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|Year : 2009 | Volume
| Issue : 44 | Page : 156--160
Could an underlying hearing loss be a significant factor in the handicap caused by tinnitus?
S. A. B. Ratnayake1, V Jayarajan1, J Bartlett2,
1 Department of Audiological Medicine, Royal Surrey County Hospital, Guildford, United Kingdom
2 Department of Audiology, Royal Surrey County Hospital, Guildford, United Kingdom
Department of Audiological Medicine, Royal Surrey County Hospital, Egerton Road, Guildford, Surrey GU2 7XX
There have been several studies that have demonstrated a link between the hearing loss of subjects and tinnitus. However, there has been no systematic evaluation of the link between perceived tinnitus distress and an underlying hearing loss. The purpose of the current study is to explore this association, and ascertain whether a subject's hearing loss contributes to the handicap caused by tinnitus. A group of 96 adults were evaluated with Pure Tone Audiometry and a questionnaire that included the Tinnitus Handicap Inventory (THI). In 58% of the subjects, the side of the unilateral or worse tinnitus corresponded with the ear with poorer hearing thresholds. A subset of the THI, the Two Question Mean (TQM) that was related to questions with regard to communication, correlated significantly with the hearing thresholds in the better hearing ear ( P < 0.01). There was also a significant correlation between the THI and TQM scores ( P < 0.01). These results suggested that in tinnitus subjects with impaired hearing, the underlying hearing loss may be a significant factor in the perceived distress.
|How to cite this article:|
Ratnayake S, Jayarajan V, Bartlett J. Could an underlying hearing loss be a significant factor in the handicap caused by tinnitus?.Noise Health 2009;11:156-160
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Ratnayake S, Jayarajan V, Bartlett J. Could an underlying hearing loss be a significant factor in the handicap caused by tinnitus?. Noise Health [serial online] 2009 [cited 2021 Apr 17 ];11:156-160
Available from: https://www.noiseandhealth.org/text.asp?2009/11/44/156/53362
The distress and handicap caused by tinnitus are often quite difficult to assess. This is because tinnitus is subjective and often tends to fluctuate. The perception of tinnitus also tends to be influenced by the subject's mood and surroundings. Tools that have been used to assess the severity of tinnitus include structured interviews, , diaries, visual analog scales,  and tinnitus-specific questionnaires.
Several tinnitus questionnaires are currently used in Tinnitus Clinics. One of the earliest was the 'Tinnitus Questionnaire.'  Two other questionnaires on tinnitus are now widely used in research studies - the Tinnitus Reaction Questionnaire  and the Tinnitus Handicap Inventory (THI).  Both these questionnaires have a high correlation with the distress caused by tinnitus. In addition, the THI has been widely used both clinically and in studies aimed at evaluating the outcomes of tinnitus treatment.
The correlation between tinnitus and an underlying hearing impairment has been studied by several authors. Thus, Davis  found that there was a close link between the degree of hearing loss and tinnitus in the general population, while Coles et al.  noted the high prevalence of tinnitus in subjects with cochlear disorders. In his neurophysiological model of tinnitus, Jastreboff  postulated that cochlear dysfunction was significant in the generation of tinnitus. Chung et al.  in a study of 30,000 workers exposed to high noise levels noted that the prevalence of tinnitus in this group increased significantly with increasing age and increasing hearing loss.
It could be assumed therefore that in a cohort of patients with troublesome tinnitus there would be a significant proportion of subjects with impaired hearing. Many of these patients might feel that the tinnitus, rather than the underlying hearing loss was responsible for their hearing difficulties.
This subject has not been analyzed in detail. We were able to find only a single study that explored the link between the handicap caused by tinnitus and an underlying hearing loss  However, these authors did not carry out a statistical analysis of their results.
It is important for clinicians to be aware of the exact cause of a patient's disability. Appropriate treatment measures can only be carried out when this information is available. It is therefore felt that the association between the distress caused by tinnitus and any underlying hearing loss should be carefully evaluated in order to establish a better understanding of the nature of such distress. This is the aim of the current study.
