Analysis of Clinical Tools Used for Hyperacusis Assessment: A Systematic Review and Meta-Analysis

Woojae Han; Gyungsik Jeon; Gibbeum Kim

doi:10.21848/asr.250186

Audiology and Speech Research > Volume 21(2); 2025 > Article

Han, Jeon, and Kim: Analysis of Clinical Tools Used for Hyperacusis Assessment: A Systematic Review and Meta-Analysis

Review Paper

Audiol Speech Res 2025;21(2):88-107.

Published online: April 30, 2025

DOI: https://doi.org/10.21848/asr.250186

Analysis of Clinical Tools Used for Hyperacusis Assessment: A Systematic Review and Meta-Analysis

Woojae Han^1,^2,³

, Gyungsik Jeon^1,²

, Gibbeum Kim^1,^3,⁴

¹Laboratory of Hearing and Technology, Research Institute of Audiology and Speech Pathology, Hallym University, Chuncheon, Korea

²Division of Speech Pathology and Audiology, College of Natural Sciences, Hallym University, Chuncheon, Korea

³Department of Speech and Hearing Science, College of Applied Health Science, University of Illinois at Urbana-Champaign, Champaign, IL, USA

⁴Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Champaign, IL, USA

Correspondence: Woojae Han, PhD Division of Speech Pathology and Audiology, College of Natural Sciences, Hallym University, 1 Hallymdaehak-gil, Chuncheon 24252, Korea
Tel: +82-33-248-2216 Fax: +82-33-256-3420 E-mail: woojaehan@hallym.ac.kr

Received April 15, 2025 Revised April 16, 2025 Accepted April 16, 2025

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Hyperacusis remains a misunderstood and often confusing hearing disorder that is complicated by a lack of consensus about how best to diagnose it and characterize its severity. This study reviews the clinical tools currently available for loudness hyperacusis by applying a systematic search and meta-analysis technique to identify a more reliable testing method. From the systematic review of electronic journal databases, nine studies and 14 studies met our inclusion criteria for hyperacusis questionnaires and for behavioral loudness measurement, respectively. Meta-analysis was also conducted to determine the most critical testing frequency that evaluates the loudness discomfort levels (LDL) by using data extracted from 1,783 subjects (1,548 for hyperacusis and 235 for normal hearing function). The effect size for LDL values was estimated using the mean and standard deviation for the hyperacusis group and the control group. The 10 questionnaires selected from nine studies varied in the number of questions in four typical subcategories (physical, attentional/perceptual, emotional, and behavioral/social). In the meta-analysis, individuals with hyperacusis had significantly lower LDL levels compared to the controls. Although there were no significant differences between two groups as a function of testing frequencies, we found a notable trend at LDL of 2 kHz with standardized mean difference and descriptive analysis. Due to the heterogeneity of the questionnaires, we suggest that the clinician should choose the appropriate questionnaire based on the functional impact of hyperacusis. In addition, when measuring LDL in hyperacusis, it is clinically efficient to first measure at 2 kHz.

Key Words: Hyperacusis, Questionnaire, Loudness discomfort level, Audiological test

INTRODUCTION

Although people with normal hearing sensitivity are comfortable listening to slightly loud environmental sounds, people who are sensitive to even small changes in volume tend to avoid them (Tyler et al., 2014). The combined meaning of “abnormally excessive” from hyper and “sound” from acusis, is clinically called “hyperacusis” and refers to abnormal intolerance to ordinary environmental sounds, or a disorder in loudness perception (Shi et al., 2022). People with loudness hyperacusis generally have loudness discomfort level (LDL) of 90 dB HL or less at two or more frequencies and reduced dynamic range of 55 dB or less (Sheldrake et al., 2015). Unfortunately, hyperacusis remains a misunderstood and confusing hearing disorder, making it difficult to achieve consensus on how to diagnose it and how to best characterize its severity (Fackrell et al., 2017).

There is still no effective treatment for patients with hyperacusis because its pathophysiologic causes and the range of influence expressed by an individual have not been clearly defined (Fackrell et al., 2017; Parmar & Prabhu, 2023). One reason is the dispute over where hyperacusis originates in terms of its etiology and pathological lesion. Radziwon & Salvi(2020) confirmed in experimental rats that hyperacusis might be caused by cochlear loss, including damaged outer hair cells and degeneration of the cochlear nerve. Another animal study done by Auerbach et al.(2019) induced temporary hearing loss and hyperacusis by salicylate administration and found that the central auditory system compensated for peripheral hearing loss (i.e., decreased peripheral input) with enhancement of and changes to loudness perception in what is called central gain (Tyler et al., 2014). They concluded that loudness perception would be more central than peripheral perception.

In terms of clinical studies, contemporary researchers have discussed how to differentiate hyperacusis from misophonia, another sound tolerance disorder (Tyler et al., 2014, Parmar & Prabhu, 2023). Hyperacusis is usually limited to conditions associated with auditory stimuli possibly caused by a central gain change of the auditory system independent of environmental influences (Tyler et al., 2014). People with hyperacusis sometimes also experience aural fullness, tinnitus, discomfort, and pain. In contrast, misophonia can be classified as a neurophysiological and behavioral condition where there is a conditioned simultaneous or sequential reflex response to auditory and visual stimuli (Ferrer-Torres & Giménez-Llort, 2022). It is often associated with anger, aversion, and anxiety, producing rage, sweating, and a high heart rate as part of the nervous system response. Unlike patients with hyperacusis, patients with misophonia who have normal hearing thresholds and a dynamic range seem to be influenced by their environment (Pellicori, 2020). However, clinicians sometimes confuse these two disorders, and thus fail to select and administer questionnaires to evaluate the key problems of hyperacusis. They also have difficulty diagnosing hyperacusis and distinguishing it from comorbid conditions of tinnitus and/or hearing loss.

We argue that there remains a need for an efficient protocol for diagnosing hyperacusis. For example, these protocols would include a standardized questionnaire (Parmar & Prabhu, 2023) and a clinical, not “theoretical” procedure that requires first selecting a frequency for LDL measurement to save time, rather than testing both ears at multiple frequencies (Punch et al., 2004). In other words, it is necessary to accurately evaluate patients with hyperacusis by creating standards or rules for the various testing frequencies currently measured in clinical practice, and also the characteristics of currently used screening tests and diagnostic questionnaires must be clearly analyzed so that clinicians can understand patients with hyperacusis.

