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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.

Background: The aim of this study is to observe the application of the Chinese version of Tinnitus Handicap Inventory-China in Tinnitus patients and verify its reliability and validity., Methods: About 1129 patients with tinnitus as the first complaint were selected as subjects. The patients were randomly divided into 2 groups: exploration group (n = 565), whose data were analyzed with reliability analysis method using Statistical Package for the Social Sciences software 19.0, validation group (n = 564), whose data were analyzed with validity analysis method using AMOS21.0., Results: (1) Reliability test: The Cronbach's α coefficients of the Tinnitus Handicap Inventory-China scale in both groups were 0.94, among which, the Cronbach's α coefficients of functional factor (F), emotion factor (E), and catastrophic factor (C) in group E were 0.87, 0.90, and 0.78, respectively. The half-reliability of the 2 components is 0.87. The correlation coefficient between items and the scale in group E and group V is 0.36-0.78 and 0.33-0.77, respectively. (2) Content validity: The Kaiser-Meyer-Olkin value of group E is 0.96, a total of 4 common factors were extracted, and the cumulative interpretation rate is 57.844%. The number of factors with load less than 0.4 on the 4 common factors is only 1 (F24), suggesting that this factor had little significance; the number of factors with load more than 0.4 on the 2 common factors is 8 (F1, E6, F9, C11, F15, E21, E22, and C23), suggesting that patients had different understandings of these 8 questions. (3) Structural validity: The root mean square error of approximation value of the AMOS structural model in group V is 0.065, and the root mean square residual value is 0.114, indicating low fitness; the NC value is 3.353, indicating good fitness of the scale, but it still needed to be simplified., Conclusion: The Chinese version of Tinnitus Handicap Inventory-China has a high reliability when applied in China, but the content validity and structure validity are not high, and the clinical practicability needs to be improved.

This is a retrospective longitudinal study that uses data from the National Health Insurance Research Database (NHIRD) of Taiwan of which hypothyroid patients who received a diagnosis between 2000 and 2010 were selected and followed up until 2011. The primary outcome of this study was the occurrence of tinnitus (ICD-9-CM code 388.3). The relevant comorbidities were selected as potential confounders according to the literature, which included vertigo (ICD-9-CM code 386), insomnia (ICD-9-CM code 780), anxiety (ICD-9-CM code 300.00), and hearing loss (ICD-9-CM code 388-389). The overall incidence of tinnitus was significantly higher in the hypothyroidism cohort than in the non-hypothyroidism cohort (9.49 vs. 6.03 per 1000 person-years), with an adjusted HR of 1.35 (95% CI 1.18-1.54) after adjusting potential confounders. The incidences of tinnitus, as stratified by gender, age, comorbidity, and follow-up time, were all significantly higher in the hypothyroidism cohort than those in the non-hypothyroidism cohort. The incidence of tinnitus significantly increased with age (aHR = 1.01, 95% CI 1.01-1.02). In conclusion, we report the relationship between hypothyroidism and the increased risk for tinnitus. We also found that hypothyroidism patients are at increased risk of developing tinnitus when associated with comorbidities including vertigo, hearing loss, and insomnia., (© 2022. The Author(s).)

