehart, 2017) in providing new insights for the SII. Conclusions: Jin et al. (2017) clearly provided the impact of languages and DR on the SII, which was the main result of the study.

Sensitivity of the Speech Intelligibility Index to the Assumed Dynamic Range.

Purpose: This study aims to evaluate the sensitivity of the speech intelligibility index (SII) to the assumed speech dynamic range (DR) in different languages and with different types of stimuli. Method: Intelligibility prediction uses the absolute transfer function (ATF) to map the SII value to the predicted intelligibility for a given stimuli. To evaluate the sensitivity of the predicted intelligibility to the assumed DR, ATF-transformed SII scores for English (words), Korean (sentences), and Mandarin (sentences) were derived for DRs ranging from 10 dB to 60 dB. Results: Increasing the assumed DR caused steeper ATFs for all languages. However, high correlation coefficients between predicted and measured intelligibility scores were observed for DRs from 20 dB to 60 dB for ATFs in English, Korean, and Mandarin. Conclusions: Results of the present study indicate that the intelligibility computed from the SII is not sensitive to the assumed DR. The 30-dB DR commonly used in computing the SII is thus a reasonable assumption that produces accurate predictions for different languages and different types of stimuli.

Substitution Patterns of Phoneme Errors in Hearing Aid and Cochlear Implant Users.

BACKGROUND AND OBJECTIVES: It is acknowledged that speech perceptual errors are increased in listeners who have sensorineural hearing loss as noise increases. However, there is a lack of detailed information for their error pattern. The purpose of the present study was to analyze substitution patterns of phoneme errors in Korean hearing aid (HA) and cochlear implant (CI) users who are postlingually deafened adults. SUBJECTS AND METHODS: In quiet and under two noise conditions, the phoneme errors of twenty HA and fourteen CI users were measured by using monosyllabic words, and a substitution pattern was analyzed in terms of manner of articulation. RESULTS: The results showed that both groups had a high percentage of nasal and plosive substitutions regardless of background conditions. CONCLUSIONS: This finding will provide vital information for understanding the speech perception of hearing-impaired listeners and for improving their ability to communicate when applied to auditory training.

Does Language Matter When Using a Graphical Method for Calculating the Speech Intelligibility Index?

BACKGROUND: Graphical methods for calculating the speech intelligibility index (SII), such as the count-the-dot audiogram, are useful tools in quantifying how much weighted audibility is restored when amplification is used for individuals with hearing loss. The band-importance function (BIF), which is an important component of the SII, depends on the language. Thus, language may affect the prediction of weighted audibility using the graphical SII. PURPOSE: The purpose of this study was to apply language-specific BIFs to develop and compare graphical SIIs for English, Korean, and Mandarin. RESEARCH DESIGN: The graphical SIIs were developed and compared using a research design that applied and analyzed existing datasets. DATA COLLECTION AND ANALYSIS: Language-specific BIFs and dynamic ranges were used to derive graphical SIIs for English, Korean, and Mandarin. SII predictions were compared by calculating the language-specific predictions for the same audiometric configurations. RESULTS: The graphical SIIs for English, Korean, and Mandarin yielded different unaided and aided predictions for the same audiogram configurations. CONCLUSIONS: A graphical SII helps patients easily understand their weighted audibility for unaided and aided conditions; thus, it is a useful counseling tool in the clinic. The most accurate graphical SII's will, however, be based on a patient's spoken language.

The Band-Importance Function for the Korean Standard Sentence Lists for Adults.

BACKGROUND AND OBJECTIVES: The band-importance function (BIF) refers to a value characterizing the relative importance of different frequencies to speech intelligibility. The purpose of this study was to derive the BIF for the Korean standard sentence lists for adults (KS-SL-A). SUBJECTS AND METHODS: In this study, sentences from the KS-SL-A were used as the speech material. Twenty-six normal-hearing Korean listeners participated and intelligibility scores in 8 filters with 3 signal-to-noise ratio conditions were obtained. Based on the intelligibility score percentages, the BIF for the KS-SL-A was derived by using an established protocol. RESULTS: Band-importance weights varied across frequency bands. The most important frequency region was around 316 Hz (20.0%), and the importance of the frequency bands below the center frequency (CF) of 1,778 Hz was 59.6%. Therefore, low frequencies below the CF of 1,778 Hz were more important than high frequencies above the CF of 1,778 Hz. CONCLUSIONS: The BIF for KS-SL-A could be applied towards developing a hearing aid fitting formulae for Korean listeners.