The present study aimed to analyze the clinical evaluation tools currently used to diagnose the presence of hyperacusis accurately and efficiently and to suggest recommendations on the further clinical research. We focused on 1) whether the developed questionnaires effectively describe the characteristics of hyperacusis and 2) what the best frequency is for measuring LDL in patients with suspected hyperacusis. By examining questionnaires and LDL, this systematic review and meta-analysis provide a clear perspective on necessary future research and generate hypotheses for further study.

MATERIALS AND METHODS

Questionnaire

Search strategy and article selection

To review the prospective studies that contributed to the development of hyperacusis questionnaires, five electronic journal databases (ScienceDirect, Web of Science, PubMed, Medline, and CINAHL) were searched in December 2024. Key search terms were “hyperacusis” OR “sound intolerance” OR “loudness discomfort” OR “uncomfortable loudness” OR “hypersensitivity to sound” OR “noise avoidance” AND “questionnaire” OR “self-report”.

Studies meeting the following inclusion criteria were included: 1) developed to screen for hyperacusis; 2) developed to diagnose the severity of hyperacusis; 3) self- or interviewer-based questionnaires; 4) published in English; and 5) randomized controlled trials, non-randomized controlled trials, or cohort studies.

Using these search criteria, 8,544 articles were initially found in the databases. Of these, 493 duplicated articles were removed. Then, 7,920 of the remaining 8,051 articles were excluded because they were animal studies, case reports, guidelines, review papers, and books, although two independent authors (W.H. and G.J.) screened the titles and abstracts. They also independently extracted data from each of the included studies. Discrepancies were resolved through discussion and meetings with a third author (G.K.). The following data were extracted and synthesized: author, year, title and purpose of the questionnaire, methods, number of items, scoring criteria, and methods for interpreting results. After carefully reviewing the full texts of the 131 articles, we found that 122 were unrelated to the development and/or standardization of the hyperacusis questionnaire resulting in a final sample of nine papers. Figure 1 displays a flow chart of this search processes.

LDL

Search strategy and article selection

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (Moher et al.. 2015), the initial systematic review was conducted in January 2025, to identify the significant LDL as a function of frequency. We searched articles published from 1996, when Goldstein & Shulman(1996) first measured LDL for hyperacusis, using seven electronic journal databases: ScienceDirect, Web of Knowledge, CINAHL, PubMed, Medline, Cochran, and Scopus. A string of search keywords included “hyperacusis” OR “hypersensitivity to sound” OR “high sensitivity to sound” AND “loudness discomfort (level)” OR “loudness measurement” OR “uncomfortable loudness (level)”.

Based on the Figure 2, a total of 12,872 articles were initially identified in the database. After excluding 12,643 papers due to several reasons, two authors (W.H. and G.J.) evaluated the full text of 46 articles by using the participants, interventions, comparisons, outcomes, and study design (PICOS) criteria. Disagreements were fully discussed and agreed upon before we moved to the next stage. Finally, 14 papers were included for a qualitative analysis through these screening and eligibility processes.

Selection criteria of study

The inclusion criteria for these studies were specified as per PICOS. Participants were children and adults with hyperacusis, loudness discomfort, and high sensitivity to sound. The participants did not receive any intervention. For the comparison group, individuals with normal loudness sensitivity to sound without intervention (voluntarily selfreport or >95 dB HL) were included. Studies were included if their outcomes incorporated loudness measurement (in decibels) in the testing frequency using pure-tone stimuli. Study designs of randomized controlled trials, non-randomized controlled trials, and cohort studies were included.

Analysis of study quality

The Newcastle-Ottawa scale (Stang, 2010) having three subcategories (selection, comparability, and outcomes) and eight items in total was applied to assess the study quality of 14 articles. In Table 1, six of the selected studies had “good” quality (scores of 7~8) and the remaining studies had “fair” quality (scores of 4~6). Thus, all the articles were included for a systematic review and meta-analysis for LDL measurement. Data extraction and statistical analysis

Two authors (W.H. and G.J.) independently extracted data from each study following the PICOS criteria. After confirming whether a total of 20 pieces of data that were extracted and synthesized from 14 articles included were suitable for meta-analysis, the analysis was conducted using R software version 4.2.2 (R Foundation for Statistical Computing, Vienna, Austria). The effect size for LDL values was estimated using the mean and standard deviation for the hyperacusis group and the control group. However, because the measurement method used to measure was different, standardized mean difference (SMD) was also applied to estimate the effect size and then verified in the random effects model at the 95% confidence interval (CI).

Publication bias was confirmed through the funnel plot and significant probability of Egger's regression asymmetry test (p < 0.05). In addition, based on the Cochrane's Q test and Higgins I² statistics, the heterogeneity of the variance between each literature was also confirmed (p < 0.05).

RESULTS

Questionnaire

Study characteristics

One of these nine papers had two questionnaires (Aazh et al., 2021), so Table 2 summarizes the characteristics of 10 questionnaires used in the clinics and experimental designs. Seven of the 10 questionnaires were suitable for screening purposes because people who might have hyperacusis could have confirmed it as either present or absent depending on the questionnaire score. However, the interpretation of these results was unclear in studies by Ke et al.(2020) and Ascone et al.(2019). The other three questionnaires might confirm the severity of hyperacusis. For example, multiple-activity scale for hyperacusis (MASH) (Dauman & Bouscau-Faure, 2005), Geräuschüberempfindlichkeits-Fragebogen (GUF) (Bläsing et al., 2010), and inventory of hyperacusis symptoms (IHS) (Greenberg & Carlos, 2018) indicated that the higher the total score, the more severe the hyperacusis.

Analysis of the questionnaire contents

For a still deeper understanding, 161 items (or questions) extracted from 10 questionnaires were classified into four new categories: physical, attentional/perceptual, emotional, and behavioral/social aspects since most experts mentioned these categories as characteristics of hyperacusis (Ke et al., 2020; Tyler et al., 2014). In detail, the physical category included the questions about sensory changes, such as ear pain and problem with balance and odor. The attentional/perceptual category had items on high/hypersensitivity to sound stimuli and background noise for loudness. The emotional category included anxiety, anger, stress, and aversion. The behavioral/social category consisted of items effects of hyperacusis, such as negative influences on relationships with family and/or friends and intentional (or not) limitations and restrictions (Fackrell et al., 2017). Then, each category was decomposed into 16 subcategories based on similar content.

