INTRODUCTION There is a strong correlation between tinnitus and hearing loss (1), and the buzz is found in 65% of sensorineural hearing loss, mixed losses of 5% and 4% of conductive hearing loss, but there are data showing the presence of tinnitus also individuals with normal hearing (2). In the latter case, the isolated presence of tinnitus can be the first symptom of a pathology that is only diagnosed after the onset of hearing loss.
Tinnitus is characterized as a disease but as a symptom, however, affects thousands of people worldwide (3).
The speech recognition is one of the most important measurable aspects of human auditory function (4). Tinnitus affect the quality of life, causing impairment in communication (5).
For a complete audiological diagnosis is essential to carry out measures of speech recognition (4). Percentage Index of Speech Recognition (IPRF) aims to measure the intelligibility of speech, being held in a fixed intensity and comfortable for the patient, which should be repeated as many monosyllabic words correctly (6.7). By analysis of the SD, one can observe the degree of difficulty understanding speech. It is considered the result as expected, when the percentage is 88 to 100% accuracy, with the intensity shown at 40 dB above the average three-tone (500, 1000 and 2000 Hz) (6).
The presence of tinnitus and low IPRF can produce significant changes in the individual's communication and consequently the quality of life. The aim of this study is to investigate possible changes in SD from individuals with tinnitus have normal hearing and examining the relationship between tinnitus, gender and age.
METHOD We performed an exploratory research, to approach the problem quantitatively, covering activities and bibliographical analysis 480 audiological assessment database of the Audiology Clinic of the University Hospital of Santa Maria (HUSM) assisted in the years 2005, 2006, 2007 and January-August 2008.
Inclusion criteria for this study were: to present normal audiological evaluation, presence or absence of tinnitus complaints referred to the audiological history and integrity of tympanic-ossicular system checked by tympanometry (type A tympanogram curve and acoustic reflexes present). Was considered normal audiological evaluation showed that the hearing thresholds equal to or less than 25 dB at frequencies from 250 to 8000 Hz (8).
The audiological evaluation consisted of:
Tone audiometry (PTA);
Speech audiometry (Speech Reception Threshold - LRF and Percentage Index of Speech Recognition - SRI);
Immittance (tympanometry and acoustic reflexes).
Percentage Index of Speech Recognition (SRI) is a measure of speech intelligibility in a fixed intensity at which the individual can correctly repeat as many words. It uses a list of 50 monosyllabic words, 25 words are presented to each ear at an intensity of 40 dBSL. It is expected that individuals with normal hearing have between 92 to 100%, ie, the individual may submit up to two errors (7).
Of the 480 hearing assessments analyzed, only 82 were in accordance with the criteria for inclusion. These evaluations were divided into the Control Group (CG), composed of individuals without tinnitus and Study Group (SG), composed of individuals with tinnitus, but in this study were analyzed separately in the ears of the above criteria. The two groups were composed of individuals of both sexes.
The sample age ranged from 21 to 70 years of age. Patients were classified into five age groups:
Track 1: from 21 to 30 years;
Track 2: 31 to 40 years;
Track 3: from 41 to 50 years;
Track 4: 51 to 60 years;
Track 5: from 61 to 70 years.
Were statistically analyzed gender or tinnitus, tinnitus and age, as well as the influence of tinnitus in IPRF Study Group.
For statistical analysis, this study classified the results of the SD as IPRF without influence, as the rate obtained was 100% correct answers and how to influence IPRF, when the value was 92 and 96%. These criteria were adopted, since the study was composed only of normal hearing subjects, namely, that IPRF showed above 88%. The percentage of less than 88% accuracy is found in individuals with sensorineural hearing loss (7).
The groups were statistically analyzed through nonparametric tests and chi-square test of difference between two proportions, and the significant value of 0.05 (5%), which is statistically significant when the value calculated significance (p) is lower than the level of significance.
This study is linked to the Project "Research and data base on hearing health," being duly registered with the Ethics Committee under number 0138.0.243.246-06.
RESULTS By inclusion criteria, 82 individuals were selected, totaling 128 ears with normal hearing. For this study were analyzed separately for each ear within the criteria for inclusion, for each ear is behaving statistically independent.
The control group (CG) comprised 56 ears of patients aged between 22 and 66 years, 42 females and 14 males.
The study group (SG) consisted of 72 ears of patients aged 21 to 70 years, 40 ears were female and 32 male.
Of the 480 records, 17.08% had normal hearing and 7.5% complained of tinnitus, and both analyzed in this study.
The prevalence of female gender in both groups, with percentage of 56% in the study group and 75% in the control group (Graphic 1). With respect to gender and the presence or absence of tinnitus, significant difference was found, using the chi-square test (p = 0.023). This difference found is due to the high number of females in the control group.
We used the chi-square test to compare the gender variable with IPRF IPRF without influence and with influence, but there was no significant difference (p = 0.787), however, note that there was a greater number of IPRF with influence in female (Table 1).
Among subjects of the SG (with complaints of tinnitus), we observed that the age group 31 to 40 years (range 2) showed a higher incidence of tinnitus (41.67%) (Graphic 2), however, the mean age individuals with no influence IPRF (41.43 years) and influence with IPRF (41.57 years) is aged 41 to 50 years (range 3).
Comparing the age of the sample, it was observed that the age group less than complained of tinnitus was 41 to 50 years (range 3), 18.75%. What had more complaints of tinnitus, was the second track (31-40 years) with 23.44%, in agreement with the previous graphic (Graphic 2). The age group 5 (61-70 years) showed the lowest number of ears in both groups (Graphic 3 ).