Materials and Methods
The study was carried out prospectively at the Royal Surrey County Hospital, Guildford, UK, after obtaining approval from the South West Surrey Local Research Ethics Committee. Data was collected over a total duration of 16 months in two stages (November 2002-November 2003 and November 2006-January 2007). As the number of subjects in the original cohort (November 2002-November 2003) was insufficient the study was extended to the second stage (November 2006-January 2007). There was no change in the protocol during the second stage.
All the subjects were first time attendees at the Audiology Clinic. They were recruited consecutively during the study period. Patients of both sexes, over the age of 17 years, were invited to participate. The criterion for inclusion was that the patient should have been referred specifically for the treatment of tinnitus.
Suitable subjects were given an information leaflet that explained the protocol used in the study. If they expressed a willingness to participate, they were asked to complete a questionnaire [Appendix]. This included;
Questions about the duration and laterality of the tinnitusThe 25 questions of the THI
Information was sought about the side of the tinnitus (laterality). If the tinnitus was unilateral, the subjects were asked to state this (i.e., right or left). In case of bilateral tinnitus, they were requested to state 'right' or 'left' if the tinnitus was more intrusive on one side. However, if the tinnitus was perceived equally in both ears, it was designated 'bilateral'.
The questionnaires were given to the patients by only two of the authors (SABR and VJ). They gave an explanation to each patient about completing the questionnaire. This was done in order to reduce bias, as neither of these authors was aware of the results of the Pure Tone Audiogram when they handed the questionnaires to the patients.
Two questions in the THI were related to problems with communication (question 2 and question 9). It was considered that these may be linked to an underlying hearing loss rather than tinnitus. A separate analysis was therefore carried out on the total score of questions 2 and 9. Two-Question Mean (TQM) was the mean score of the responses to questions 2 and 9. The total THI and TQM scores ranged from 0 to 100 and 0 to 8, respectively.
Pure Tone Audiometry (PTA) was performed on all subjects by one of the authors (JB) using a GSI 61 Audiometer in a sound proof audiology booth. The audiometer was calibrated in July 2002, July 2003, and June 2006. Air conduction thresholds were measured in both ears, in the following frequencies: 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, and 8 kHz. The Mean Hearing Threshold (MHT) was the arithmetic mean of air conduction thresholds at the above frequencies. This was calculated for all subjects in each ear.
The statistical package used was SPSS version 14 software for Windows. The results were analyzed using the Pearson Correlation Test and the Phi Coefficient.
A total of 102 patients were recruited in the study. Six patients were excluded due to insufficient data, or incorrectly completed questionnaires, resulting in a final cohort of 96 subjects.
There were 45 males and 51 females in the study population. The mean age of the subjects was 60.1 years. The mean tinnitus duration was 6.3 years [Table 1].
Analysis of tinnitus laterality
A further analysis was carried out to ascertain whether there was a correlation between the laterality of the tinnitus (right, left or bilateral) and the ear with worse hearing [Table 2]. The results showed that in 53 of the 91 subjects (58%) in the cohort, the side of the unilateral or 'worse' tinnitus corresponded with the ear with poorer hearing thresholds. This was statistically significant (Phi Coefficient = 0.56, P Analysis of THI and TQM scores
The THI score for all subjects ranged from 0 to 88 with a mean of 31.8 (standard deviation + 20.0). The TQM for all subjects ranged from 0 to 8 (mean = 3.2, standard deviation + 2.5) [Table 3].
The Pearson Correlation (r) was used to assess whether there was an association between each THI score and TQM score and the better ear hearing thresholds. The results showed that the TQM correlated significantly with the hearing threshold of the better ear (r = 0.37, P P = 0.47).
A Pearson Correlation Analysis was carried out on the THI and TQM scores of the entire cohort. The results showed a significant correlation between these two scores ( P 
The World Health Organization (WHO) issued revised guidelines with regard to the terms 'Impairment', 'Disability,' and 'Handicap', as a result of a meta-analysis of publications relating to these terms. The article described 'Impairment' as 'any temporary or permanent loss or abnormality of a body structure or function', while 'Disability' was perceived as 'a restriction or inability to perform an activity in the manner or within the range considered normal for the individual'. The term 'Handicap' was described as the result of an impairment or disability that limited or prevented the fulfillment of one or several roles regarded as normal. 