Derivations of the band-importance function: A cross-procedure comparison.

The purpose of this study was to compare band-importance functions (BIFs) derived by two different procedures. Intelligibility data from native speakers of Korean were used. BIFs were derived using an established procedure reported by Studebaker and Sherbecoe [J. Speech Lang. Hear. Res. 34, 427-438 (1991)] and by a recently published method reported by Kates [J. Acoust. Soc. Am. 134(5), EL459-EL464 (2013)]. The BIFs produced by the two different procedures were similar. These results indicate that the BIF calculation procedure by Kates is accurate for sentences as well as for the monosyllables used in its derivation.

The Dynamic Range for Korean Standard Sentence Material: A Gender Comparison in a Male and a Female Speakers.

BACKGROUND AND OBJECTIVES: The purpose of this study was to identify differences between the dynamic ranges (DRs) of male and female speakers using Korean standard sentence material. Consideration was especially given to effects within the predefined segmentalized frequency-bands. MATERIALS AND METHODS: We used Korean standard sentence lists for adults as stimuli. Each sentence was normalized to a root-mean-square of 65 dB sound pressure level. The sentences were then modified to ensure there were no pauses, and the modified sentences were passed through a filter bank in order to perform the frequency analysis. Finally, the DR was quantified using a histogram that showed the cumulative envelope distribution levels of the speech in each frequency band. RESULTS: In DRs that were averaged across all frequency bands, there were no significant differences between the male and the female speakers. However, when considering effects within the predefined frequency bands, there were significant differences in several frequency bands between the DRs of male speech and those of female speech. CONCLUSIONS: This study shows that the DR of speech for the male speaker differed from the female speaker in nine frequency bands among 21 frequency bands. These observed differences suggest that a standardized DR of male speech in the band-audibility function of the speech intelligibility index may differ from that of female speech derived in the same way. Further studies are required to derive standardized DRs for Korean speakers.

Dynamic range for speech materials in korean, english, and mandarin: a cross-language comparison.

PURPOSE: The purpose of this study was to identify whether differences in dynamic range (DR) are evident across the spoken languages of Korean, English, and Mandarin. METHOD: Recorded sentence-level speech materials were used as stimuli. DR was quantified using different definitions of DR (defined as the range in decibels from the highest to the lowest signal intensities), for several integration times (from 1 to 512 ms) and in different frequency bands (center frequencies [CFs] ranging from 150 to 8600 Hz). RESULTS: Across the 3 languages, DR was affected in similar ways with regard to changes in DR definition and integration time. In contrast, across-language differences in DR were evident when considering frequency-band effects. Specifically, the DR for Korean was smaller than the English DR and the Mandarin DR in low-frequency bands (less than the CF of 455 Hz). Compared with Korean and Mandarin, the DR for English was smallest in mid-frequency bands (between the CF of 455 Hz and 4050 Hz) and was greatest in high-frequency bands (above the CF of 4050 Hz). CONCLUSION: The observed differences in DR across languages suggest that the best-fit DR for Korean and Mandarin may be different than the best fit for English.

The effect of noise envelope modulation on quality judgments of noisy speech.

This study aims to evaluate how speech quality is affected by noise which varies in modulation from 0% (the lowest correlation with the speech envelope) to 100% (the highest correlation with the speech envelope). Using a scaled paired-comparison forced-choice procedure, ten normal-hearing listeners rated overall preference, noisiness, and distortion of speech stimuli with different noise modulation percentages at 0, 10, and 20 dB signal-to-noise ratios. As noise modulation percentage increased, ratings for overall preference increased, ratings for distortion increased, and ratings for noisiness decreased. The noise modulation effects on quality ratings were significant, even at the same signal-to-noise ratio.