The characteristics of tinnitus in workers exposed to noise

Braz J Otorhinolaryngol 2009;75(1):7-14. original article The characteristics of tinnitus in workers exposed to noise Luciara Giacobe Steinmetz1, Bianca Simone Zeigelboim2, Adriana Bender Lacerda3, Thais Catalani Morata4, Jair Mendes Marques5 Keywords: hearing loss, prevention, occupational noise. Summary T innitus is a common auditory complaint among individuals exposed to noise. Aim: this paper aims to study the characteristics of tinnitus in workers exposed to noise. Study design: this is a descriptive prospective study. Materials and method: Fifty-two individuals averaging 29 years of age were enrolled in a hearing loss prevention program at a meat processing plant. The participants were interviewed and had their hearing tested in 2005 and 2006. Results: seventy-one percent of the participants were found to have normal hearing. Tinnitus was present in 16% of the males and in 9% of the females. Mean noise exposure length was 7 years and noise levels ranged from 86 to 91 dBA (48%). Bilateral tinnitus (46%) of the hissing type (40%) and moderate intensity (49%) was the most prevalent. Symptoms began to be observed within one to five years after initial exposure to noise (67%) and manifested themselves in weekly episodes (41%) that bothered the patients mostly at night (34%). A significant correlation was observed between the frequency of tinnitus episodes and the noise levels to which workers were exposed. Conclusion: tinnitus should be included in hearing loss prevention programs in order to more comprehensively promote occupational hearing health. 1 MSc on Communication Disorders at Universidade Tuiuti do Paraná, clinical speech and hearing therapist. PhD, Coordinator of the Masters and Doctoral Program on Communication Disorders at Universidade Tuiuti do Paraná. 3 MSc on Communication Disorders at Universidade Tuiuti do Paraná, Professor at the undergraduate and specialization program on Clinical Audiology at Universidade Tuiuti do Paraná. 4 Post-Doctorate at NIOSH - Professor - Communication Disorders Graduate Program - Universidade Tuiuti do Paraná and Researcher at the National Institute for Occupational Safety and Health, EUA 5 PhD on Geodesic Sciences at Universidade Federal do Paraná, Professor at the Masters and Doctoral Program on Communication Disorders at Universidade Tuiuti do Paraná. Institution: Universidade Tuiuti do Paraná. All authors have their curricula registered under the CNPq. Send correspondence to: Dra. Bianca Simone Zeigelboim - Rua Gutemberg 99, 9º andar Curitiba PR 80420-030. Tel/Fax: (0xx41) 3331-7807 - E-mail: This paper was submitted to the RBORL-SGP (Publishing Manager System) on 14 May 2007. Code 4516. The article was accepted on 14 July 2007. 2 Brazilian Journal of Otorhinolaryngology 75 (1) January/February 2009 http://www.rborl.org.br / e-mail: 7 INTRODUCTION from the Ministry of Labor12 as described below. a) Participants were interviewed and demographic, medical history and labor history data were collected, along with tinnitus-related facts. b) Participants had their acoustic meatuses inspected for earwax. c) Threshold tone audiometry tests were carried out in a soundproof booth after participants had acoustically rested for 14 hours. We used an AD 229 Interacoustics audiometer with TDH-39 earphones calibrated in accordance with international standards (ISO 8253) to perform the tests. Air conduction audiometry was done for frequencies ranging from 250 Hz to 8 kHz, and when the threshold was above 25 dB the analysis was carried out via bone conduction audiometry using frequencies from 500 Hz to 4 kHz. Audiometry tests were ranked in accordance with Ordinance 19 from the Ministry of Labor12. This ordinance covers preventive measures and states that the acceptable limits are those in which the audiograms show hearing thresholds equal to or lower than 25 dB (HL), for all examined frequencies. Findings of upper hearing thresholds above 25 dB (HL) at frequencies of 3 kHz and/or 4 kHz and/or 6 kHz in both air and bone conduction audiometry are indicative of noise-induced hearing loss (NIHL) in one or both sides. Audiograms not meeting the above mentioned criteria are not suggestive of NIHL. Participants were then asked to answer the Brazilian Portuguese translated and adapted version of the Tinnitus Handicap Inventory (THI) questionnaire designed by Newman et al13. The THI consists of 25 questions grouped into three subcategories with three options to choose from for each question. Scores are assigned to the answers as follows: each ’yes’ is worth four points; each ’sometimes’ is worth two points; ’no’ answers are not given points. All points are then added together to assess tinnitus severity for each individual. Studies14-15 suggest that the outcomes be divided into five degrees of severity, namely: Grade 1 - negligible tinnitus; Grade 2 - mild tinnitus; Grade 3 -moderate tinnitus; Grade 4 - severe tinnitus; and Grade 5 - catastrophic tinnitus. According to the literature16, tinnitus severity can be assessed the following way: Grade 1 tinnitus is only perceived in quiet environments; Grade 2 can be easily masked by background noise and easily forgotten when the subject is busy; Grade 3 tinnitus is heard in the presence of background noise and everyday tasks can still be performed in spite of it; Grade 4 tinnitus is almost always present, the subject’s sleep is disturbed and his or her daily life may be compromised: Grade 5 tinnitus is heard all the time, the subject’s sleep is altered, and some daily tasks may become difficult to perform. Research indicates that approximately 17% of the population in general and 33% of the elderly population is troubled by tinnitus. It develops into its severe manifestation in 20% of the cases, leading to significant suffering in 4% of the population in general. Tinnitus may directly or indirectly impact individuals during labor and leisure, interfering in family and social relations, and in extreme cases resulting in suicide1-4. In Brazil, it is estimated that approximately 6 million people are affected by tinnitus. In spite of the many theories around the likely causes, there is no scientific proof due to the lack of objective, non-invasive methods to detect the condition and locate the associated neural activity5. Tinnitus, regardless of hearing complaints, is an auditory symptom widely reported by individuals exposed to high sound pressure levels (SPL)6-9. Studies have mentioned7 that prolonged exposure to occupational noise can not only lead to hearing loss, but also to tinnitus and hypoacusis. Excessive exposure to noise is the most important risk factor for hearing loss and tinnitus, followed by age and gender10. Authors11 have described duration of exposure and noise severity as reported by workers exposed to high SPL as significantly associated with tinnitus. This study aims to study the characteristics of tinnitus reported by individuals exposed to occupational noise. M (...truncated)