Analyzing the variables tinnitus and IPRF in both groups, there was no statistically significant difference when applied the chi-square (P = 0.20). However, it was found that there is a higher percentage of IPRF with influence in patients with tinnitus (61.11%) compared to non-carriers (50%). Comparing further the influence of IPRF with both groups, by testing for difference between two proportions (p = 0.21) was not statistically significant difference (Graphic 4).
Graphic 1. Individuals distributed as to gender.
Graphic 2. Sample of tinnitus patients distributed as the variable age.
According to the National Institute of Health, tinnitus is a very common symptom, affecting approximately 15% of Americans (9). One study (10) on the prevalence of tinnitus in a random sample of a Brazilian capital, said 25% of respondents had such a complaint, regardless of audiometric configuration presented. However, this study, only individuals with normal hearing, 7.5% of subjects treated in the period studied, with complaints of tinnitus. This finding agrees with the literature, which reports (1, 11) very close to this percentage (7.4% and 8-10%).
Females predominated in both groups (Graphic 1), with no significant differences between groups. These findings corroborate other studies (1) similar, in which the proportion of women was also higher in both groups (67.3% in the study group and 55.6% in control group), but no significant difference between groups.
The study covered a wide age range (21 to 66 years). For some authors (12) tinnitus can affect all age groups. The age group with the highest number of individuals with tinnitus was 31 to 40 years (41.67%). Result similar to that found in the literature (13), which states a greater number of individuals aged below 40 years (46.6%).
Some research (1.14) say that the buzz appears after age 40 and another study reported an average age of the group with tinnitus of 45.62 years (14). Contradicting these studies found that people aged 41 to 50 years (age 3) had fewer complaints of tinnitus.
Regarding age, we found few individuals in the range of 61 to 70 years in both groups. It is believed that this small number of individuals due to the high incidence of hearing loss in this age group, which is not included in the objectives of this study. There is prevalence of hearing loss in elderly patients, usually with an average age of 65 years (2). Literature (15) still shows an increase of tinnitus with increasing age.
About 95% of the normal population has experienced tinnitus, but it is considered important when it becomes continuous and troublesome (16). Cases of tinnitus in normal hearing individuals constitute a significant sample, because their characteristics can be attributed to tinnitus, and not to hearing loss (17). In these cases the impact is greater, causing anxiety, irritation, tension, insomnia, and sometimes even depression (18,19).
The patient suffering from tinnitus should always be subjected to medical assessment for diagnosis and treatment of possible underlying pathology (20). It is believed that the individuals affected, a loss occurs the modulation of outer hair cells with normal inner hair cells, generating an abnormal activity in the auditory pathways, erroneously interpreted as sound. The outer hair cells more susceptible to injury are those located in the most basal region of the cochlea. Another hypothesis for the occurrence of tinnitus in individuals without hearing loss, could be explained by diffuse damage of up to 30% of outer hair cells throughout the cochlear spiral, with no impairment of the auditory threshold (3).
In view of this and considering that the buzz is in most cases, a debilitating problem (21) may lead to the bearer of a suicide attempt (22), emphasizes the importance of research on tinnitus.
Its cause is still unclear, but there are many hypotheses. It can be a symptom of some diseases, such as ear, metabolic, psychiatric, dental, trauma, cardiovascular, neoplastic, neurological and pharmacological (9, 23,24).
It is known that tinnitus is a disorder that produces discomfort in social life, work performance and even family relationships (25). In most cases, can become intolerable, going to interfere with sleep, concentration and emotional balance (26).
A greater number of IPRF with influence in females, probably due to gender in prevalence since the two groups. The average age of individuals with influence IPRF found himself at the age of 41 to 50 years (range 3). One possible explanation for this deterioration in speech recognition, especially in this age group, would be the beginning of the aging effect, beyond the influence of tinnitus. One study (27) on aging and speech recognition in normal hearing subjects, the analysis of the thresholds of sentences in quiet and in noise, found that speech recognition of individuals over 50 years was significantly lower than those of adults.
No studies were found relating tinnitus and speech tests. In this study, no significant relationship was found between the presence of tinnitus and the decrease of the SD in patients with normal hearing.
There are reports in the literature (28) correlating tinnitus and difficulty understanding speech in individuals with complaints of hearing loss, and there are few studies in normal hearing subjects.
Graphic 3. Age group x number of patients.
Graphic 4. Percentage of patients x IPRF.
It was concluded that the presence of tinnitus does not interfere with speech intelligibility, analyzed using the IPRF, and there is no relationship between tinnitus and age. A relationship was found between tinnitus and the female gender.
Due to the results found in this study and found little literature, we suggest further studies with larger samples on this subject.
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1 Graduate student in Human Communication Disorders, Universidade Federal de Santa Maria (UFSM), Santa Maria / RS, Brazil. Speech Therapist.
2 PhD Professor, School of Speech, Federal University of Santa Maria (UFSM), Santa Maria / RS, Brazil.
Institution: Universidade Federal de Santa Maria. Santa Maria / RS - Brazil. Mail Adress: Daila Urnau - Rua Vale Machado, 1605 - Apto. 405 - Centro - Santa Maria / RS - Brazil - Zip code: 97010-530 - Telephone: (+55 55) 3028-4070 / (+55 54) 9135-5594 - E-mail: daila_urnau@yahoo.com.br
Article received on August 2, 2010. Approved on 1 September 2010.
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