Background: An association between thyroid disease and tinnitus has been described previously but further longitudinal, population-based studies are limited., Objective: To investigate the incidence of tinnitus in patients with hyperthyroidism in a national sample, and to identify risk level and associated factors for tinnitus in hyperthyroidism patients., Design: Retrospective cohort study. Patient data were collected from the Longitudinal Health Insurance Database (LHID 2000), which includes national claims data of patient expenditures for admissions or ambulatory care from 1996 to 2011., Setting: Taiwan hospitals and clinics providing healthcare nationwide., Participants: Patients aged 20 years and older with newly diagnosed hyperthyroidism (ICD-9-CM code 242) between 2000-2010 were selected as the study cohort. Hyperthyroidism patient cohort were identified from the LHID2000. Those with tinnitus history (ICD-9-CM code 388.3) before the index date (first hyperthyroidism diagnosis), younger than 20 years, and with incomplete demographic data were excluded. The non-hyperthyroidism cohort included patients with no history of hyperthyroidism and no documented tinnitus., Main Outcomes and Measures: Incidence of tinnitus was the primary outcome. Baseline demographic factors and comorbidities possibly associated with tinnitus, including age, sex, and comorbidities of hearing loss, vertigo, insomnia and anxiety, were retrieved from the LHID 2000. Patients were followed until end of 2011., Results: During the study period, 780 (4.9%) hyperthyroidism patients and 2007 (3.2%) non-hyperthyroidism controls developed tinnitus. Incidence rate of tinnitus in the hyperthyroidism cohort was significantly higher in hyperthyroidism cohort (7.86 vs. 5.05 per 1000 person-years) than that in non-hyperthyroidism cohort. A higher proportion of patients with hyperthyroidism had comorbid insomnia (45.1% vs. 30.9%) and anxiety (14.0% vs. 5.73%) than those without hyperthyroidism. After adjusting for age, gender and comorbidities (vertigo, insomnia, anxiety, hearing loss), hyperthyroidism patients had 1.38-fold higher risk of tinnitus (95% CI = 1.27-1.50) than those without hyperthyroidism., Conclusions: This large population-based study suggests patients with diagnosed hyperthyroidism was more prone to develop tinnitus. Our findings suggest evaluation for comorbid vertigo, insomnia, anxiety and/or hearing loss may identify patients who are at high risk of developing tinnitus in patients with hyperthyroidism., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Wang, Chiu, Chen, Chang, Tyler, Rojas-Roncancio, Coelho, Mancini, Lin, Lin and Tsai.)

Purpose: Noise pollution in urban areas is increasing steadily, and the study of road traffic noises and their effects on the auditory system was rare. This study investigated the potential effects of road traffic noise on auditory systems and hearing., Methods: A case-control study recruited outpatients from the Otolaryngology department. The case group ( n  = 41) had binaural hearing loss (HL) of standard pure-tone average(PTA)  ≥ 25 dB or high frequency PTA ≥ 25 dB, while the control group ( n  = 39) had binaural hearing level of any frequency < 25 dB. Detailed otologic evaluations were performed. Between-group data were evaluated using logistic regression analysis. Case or control group was identified based on the audiogram., Results: A total of 80 subjects were recruited, including 41 with hearing impairment and 39 as control. The mean exposure level of road traffic noise was significantly higher in the case group than the control group ( p  = 0.005). A crude OR of 5.78 showed an increased risk of greater than 70 dB of road traffic noise on hearing impairment and tinnitus ( p  < 0.001). The aOR of 9.24 ( p  = 0.002) from a multiple variate analysis suggested that road traffic noise levels greater than 70 dB may have a damaging effect on hearing. Damaging effects on hearing persisted even after adjusting for confounders in the full multivariate model (aOR of 9.24 [95% CI: 2.198-38.869]; p  = 0.002)., Conclusions: Exposing to road traffic noise greater than 70 dB showed an increased risk of damage to the auditory system. These results might help public health administrators and physicians to develop programs that address the health dangers of noise., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© Springer Nature Switzerland AG 2021.)

Objectives: This study aimed to report the auditory performance in children with cochleovestibular malformation (CVM)/cochlear nerve deficiency (CND) who were implanted early at the Universiti Kebangsaan Malaysia Medical Centre, using Categorical Auditory Performance (CAP)-II score and Speech Intelligibility Rating (SIR) scales, and to compare the outcome of their matched counterparts., Materials and Methods: A total of 14 children with CVM/CND with unilateral cochlear implant (CI) implanted before the age of 4 years old were matched and compared with 14 children with normal inner ear structures. Their improvement in auditory performance was evaluated twice using CAP-II score and SIR scales at 6-month intervals, with the baseline evaluation done at least 6 months after implantation., Results: The average age of implantation was 31±8 and 33±7 months for the control group and the case (CVM/CND) group, respectively. Overall, there were no significant differences in outcome when comparing the entire cohort of case subjects and their matched control subjects in this study. However, the improvement in CAP-II scores and SIR scales among the case subjects in between the first and second evaluations was statistically significant (p=0.040 and p=0.034, respectively). With longer duration of CI usage, children with CVM/CND showed significant speech perception outcome evident by their SIR scales (p=0.011)., Conclusion: Children with radiographically malformed inner ear structures who were implanted before the age of 4 years have comparable performance to their matched counterparts, evident by their similar improvement of CAP-II scores and SIR scales over time. Hence, this group of children benefited from cochlear implantation.