Figure 3 visually depicts the characteristics of the 10 questionnaires according to our analysis of the categories and their items. The total number of items included in each questionnaire was shown on the Y-axis (maximum number is 25). X-axis represents a kind of questionnaire. Hyperacusis handicap questionnaire (HHQ), hyperacusis intake questionnaire (HintakeQ), IHS, and noise avoidance questionnaire (NAQ) are long questionnaires; the sound sensitivity symptoms questionnaire (SSSQ), hyperacusis impact questionnaire (HimpactQ), and sensitivity to infra-sound and ultra-sound questionnaire (SISUS-Q) questionnaires are shorter. Upon closer examination, the categories composed from each questionnaire appeared very different in content and distribution although each had its own purpose and method. For instance, MASH has an emotional aspect (blue block) in all 14 items, whereas NAQ is limited to items related to the behavioral/social aspect (green block). In HintakeQ, the physical aspect is included in 19 out of 23 items (grey block), with no questions about the behavioral/social aspect. In sum, because the heterogeneity among the questionnaires seems to be very high in terms of category, researchers or clinicians should carefully identify the subcategories and items of a questionnaire and use it according to their screening or diagnostic purpose.

International application of questionnaires in various languages

The questionnaire developed by Khalfa et al.(2002) has been translated into Arabic (Shabana et al., 2011), Turkish (Erinc & Derinsu, 2022), Norwegian (Larsen et al., 2021), Persian (Kashani et al., 2022), Portuguese (Bastos & Ganz Sanchez, 2017), Dutch (Meeus et al., 2010), Italian (Fioretti et al., 2015; Tortorella et al., 2017), Japanese (Oishi et al., 2017; Yamada et al., 2022), and Swedish (Blomberg et al., 2006). After translating it into their native language, the authors checked the internal consistency for how closely related the items were to the patients with hyperacusis and compared their translated version to the original, including audiological measurements such as pure tone audiometry and loudness discomfort level. Most researchers agreed that both the original and its translation had good internal consistency and reliability that would not be significantly affected by cultural differences (Larsen et al., 2021) although several papers did report some flaws, such as hyperacusis questionnaire (HQ) item 11 (Erinc & Derinsu, 2022), but small changes in HQ items 11 and 14 to maintain the original meaning (Kashani et al., 2022), and low internal consistency in HQ items 1, 5, 6, and 11 (Yamada et al., 2022). In addition, a difference that did originate in the characteristics of the participants may affect interpretation of the scores (Bastos & Ganz Sanchez, 2017; Fioretti et al., 2015; Oishi et al., 2017; Yamada et al., 2022), which must be carefully considered. Khalfa et al.(2002) gathered data from the general population who were not previously diagnosed with hyperacusis; other researchers used patients in a clinic (Bastos & Ganz Sanchez, 2017) or who were complaining of tinnitus (Fioretti et al., 2015) or hearing loss and/or hyperacusis (Oishi et al., 2017; Yamada et al., 2022).

On the other hand, HimpactQ (Aazh et al., 2021) was developed into a Dutch version (Keppler et al., 2022) and GUF (Bläsing et al., 2010) was translated into Spanish (Herráiz et al., 2006). Unfortunately, there have been few internationally recognized and standardized screening and diagnostic questionnaires for hyperacusis.

Loudness discomfort levels

Characteristics of studies on LDL

Table 3 summarizes the characteristics of the 14 articles. Most articles were randomized controlled trials and retrospective analysis. When classified according to the characteristics of the study subjects, there were seven papers on hyperacusis, one paper on normal hearing, and six papers that included both groups. Although the study subjects were mainly adults in their 20s to 50s, the participants of Silverstein et al.(2016) and Aazh et al.(2018) were over 60 years old and 12 years old, respectively.

For the testing frequency, LDL measurement was between 0.25 and 8 kHz (octave and/or half-octave interval) in most studies, except for Diehl & Schaette(2015) and Sheldrake et al.(2015) where they were measured at 125 Hz. Some studies additionally tested LDL at 3 kHz and/or 6 kHz only for hyperacusis.

According to our inclusion criteria, studies using only pure tones as the stimuli were included for the meta-analysis. Table 4 notes LDLs as the testing frequency for hyperacusis and control groups from the studies. As we expected, the control group with normal sensitivity scored a higher LDL than did the group of patients with hyperacusis. The LDL of the control group was recorded at 100 to 115 dB HL across the testing frequency, while that of patients with hyperacusis was measured at 75 to 90 dB HL. However, Enzler et al.(2021) showed an unusually low LDL of 87.36 dB HL at 4 kHz and 82.66 dB HL at 8 kHz, even for the group with normal sensitivity. A study by Huang et al.(2023) showed LDL from 99.76 to 109.37 dB HL for hyperacusis and from 102.18 to 114.26 dB HL for normal sensitivity, thereby indicating no difference between the two groups.

Results of the meta-analysis

In a pooled analysis, the LDL of the patients with hyperacusis was significantly lower than the LDL of those with normal sensitivity function (SMD, –2.3615; 95% CI, –3.1405 to –1.5825; p < 0.001). However, the funnel plot was asymmetric and the Egger's regression test also detected publication bias in the studies (t = –5.43; p < 0.0001). Due to that high heterogeneity (I² = 96.31%; Q = 700.48; p < 0.0001), we conducted a subgroup analysis for the test frequency.

A subgroup analysis of six testing frequencies (0.25, 0.5, 1, 2, 3, 4, and 8 kHz) was performed to investigate which frequencies were most sensitive to LDL measurements in the hyperacusis. Figure 4 presents the forest plots and effect sizes for the subgroups, 95% CIs, and heterogeneity. Although the hyperacusis group had overall lower LDL levels than the control group, there was no significant group difference in LDL level (Q = 1.70; df = 5; p = 0.8895). The largest difference in LDL between the two groups was at 2 kHz (SMD, –2.7525), followed by 4 kHz (SMD, –2.7505), 1 kHz (SMD, –2.4644), 0.5 kHz (SMD, –2.3633), 8 kHz (SMD, –1.6882), and 0.25 kHz (SMD, –1.5502).