It can be readily seen that both hearing loss and tinnitus are 'Impairments', resulting from a loss or abnormality of function of the cochlea, the vestibulocochlear nerve or the central auditory pathways. Both these symptoms tend to cause a restriction of normal activity. Thus, while a hearing loss may restrict an individual's ability to hear speech, tinnitus could affect his or her concentration. Hence, these subjects may find it difficult to participate in meetings and conferences. These disabilities could also have an impact on a person's social life, preventing enjoyment of activities such as, listening to music and watching the TV. The resulting handicap may be quite severe.
This topic has been extensively studied by other authors. ,, The range of disabilities mentioned in these articles was in broad agreement with the proposed list in the WHO document. It is therefore apparent that both tinnitus and an impairment of hearing can cause a significant disability, resulting in a handicap. This could have a detrimental effect on a subject's quality of life.
In a large multicenter study carried out in the UK, Davis  showed that 16% of the adults (17-80 years) had a > 25 dB HL hearing impairment in both ears. The author also showed that overall, 26% of the adults reported great difficulty with hearing speech in noise. Furthermore, the study showed that approximately 10% of the adults experienced 'prolonged spontaneous tinnitus' (i.e., tinnitus that lasted more than five minutes at a time). It could therefore be assumed that a large proportion of subjects who reported difficulties with their hearing may also have significant tinnitus.
Several authors have attempted to evaluate the potential link between tinnitus distress and an underlying hearing loss. ,,, Newman et al.  studied a cohort of 67 adults with tinnitus. They reported that there were no significant differences in the THI scores for those with normal hearing (speech frequency and pure tone averages of 20 dB or less in both ears) and those with hearing losses. In a study of Greek patients with tinnitus, Vallianatou et al .  showed that in a group of 80 tinnitus patients, the percentage of hearing loss was not an important factor with regard to the subjects' assessment of tinnitus intensity. Holgers et al .  carried out an analysis of the risk factors that could predict the probability of 'absence from work related to tinnitus'. They found that in a cohort of 79 adults with tinnitus, the pure tone average of 0.5, 1, and 2 kHz in both ears correlated significantly with the severity of the tinnitus. Zaugg et al.  studied a group of 170 military veterans with tinnitus. In this cohort only three subjects were found to have normal hearing and 89.5% answered "yes" or "sometimes" to the question "Does the loudness of your tinnitus make it difficult to hear people?" These authors were of the opinion that many individuals attributed their hearing loss to tinnitus. Failure of the patients to acknowledge their hearing loss as a primary condition may be the reason that their tinnitus continues to be a problem for them.
The two questions of the THI that were evaluated separately (questions 2 and 9) do not constitute a validated measure of hearing disability. However, they do relate to specific difficulties that would be experienced by subjects with impaired hearing, although, the wording of the questions implies that these problems were caused by the subject's tinnitus. It is our view that positive responses ('yes' or 'sometimes') to questions 2 and 9 should be interpreted as an indication of a hearing disability. This was the basis of the separate analysis carried out on these questions.
In the present study there was no significant correlation between the hearing thresholds in the better ear and the total THI score (P = 0. 47). However, we found that the TQM values were closely linked to the mean hearing thresholds in the better ear ( P P et al.  A possible reason for this finding is a reduction of the ability of the ear with worse hearing to hear ambient noise. The perception of tinnitus would therefore be greater on this side, because the retraining of the higher processing centers leading to a 'gradual reorganization of the recognition of tinnitus,' as postulated by Jastreboff,  is deficient.
The study provides evidence that shows a link between the distress caused by tinnitus and the subjects' perceived hearing disability. This disability is in turn linked to the underlying hearing loss. The results led us to conclude that -
In tinnitus subjects, the awareness of impaired hearing may in fact be due to an underlying hearing loss rather than their tinnitus.In these cases, the impairment of hearing may contribute significantly to the perceived distress caused by the tinnitus.
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