Background and Objectives: It is important to understand the frequency region of cues used, and not used, by cochlear implant (CI) recipients. Speech and environmental sound recognition by individuals with CI and normal-hearing (NH) was measured. Gradients were also computed to evaluate the pattern of change in identification performance with respect to the low-pass filtering or high-pass filtering cutoff frequencies., Subjects and Methods: Frequency-limiting effects were implemented in the acoustic waveforms by passing the signals through low-pass filters (LPFs) or high-pass filters (HPFs) with seven different cutoff frequencies. Identification of Korean vowels and consonants produced by a male and female speaker and environmental sounds was measured. Crossover frequencies were determined for each identification test, where the LPF and HPF conditions show the identical identification scores., Results: CI and NH subjects showed changes in identification performance in a similar manner as a function of cutoff frequency for the LPF and HPF conditions, suggesting that the degraded spectral information in the acoustic signals may similarly constraint the identification performance for both subject groups. However, CI subjects were generally less efficient than NH subjects in using the limited spectral information for speech and environmental sound identification due to the inefficient coding of acoustic cues through the CI sound processors., Conclusions: This finding will provide vital information in Korean for understanding how different the frequency information is in receiving speech and environmental sounds by CI processor from normal hearing.

Five bilateral cochlear implant users were tested for their localization abilities and speech understanding in noise, for both monaural and binaural listening conditions. They also participated in lateralization tasks to assess the impact of variations in interaural time delays (ITDs) and interaural level differences (ILDs) for electrical pulse trains under direct computer control. The localization task used pink noise bursts presented from an eight-loudspeaker array spanning an arc of approximately 108 degrees in front of the listeners at ear level (0-degree elevation). Subjects showed large benefits from bilateral device use compared to either side alone. Typical root-mean-square (rms) averaged errors across all eight loudspeakers in the array were about 10 degrees for bilateral device use and ranged from 20 degrees to 60 degrees using either ear alone. Speech reception thresholds (SRTs) were measured for sentences presented from directly in front of the listeners (0 degrees) in spectrally matching speech-weighted noise at either 0 degrees, +90 degrees or -90 degrees for four subjects out of five tested who could perform the task. For noise to either side, bilateral device use showed a substantial benefit over unilateral device use when noise was ipsilateral to the unilateral device. This was primarily because of monaural head-shadow effects, which resulted in robust SRT improvements (P<0.001) of about 4 to 5 dB when ipsilateral and contralateral noise positions were compared. The additional benefit of using both ears compared to the shadowed ear (i.e., binaural unmasking) was only 1 or 2 dB and less robust (P = 0.04). Results from the lateralization studies showed consistently good sensitivity to ILDs; better than the smallest level adjustment available in the implants (0.17 dB) for some subjects. Sensitivity to ITDs was moderate on the other hand, typically of the order of 100 micros. ITD sensitivity deteriorated rapidly when stimulation rates for unmodulated pulse-trains increased above a few hundred Hz but at 800 pps showed sensitivity comparable to 50-pps pulse-trains when a 50-Hz modulation was applied. In our opinion, these results clearly demonstrate important benefits are available from bilateral implantation, both for localizing sounds (in quiet) and for listening in noise when signal and noise sources are spatially separated. The data do indicate, however, that effects of interaural timing cues are weaker than those from interaural level cues and according to our psychophysical findings rely on the availability of low-rate information below a few hundred Hz.