Using a descriptive statistical analysis, it was noted that the average LDL of each frequency in patients with hyperacusis was 82.74 (9.26), 84.95 (11.55), 85.77 (11.52), 84.43 (12.29), 82.67 (13.31), and 79.20 (14.60) dB HL for 0.25, 0.5, 1, 2, 4, and 8 kHz, respectively. In comparison, the average LDL for each frequency in the control group was 102.18 (6.37), 105.85 (7.96), 107.93 (7.18), 107.69 (7.65), 103.24 (8.70), and 97.23 (8.39) dB HL for 0.25, 0.5, 1, 2, 4, and 8 kHz, respectively. In the Figure 5, the two frequencies that exhibited the largest differences in LDL between the two groups were 2 kHz, with a difference of 23.25 dB, and 1 kHz, with a difference of 22.15 dB.

DISCUSSIONS

To identify currently used clinical assessment tools for the hyperacusis diagnosis, this study had focused on a questionnaire and loudness discomfort level with the research questions followed.

Do the developed questionnaires describe the characteristics of hyperacusis as well as their purpose?

About 10 questionnaires are now being used clinically and in research. However, there is no way of knowing which is most appropriate when asking about the characteristics of hyperacusis patients and presenting their problem. In other words, after an examination of the questionnaires found through systematic searching, seven questionnaires could screen patients for hyperacusis, and the remaining three could distinguish mild, moderate, substantial, and severe cases. As such differences should be understood, the questionnaires must be selected based on the clinician or researcher's specific purpose (Fackrell et al., 2017).

A recent publication of Kula et al.(2022), similar to our study, conducted a systematic review using COSMIN criteria to assess the psychometric properties of hyperacusis questionnaires; however, they only included five published studies and missed newly-developed questionnaires. By adding these missing papers, our study has updated all developed hyperacusis questionnaires to date. Furthermore, in the present study, we subcategorized the questions into four groups. This unique approach helps evaluate whether current questionnaires effectively capture features of loudness hyperacusis.

Tyler et al.(2014) have proposed four subtypes of hyperacusis: 1) loudness hyperacusis, where moderately loud sounds cause discomfort; 2) annoyance hyperacusis, characterized by a negative emotional reaction to sounds; 3) fear hyperacusis, which involves an aversive response to sounds; and 4) pain hyperacusis, where individuals experience pain at much lower sound levels than those with normal hearing. Despite these classifications, quantitative data on the prevalence and co-occurrence of each subtype remains limited (Fackrell et al., 2017). Loudness hyperacusis often coexists with strong emotional reactions, such as annoyance (annoyance hyperacusis) or fear (fear hyperacusis), suggesting an overlap of these dimensions (Salvi et al., 2022). The items in the four subcategories of hyperacusis that we analyzed were distributed evenly based on the questionnaire, but sometimes concentrated on one or two subcategories. Of course, we understand that the questionnaires varied in content and structure because they had different developmental purposes, so it is difficult to say which questionnaire was most accurate in evaluating hyperacusis. Simply put, HHQ and IHS were very similar in the number of questions and content of subcategories. Although there were fewer questions, this pattern can be confirmed in the HQ, GUF, SISUS-Q, and SSSQ. When a clinician wants to pinpoint the emotions of a patient with hyperacusis, MASH would be appropriate; however, when a clinician wants to check a patient’s behavioral/social aspects, the NAQ questionnaire might be better. Therefore, clinicians and researchers should select a questionnaire based on its purpose and subcategories. For example, the assumption in the questionnaire is that the diagnosis is loudness hyperacusis and not some other type, so it is important to make sure that the questions pertain to loudness hyperacusis. Unfortunately, many hyperacusis questionnaires ask questions that are more suited to for people with misophonia, and their answers may affect the total score. Audiologists should discuss this concern.

In terms of international use, we confirmed that the hyperacusis questionnaire developed by Kalfa et al.(2002), was the most representative. It was neither too long nor too short, and all the characteristics of hyperacusis except for physical were noted. However, when including verification through simple language translation/back-translation, the contents and items of a questionnaire must undergo standardization processes to include all the hyperacusis characteristics well (Ascone et al., 2019; Bläsing et al., 2010; Khalfa et al., 2002). Furthermore, it will be more useful to both clinicians and patients if several questionnaires, including those with items not included in the K-HQ, are translated.

What is the most effective frequency for measuring LDL in patients suspected of having hyperacusis?

There are no universally accepted standards for assessing the effects of hyperacusis (Fackrell et al., 2017). Nevertheless, when a patient present with possible hyperacusis, the audiologist should measure LDL at a frequency from 0.25 to 8 kHz with an octave interval in both ears (Keidser et al., 1999). As we mentioned earlier, measuring at the most reliable frequency for diagnosing hyperacusis through LDL measurement, which differentiates the patient from any controls, saves time and the audiologist with reliable results (Punch et al., 2004).

Unfortunately, statistical significance by the test frequency could not be confirmed in our meta-analysis results, which were analyzed using data from 14 previous studies. However, when compared to the control group, the SMD was the highest as –2.7525 at 2 kHz and the frequency with the largest difference in the descriptive mean at 23.26 dB HL was 2 kHz. This finding is confirmed in Figure 1 of the study by Vidal et al.(2022) while providing a notch at 2 kHz of LDL for hyperacusis (group 3). Even though it is a different assessment tool, the middle latency response (MLR) study by Formby et al.(2017) also predicted a sensitivity of 2 kHz as an important frequency for hyperacusis, given as a comparison of pre- and post-sound therapy, MLR latencies for all three study subjects (hyperacusis with hearing loss) significantly changed at 2 kHz. Their findings showed that the latencies before sound treatment were consistently shorter than the control values, while the latencies after treatment were consistently longer (Formby et al., 2017).

We propose that the difference at 4 kHz (meta-analysis) and/or 1 kHz (descriptive mean) was found to be largest in the next order. However, because many patients with hyperacusis often have hearing loss and tinnitus (Blaesing & Kroener-Herwig, 2012; Ke et al., 2020), it is expected that a level of 1 kHz will provide more stable results than a level of 4 kHz. For the most efficient way to test, we suggest first measuring LDL in hyperacusis patients at 2 kHz and then at 1 kHz instead of 4 kHz, if there is hearing loss at high frequency. Regardless, to supplement and generalize the meta-analysis results of the studies to date, it is necessary to check the test-retest reliability of LDL by its frequency in patients with hyperacusis. Thus, future studies on LDL sensitivity and specificity these patients should be well designed and include a verification of the order of testing frequency.

Limitation of current study

This study analyzed the clinical diagnostic tools used in patients with hyperacusis and identified the most effective, based on previous studies. As noted earlier, it is difficult to draw definitive conclusions because most of the studies were conducted on patients with other conditions in addition to hyperacusis (Prabhu & Nagaraj, 2020). In other words, there is still a clear controversy over the separation of the characteristics of patients with loudness hyperacusis alone. Hyperacusis can occur alone, but it is highly comorbid with several conditions, including genetic disorders (e.g., Williams syndrome), hearing disorders (e.g., tinnitus), neurological problems (e.g., migraine), and neurodevelopmental syndromes (autism spectrum disorder). Furthermore, hyperacusis can occur without clinically loss of hearing thresholds (Zeng, 2013). Despite widespread knowledge of hyperacusis as being commonly associated with these comorbid conditions, the empirical evidence substantiating these links remains poorly understood.

Moreover, there were limitations to discussing the characteristics of hyperacusis according to patients’ age and gender (Khalfa et al., 2002). We expect that the limitations of this current study will be addressed through followup research on the characteristics of hyperacusis and the likelihood of common comorbidities according to age and the classification of hyperacusis as a single condition.

Recommendation and future direction

The gold standard may be a structured interview by clinicians with the assistance of the questionnaires and LDLs. It is recommended that the clinicians select and use an appropriate questionnaire depending on the purpose and also measure LDL for a more comprehensive interpretation. If a patient shows low LDL and high scores of questionnaires, hyperacusis may be suspected (Jüris et al., 2013). At the same time, if the patient shows high LDL and low scores on questionnaires, hyperacusis can be ruled out. However, if a patient shows high LDL and high scores on questionnaires, or low LDL and low scores of questionnaires, there is a need to discuss how to interpret this information and how to follow up. Previous studies have shown that the severity of hyperacusis was not associated with loudness (Aazh & Moore, 2017). In other words, interpretations that do not match or confirm the results of the questionnaire and the discomfort level are still possible in the clinic, and it might be worthwhile to explore this in future research.

In the future, researchers will need to look more closely at patients with low LDL and high scores on questionnaires, and thereby find the best hallmarks, such as using auditory brainstem response (ABR) testing and brain imaging techniques (Jahn, 2022). That is, considerations related to the mechanism of hyperacusis must be better documented before objective tools like ABR and fMRI can be used, based on the scientific evidence.

However, there are few ABR measurements for patients with hyperacusis confirmed through our systematic search, which found only four studies. Most of these studies were conducted on patients with co-morbidities. The studies to date do not allow for clear conclusions because most management strategies have been based on patients who report hypersensitivity as a secondary symptom or as part of a symptom set (Fackrell et al., 2017). Moreover, due to the nature of ABR, classification and analysis based on age must also be performed, but too few studies have been conducted thus far. It would thus be beneficial for many clinicians and patients alike if an objective screening tool, along with a questionnaire and behavioral measurement of LDL, could serve as an effective battery of tests to identify their problems accurately and allow for better treatment options.

In conclusion, our paper emphasizes the need to develop and validate more robust assessment tools for diagnosing hyperacusis in clinical settings. We recommend a standardized protocol that combines objective and subjective measures for broad clinical application, which is also crucial for developing treatments and rehabilitation guidelines.

Notes

Ethical Statement

N/A

Acknowledgements

N/A

Declaration of Conflicting Interests

The authors have no conflicts of interest to declare.

Funding

This work was supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea (NRF-2022S1A5A2A01044793).

Author Contributions

Conceptualization: Woojae Han. Data acquisition and formal analysis: Woojae Han, Gyungsik Jeon, and Gibbeum Kim. Funding acquisition: Woojae Han. Methodology: Woojae Han and Gyungsik Jeon. Project administration: Woojae Han. Visualization: Gyungsik Jeon and Gibbeum Kim. Writing—original draft: Woojae Han and Gyungsik Jeon. Writing—review & editing: All authors.

Figure 1.

Flow diagram of the studies for hyperacusis questionnaire selected for the systematic review and based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria.

Figure 2.

Flow diagram of the studies for loudness discomfort levels selected for the systematic review and based on the PRISMA criteria. Applying the PICOS criteria to the 46 full-text eligible articles, resulted in 14 studies that were included in further qualitative and quantitative meta-analysis. PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses, PICOS: participants, interventions, comparisons, outcomes and study design.

Figure 3.

A graphical analysis of 10 hyperacusis questionnaires currently used in the clinical and research fields as a function of four categories: physical, attentional/perceptual, emotional, behavioral/social. The X-axis has 10 questionnaires and the Y-axis represents a total number of items per each questionnaire. SSSQ: sound sensitivity symptoms questionnaire, HimpactQ: hyperacusis impact questionnaire, SISUS-Q: sensitivity to nfra-sound and ultra-sound questionnaire, MASH: mutiple-activity scale for hyperacusis, K-HQ: hyperacusis questionnaire developed by Khalfa et al., GUF: questionnaire on hypersensitivity to sound, HHQ: hyperacusis handicap questionnaire, HintakeQ: hyperacusis intake questionnaire, NAQ: noise avoidance questionnaire, IHS: inventory of hyperacusis symptoms.

Figure 4.

Forest plots for a subgroup analysis based on six testing frequencies ranged from 0.25 kHz to 8 kHz. SD: standard deviation, SMD: standard mean difference, CI: confidence interval.

Figure 5.

A group comparison of LDL values between hyperacusis patients and group with normal sensitivity function as a function of frequency. Error bar refers to standard deviations. LDL: loudness discomfort levels.

Table 1.