This study examined the average and individual performance over time of 49 adult cochlear implant subjects. Subjects were randomly assigned to receive either the Ineraid cochlear implant, with analog processing, or the Nucleus cochlear implant, with feature-extraction processing. All subjects had postlingual profound bilateral sensorineural hearing loss and received no significant benefit from hearing aids before implantation. Group data were examined in two ways. First, only subjects who had complete data over the test period were examined. Second, an analysis of all available data was carried out by mixed linear-model analysis. In this analysis, to account for missed follow-ups at the planned intervals, data consisting of the observations closest in time to the planned test times were modeled by natural splines with knots at the planned follow-up times. Contrasts between all pairs of planned follow-up times for each device were tested, as were contrasts between devices at each planned follow-up time. Results indicated little difference between the performance of the Ineraid and Nucleus subjects in their level of performance or their rate of learning. Postimplantation performance was typically superior to preimplantation performance within 9 months, and continued to improve up to 18-30 months depending on the speech perception measure. In some subjects, improvements in speech perception measures were observed up to four or five years postimplantation. There was also evidence that three subjects had a decrement in overall speech perception performance, although their postimplantation scores were always higher than their preimplantation scores. In at least one subjects this was likely a result of age-related cognition decrements.

Fifty-four of the better cochlear-implant patients from Europe and the United States were tested on two consonant recognition tests using nonsense syllables. One was produced in an accent appropriate for their own language by a male and a female talker. Recorded tokens of /ibi, idi, igi, ipi, iti, iki, ifi, ivi, ifi, isi, izi, imi, ini/ were presented. With the French syllables, six patients with the Chorimac device averaged 18% correct (6%-29%). With the German syllables, nine patients with the 3M/Vienna device averaged 34% correct (17%-44%), ten patients with the Nucleus device (tested in Hannover) averaged 31% correct (19%-42%), and ten patients with the Duren/Cologne device averaged 27% correct (10%-56%). With the English syllables, ten patients with the Nucleus device (tested in the United States) averaged 42% correct (29%-62%), and nine patients with the Symbion device averaged 46% correct (31%-69%). An information-transmission analysis and sequential information-transfer analysis of the confusions suggested that different implants provided differing amounts of feature information. The place of articulation feature was typically the most difficult to code for all implants. In the second test a male and a female talker recorded the stimuli /ibi, idi, igi, imi, ini, ifi, isi, izi/ in a single manner that was appropriate for all three languages. Six patients with the Chorimac device averaged 27% (13%-48%), ten patients with the Duren/Cologne implant averaged 29% (15%-75%), ten patients with the Nucleus device (tested in Hannover) averaged 40% (25%-58%), ten patients with the Nucleus device (tested in the United States) averaged 49% (40%-60%), nine patients with the Symbion device averaged 61% (40%-75%), and nine patients with the 3M/Vienna device averaged 41% (29%-52%) correct.

Thresholds for 2-kHz sinusoidal signals were determined in the presence of a notched-noise masker, for six normal-hearing listeners and 12 listeners with cochlear hearing losses. Following Patterson and Nimmo Smith [J. Acoust. Soc. Am. 67, 229-245 (1980)], conditions were used where the notch was placed both symmetrically and asymmetrically about the signal frequency. The auditory filter shape for both the low- and high-frequency side of the filter was calculated using the rounded-exponential form of the filter. In six hearing-impaired listeners, the auditory filter shape showed a shallow low-frequency skirt indicating pronounced susceptibility to the upward spread of masking. In two hearing-impaired listeners, the filter shape showed a shallow high-frequency skirt, indicating pronounced susceptibility to the downward spread of masking. Two other listeners with mild threshold losses had steeper and more symmetric filters than normal, suggesting either a small conductive loss or an attenuation factor of sensorineural origin not associated with a degradation of frequency resolution. In the remaining two listeners, the auditory filter had too little selectivity for its shape to be reliably determined.