Comparison of key features on 10 hyperacusis questionnaires from nine studies found through the systematic review of the literature

Study	Title of questionnaire	Primary purpose	Methods	Contents	Scoring	Interpretation of results
Khalfa et al. (2002)	-Hyperacusis	Screening	Self-rating	-Three subcategories	-Total: 56	-Absent, 0~28.4
Khalfa et al. (2002)	-Questionnaire	Screening	Self-rating	-14 items	-Four-point scale (0: no; 1: a little; 2: quite a lot; and 3: a lot)	-Present, 28.5~56
Dauman & Bouscau-Faure (2005)	Multiple-activity scale for hyperacusis	Severity	Interview	14 items	-Total: 10 (on average)	-Absent or mild, 0~3
					-0~10 scales (0: no problem and 10: unbearable)	-Moderate, 3.1~5.0
						-Substantial, 5.1~7.0
						-Severe, 7.1~10
Bläsing et al. (2010)	Questionnaire on hypersensitivity to sound	Severity	Self-report	15 items	-Total: 45	-Absent or mild, 0~9
					-Four-point scales (0: never correct; 1: sometimes correct; 2: often correct; 3: always correct)	-Moderate, 10~15
						-Substantial, 16~23
						-Severe, 24~45
Blaesing & Kroener-Herwig (2012)	Noise avoidance questionnaire	Screening	Self-rating	25 items	-Total: 100	-Absent, 6.1 ± 6.34
Blaesing & Kroener-Herwig (2012)	Noise avoidance questionnaire	Screening	Self-rating	25 items	-Five-point scales (0: never; 1: rarely; 2: occasionally/sometimes; 3: often; 4: very often/always)	-Present, 38.54 ± 19.57
Greenberg & Carlos (2018)	Inventory of hyperacusis symptoms	Severity	Self-rating	25 items	-Total: 100	-Absent, 38.8~55.7
					-Four-point scales (1: not at all; 2: a little; 3: somewhat; 4: very much so)	-Mild, 50.4~57.0
						-Moderate, 66.8~70.5
						-Substantial, 78.9~81.7
						-Severe, 87.4~91.4
Ke et al. (2020)	Hyperacusis intake questionnaire	Screening	Interview	24 items	-Items 1, 11, 13, 15, 17 (0, strongly disagree~100, strongly agree)	N/A
					-Items 2, 4~9, and 18~24 (choose from selection)
					-Items 3, 10, 12, 14, and 16 (duration)
Ascone et al. (2019)	Sensitivity to infra-sound and ultra-sound questionnaire	Screening	Interview	-Four subcategories	-Total: 100	N/A
Ascone et al. (2019)	Sensitivity to infra-sound and ultra-sound questionnaire	Screening	Interview	-10 items	-0~25 scales (0: never~25: often/always)	N/A
Prabhu & Nagaraj (2020)	Hyperacusis handicap questionnaire	Screening	Self-rating	-Three subcategories-21 items	-Total: 84	Present: 20~50
Prabhu & Nagaraj (2020)	Hyperacusis handicap questionnaire	Screening	Self-rating	-Three subcategories-21 items	-Three-point scales (0: never; 2: sometimes; and 4: always)	Present: 20~50
Aazh et al. (2021)	-Hyperacusis impact questionnaire	-Screening	-Self-rating	-Eight items	-Total: 24	-Absent: 0~10
	-Sound sensitivity symptoms questionnaire	-Screening	-Self-rating	-Five items	-Four-point scale (0: 0~1 days; 1: 2~6 days; 2: 7~10 days; 3: 11~14 days)	-Present: 11~24
					-Total: 15	-Absent: 0~4.6
					-Four-point scale (0: 0~1 days; 1: 2~6 days; 2: 7~10 days; 3: 11~14 days)	-Present: 4.7~15

N/A: not applicable

Table 2.

Scientific study validity based on the Newcastle Ottawa Scale used for studies of loudness discomfort levels

Study	Quality assessment per the Newcastle Ottawa scale
Study	Selection	Comparability	Outcome	Total Scores
Hawley et al. (2007)	3	2	2	Good (7)
Jüris et al. (2013)	2	2	2	Fair (6)
Diehl & Schaette (2015)	3	1	3	Good (7)
Sheldrake et al. (2015)	2	2	3	Good (7)
Silverstein et al. (2016)	2	1	2	Fair (5)
Knudson & Melcher (2016)	2	1	2	Fair (5)
Aazh & Moore (2017)	2	1	2	Fair (5)
Aazh et al. (2018)	2	1	3	Fair (6)
Aazh et al. (2021)	2	2	2	Fair (6)
Enzler et al. (2021)	3	2	3	Good (8)
Erinc & Derinsu (2022)	3	2	2	Good (7)
Shin et al. (2022)	2	2	2	Fair (6)
Vidal et al. (2022)	2	2	3	Good (7)
Huang et al. (2023)	3	1	3	Good (7)

Overall study quality of this evaluation was arbitrarily defined as poor (score, 0~3), fair (4~6), or good (7~9).

Table 3.

Summary of key characteristics in 14 included studies

Study	Study design	Subjects			Measurement		Main findings
Study	Study design	Number/ group	Age (yr)	Gender	Frequency	Stimuli	Main findings
Hawley et al. (2007)	Retrospective analysis of anonymized data	-68 hyperacusis	-56 (15~75)	-29 F and 39 M	-1, 2, 4, and 8 kHz	Pure tone	Hyperacusis patients get resolved from TRT treatment. Hyperacusis in either ear decreased from 65 patients (95.6%) to 46 patients (67.6%) after receiving TRT. Most of the remaining hyperacusis patients (32 of 68 patients; 47%) were improved. 28% of the hyperacusis patients fully resolved and a larger percentage (79.4%) had improvements from TRT
Hawley et al. (2007)	Retrospective analysis of anonymized data	-58 tinnitus	-53 (15~75)	-14 F and 44 m	-1, 2, 4, and 8 kHz	Pure tone
Jüris et al. (2013)	Randomized controlled	62 hyperacusis	40.2 ± 12.2		0.25, 0.5, 1, 2, 3, and 4 kHz	Pure tone	Hyperacusis questionnaire significantly correlated with all LDL for right ear (except 4 kHz; p < 0.05) and not with left ear. Hospital anxiety and depression scale also correlated with LDL in both ears (except for 500 Hz in right ear; p < 0.05). Hyperacusis questionnaire cut off score should be lower about 24 points rather than 28 points
Diehl & Schaette (2015)	Retrospective analysis of anonymized data	-130 hyperacusis			0.125, 0.25, 0.5, 1, 2, 4, 6, and 8 kHz	Pure tone	Frequency-independent gain increase and frequency-specific gain increase in high-frequency range except for 0.125 and 8 kHz. This auditory gain mechanism can be the possibilities to explain the hyperacusis
Diehl & Schaette (2015)	Retrospective analysis of anonymized data	-13 normal			0.125, 0.25, 0.5, 1, 2, 4, 6, and 8 kHz	Pure tone
Sheldrake et al. (2015)	Retrospective analysis of anonymized data	381 hyperacusis	43.9 ± 15.0	170 F and 211 M	0.125, 0.25, 0.5, 1, 2, 4, 6, and 8 kHz	Pure tone	LDLs in people who complain hyperacusis were about 85 dB HL (78~87 dB HL). Compared to normative data, about 15.7~17.8 dB for 0.5~4 kHz was decreased. However, to diagnose hyperacusis by LDL and 90% correct classification should be followed around 40~50% of false positives
Silverstein et al. (2016)	Randomized controlled	6 hyperacusis	67.0 ± 9.0	4 F and 2 M	0.25, 0.5, 1, 2, 3, 4, and 8 kHz	Pure tone	Patients who had at least 3 months history of hyperacusis symptoms before enrollment were under surgery to reinforce round & oval window. There were no statistically improvement in ULL and HQ scores but participants said the overall quality of life was improved after treatment
Knudson & Melcher (2016)	Randomized controlled	-29 normal	34~63	-10 F and 19 M	-Broadband	-Noise	Acoustic startle response threshold and LDL was significantly correlated (noise, p < 0.0001 [noise, quiet background), 0.5 Hz warble tone, p = 0.0002 [noise background], p < 0.0001 [quiet background]) and acoustic startle response amplitude was greater in tinnitus group than no-tinnitus group. But there was no correlation with sound-level tolerance questionnaire
Knudson & Melcher (2016)	Randomized controlled	-23 tinnitus	34~63	-8 F and 15 M	-0.5 kHz	-Warble tone
Aazh & Moore (2017)	Retrospective analysis of anonymized data	573 hyperacusis with tinnitus	55.0 ± 17.0	300 F and 273 M	0.25, 0.5, 1, 2, 3, 4, 6, and 8 kHz	Pure tone	Significant correlation with ULL min valuess and pure tone audiometirc threshold (p < 0.0010); HQ (p < 0.001), tinnitus handicap inventory (p < 0.001), insomnia severity index (p = 0.0015), and age (p < 0.001). But no correlation with visual analogue scale score for tinnitus loudness (p < 0.46)
Aazh et al. (2018)	Retrospective analysis of anonymized data	62 hyperacusis	12.0 ± 4.1	30 F and 32 M	0.25, 0.5, 1, 2, 3, 4, 6, and 8 kHz	Pure tone	Young people who had severe hyperacusis shows 17.5 ± 15.0 dB lower ULL at 8 kHz than in 0.25 kHz, however it was only 7.5 ± 15.0 dB lower for remains but not significant difference was shown (p = 0.31). About 80% had pure tone audiograms and 85% of participants had hyperacusis under ULL min values ≤ 77 dB HL
Aazh et al. (2021)	Retrospective analysis of anonymized data	100 hyperacusis	55.0 ± 13.0		0.25, 0.5, 1, 2, 3, 4, 6, and 8 kHz	Pure tone	Total socre of inventory of hyperacusis symptoms had weekely negative correlation with ULL min values and ULL across ears (r = –0.21 and -0.22). And had moderate correlation with HQ scores, tinnitus handicap inventory, generalized anxiety disorder-7 and patient health questionnaire-9 (r = 0.58, 0.58, 0.61, and 0.54). Inventory of hyperacusis symptoms’ cutoff value should be
Enzler et al. (2021)	Randomized controlled	-27 hyperacusis-54 normal	-41.0 ± 15.0	-14 F and 13 M	0.5, 4, and 8 kHz	Tone pips	New assessment tool for hyperacusis was developed, core discriminant score (CDS) which use natural sounds. CDS is stronger assessment than other hyperacusis measurement (area under curve of ROC, 0.835)
Enzler et al. (2021)	Randomized controlled	-27 hyperacusis-54 normal	-33.0 ± 15.0	-30 F and 24 M	0.5, 4, and 8 kHz	Tone pips
Erinc & Derinsu (2022)	Randomized controlled	-20 hyperacusis	-39.8 ± 11.8	-10 F and 10 M	-0.5, 1, 2, 4, and 8 kHz	-Pure tone	Tinnitus handicap inventory, visual analogue scale annoyance, effect on life score in hyperacusis group were significantly higher than tinnitus group (p = 0.002, < 0.001, and 0.005). In HQ score, there were significant relationship between three groups (control & tinnitus, p = 0.027; control & hyperacusis, p < 0.001, and tinnitus & hyperacusis, p < 0.001). In LDL, hyperacusis and other two groups had significant difference (p < 0.001). There was significant difference between tinnitus and hyperacusis in 500 Hz FRESH noise (p = 0.024)
		-20 tinnitus	-40.9 ± 12.2	-10 F and 10 M	-0.5 and 2 kHz	-Frequency specific hearing assessment (FRESH) noise
		-20 normal	-38.7 ± 14.6	-13 F and 7 M	-0.5 and 2 kHz	-Frequency specific hearing assessment (FRESH) noise
Shin et al. (2022)	Retrospective analysis of anonymized data	-51 hyperacusis	-46.9 ± 14.5	100 F and 94 M	0.25, 0.5~8 kHz	Pure tone	Hyperacusis patients had higher tinnitus handicap inventory scores (p = 0.002), NRS scores for tinnitus awareness (p = 0.032), and lower LDLs (p < 0.010) on both ears than patients without hyperacusis. Higher tinnitus handicap inventory associated with co-occurrence of subjective hyperacusis and tinnitus (p = 0.009). Increased beta-PSD (p = 0.016), decreased gamma-PSD (p < 0.001) were shown in hyperacusis patients and reduced level of all-ERSP, delta-ERSP observed (p < 0.001)
Shin et al. (2022)	Retrospective analysis of anonymized data	-143 without hyperacusis	-54.3 ± 15.0	100 F and 94 M	0.25, 0.5~8 kHz	Pure tone
Vidal et al. (2022)	Randomized crossover	-21 hyperacusis	-46.9 ± 13.6	-6 F and 9 M	0.125, 0.25, 0.25, 0.5, 1, 2, 4, 6, and 8 kHz	-WBN	Hyperacusis patients shows significantly low LDLs (pure tone, 74 dB ± 2.96; WBN, 45.1 dB ± 12.1) compared to other groups (p < 0.01). Also, after using 6 month of sound generator, the average of LDLs significantly decreases (p = 0.02)
		-20 normal	-55.9 ± 7.9	-8 F and 4 M		-Pure tone
		-15 tinnitus	-47.9 ± 11.0	-11 F and 10 M
		-12 tinnitus with HL	-31.6 ± 9.3	-10 F and 10 M
Huang et al. (2023)	Randomized controlled	-40 hyperacusis	-Less than 20 years: 5; 20~30 years: 16; 40~50 years: 15; and 60~70 years: 4	-33 F and 7 M	0.25, 0.5, 1, 2, 4, and 8 kHz	Pure tone	Self-report of feeling upset, pain and anxiety/fear were 95%, 65%, and 82.5% each. Also, LDL shows significant difference between normal and hyperacusis people in all frequencies except for 0.5 kHz (1.37~5.83 dB HL; p ≤ 0.05). Using both self-reported symptoms and LDL is more useful to assess hyperacusis
Huang et al. (2023)	Randomized controlled	-47 normal	-Less than 20 years: 5; 20~30 years: 24; 40~50 years: 18	-37 F and 10 M	0.25, 0.5, 1, 2, 4, and 8 kHz	Pure tone