Several studies using bandlimited masking noise have indicated that NOSO frequency resolution is better than that for NOS pi. The present study examined NOSO and NOS pi frequency resolution with two different masking methods: bandlimited noise and notched noise. Noise spectrum levels of 10, 30, and 50 dB/Hz were used. Thresholds were determined for a 500-Hz signal, using a three-alternative forced-choice adaptive procedure, as a function of masker bandwidth and notchwidth. For NOSO presentation, 3-dB down points were comparable for the notched-noise and bandlimiting methods. For NOS pi presentation, 3-dB down points were generally greater for the bandlimiting method than the notched noise method. Furthermore, for NOS pi presentation, the 3-dB down estimate increased as noise level increased for the bandlimiting method, but stayed constant for the notched-noise method. It is suggested that the two masking methods measured different aspects of binaural processing.

The ability to recognize synthetic, two-formant vowels with equal duration and similar loudness was measured in five subjects with the Cochlear and five subjects with the Symbion cochlear implants. In one set of test stimuli, vowel pairs differed only in the first-formant frequency (F1). In another set, vowel pairs differed only in the second-formant frequency (F2). When F1 differed, four of five Cochlear subjects and four of five Symbion subjects recognized the vowels significantly above chance. When F2 differed, two of five Cochlear subjects and three of five Symbion subjects scored above chance. These results suggest that implanted subjects can utilize both "place" information across different electrodes and "rate" information on a single electrode to derive information about the spectral content of the stimulus.

Frequency resolution and three tasks of frequency discrimination were measured at 500 and 4000 Hz in 12 normal and 12 hearing-impaired listeners. A three-interval, two-alternative forced-choice procedure was used. Frequency resolution was measured with an abbreviated psychoacoustical tuning curve. Frequency discrimination was measured for (1) a fixed-frequency standard and target, (2) a fixed-frequency standard and a frequency-transition target, and (3) frequency-transition standard and a frequency-transition target. The 50-ms frequency transitions had the same final frequency as the standards, but the initial frequency was lowered to obtain about 79% discrimination performance. There was a strong relationship between poor frequency resolution and elevated pure-tone thresholds, but only a very weak relationship between poor frequency discrimination and elevated pure-tone thresholds. Several hearing-impaired listeners had normal discrimination performance together with pure-tone thresholds of 80-90 dB HL. A slight correlation was found between word recognition and frequency discrimination, but a detailed comparison of the phonetic errors and either the frequency-discrimination or frequency-resolution tasks failed to suggest any consistent interdependencies. These results are consistent with previous work that has suggested that frequency resolution and frequency discrimination are independent processes.

This experiment investigated some interactions between combination tones (CT) and unmasking. Data were obtained from nine normal-hearing listeners in a forward-masking paradigm in which a 2000-Hz, 35-dB SPL masker preceded a 2000-Hz test signal. An adaptive, three-interval forced-choice procedure was employed to estimate the threshold for the test signal. This measurement provided a baseline. When a second sinusoid, the suppressor, of variable frequency and 55 dB SPL was presented concurrently with the masker, the amount of masking could be less than in the baseline condition. This two-tone unmasking was observed when the suppressor was approximately 2300 Hz. In the cubic difference tone (CDT) condition, two higher-frequency sinusoids of 80 dB SPL (with the lower frequency fixed at 2800 Hz) were added to the masker. In the difference tone (DT) condition, two higher-frequency sinusoids of 100 dB SPL (with the lower frequency fixed at 3500 Hz) were added to the masker. None of these sinusoids produced unmasking when presented individually, but when the CDT and DT were approximately 2300 Hz, unmasking was observed. The unmasking produced by the CTs was similar in its frequency characteristics to that of the single, suppressor tone. These results indicate that unmasking can be produced by CTs, just as if CTs were present in the stimulus. These data indirectly support the notion that CTs may be present in the form of traveling waves propagated along the basilar membrane.