F: female, M: male, TRT: tinnitus retraining therapy, LDL: loudness discomfort level, HL: hearing loss, ULL: uncomfortable loudness level, HQ: hyperacusis questionnaire, ROC: receiver operating characteristic, NRS: numeric rating scale, PSD: power spectral density, ERSP: event-related spectral perturbation, WBN: white band noise

Table 4.

Comparison of the extracted and synthesized data for loudness discomfort levels (mean and standard deviation in dB HL) as the testing frequency in normal hearing listeners and patients with hyperacusis drawn from the studies

Group	Authors (year)		Subject (n)	Age (yr)	Frequency (kHz)
Group	Authors (year)		Subject (n)	Age (yr)	0.125	0.25	0.5	1	2	3	4	6	8	All (average)
Normal sensitivity	1A	Diehl & Schaette (2015)	13				109.04 (2.14)	106.43 (1.97)	108.71 (2.31)		109.44 (2.31)
	2A	Sheldrake et al. (2015)	59	28			102.20 (11.80)	103.90 (10.70)	101.70 (12.00)		100.90 (13.60)
	3	Knudson & Melcher (2016)	29	34~63										109.55 (2.56) (0.5 kHz)
	4A	Enzler et al. (2021)	54	33 ± 15.0			101.89 (11.35)				87.36 (11.48)		82.66 (13.36)
	5A	Erinc& Derinsu (2022)	20	39.8 ± 11.8			105.37 (3.46)	107.12 (4.06)	106.5 (3.61)		106.87 (4.03)		103.12 (3.70)
	6A	Vidal et al. (2022)	20	31.6 ± 9.3										93.90 (9.52) (0.125, 0.25, 0.5, 1, 2, 4, 6, and 8 kHz)
	7A	Huang et al. (2023)	40	-20: 5		102.18 (6.37)	110.74 (11.07)	114.26 (12.00)	113.83 (12.69)		111.65 (12.10)		105.90 (8.10)
				-21~40: 24
				-41~60: 18
				-61~80: 0
Hyperacusis	8	Hawley et al. (2007)	68	56 (15-75)				88.10 (14.4)	87.00 (14.7)		88.10 (18.0)		91.90 (18.7)
	9	Jüris et al. (2013)	62	40.2 ± 12.2		73.66 (0.00)	75.32 (11.35)	73.94 (11.62)	72.65 (10.46)	70.20 (11.27)	69.72 (12.78)
	1B	Diehl & Schaette (2015)	130		83.94 (2.39)	91.99 (2.65)	92.85 (2.56)	91.99 (2.82)	90.45 (2.56)		89.25 (2.48)	89.94 (2.74)	78.80 (3.08)
	2B	Sheldrake et al. (2015)	381	43.9 ± 15.0	77.00 (14.93)	83.40 (15.54)	85.40 (15.54)	85.10 (15.16)	83.70 (15.99)		84.00 (17.95)	85.40 (18.85)	78.00 (18.70)
	10	Silverstein et al. (2016)	6	67.0 ±9.0										73.67 (6.33) (0.25, 0.5, 1, 2, 4, and 8 kHz)
	11	Aazh & Moore (2017)	573	55.0 ±17.0		83.05 (14.45)	84.55 (14.65)	84.90 (14.15)	84.49 (15.10)	86.20 (14.85)	85.85 (15.75)	86.40 (16.20)	82.35 (18.25)
	12	Aazh et al. (2018)	62	12.0 ±4.1		69.00 (15.00)	68.50 (15.50)	70.50 (13.50)	66.50 (16.50)	68.00 (19.50)	67.50 (17.00)	62.00 (22.00)	60.00 (19.50)
	13	Aazh et al. (2021)	100	55.0 ±13.0		78.00 (10.00)	79.00 (10.50)	79.50 (10.00)	79.00 (11.00)	79.00 (11.00)	79.00 (11.50)	79.00 (12.00)	75.50 (14.00)
	4B	Enzler et al. (2021)	27	41 ±15.0			81.60 (12.58)				69.86 (11.13)		65.08 (13.44)
	5B	Erinc & Derinsu (2022)	20	38.7 ±14.6			88.00 (9.92)	87.62 (9.05)	86.87 (11.30)		86.62 (11.89)		81.37 (13.53)
	14	Shin et al. (2022)	51	46.9 ±14.5										80.83 (19.13) (0.25, 0.5, 1, 2, 4, and 8 kHz)
	6B	Vidal et al. (2022)	21	47.9 ±11										74.00 (2.96) (0.125, 0.25, 0.5, 1, 2, 4, 6, and 8 kHz)
	7B	Huang et al. (2023)	47	-20: 5		100.08 (7.16)	109.37 (11.38)	110.32 (13.01)	109.21 (12.99)		106.83 (14.57)		99.76 (12.23)
				-21~40: 16
				-41~60: 15
				-61~80: 4

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