1 OCCUPATIONAL HEARING IMPAIRMENT 2 SOUND DEFINITIONS •Sound consists of physical pressure fluctuations that are characterised by amplitude,frequency and time pattern • •Frequency-the rate at which the pressure fluctuations repeats in a sinusoidal curve • •The range of human hearing is : •20Hz-20 000Hz • Classes of Noise •-Continuous noise: is produced by high velocity air flow in compressors,fans,gas burners,and motors. Crushing,drilling,and grinding are important sources of continuous noise. •- Impact noise: results from sharp or explosive inputs of energy into some object or process,such as hammering or pounding on metal,dropping heavy objects. 3 • •In many industrial situations impulsive noice components are superimposed on a backround of continuous noice. 4 Attention: 5 • •Acustic trauma •Temporary treshold shift (TTS) •Permanent treshold shift (PTS) Categories of Hearing Loss Classification of Noice-Induced Hearing Loss (NIHL) •A. Auditory Health Effects •B. Non-auditory Health Effects 6 7 –Onset of hearing loss is instanteous –May also suffer from tympanic membrane perforation(s),or disarticulate the ossicles –Followed by immediate pain, a tickling sensation,vertigo,tinnitus,reduced communication skills… –Caused by blasts or explosions Acustic trauma 8 Level of the Noise in the Environment Level of the sound dB Effects Source 140 Acustic trauma Aircraft engine 130 Level of the pain stamping 120 Extremely strong noise Strart of the military airforce airplane 110 Very strong noise bigbeat 90 Strong noise –health risk Tram, track,mixer 70 Lower level of noise Classroom, TV 50 Light sound Pedestrian in the night 40 silence clock 20 Deep silence Snow forest 10 Hearing level 9 Noise in the Workplace •The most common risk factor among hazardous workplace exposures. • • •airports, construction sites, heavy machinery, service of the compressor stations •stamping, pressing •wood industry, textile industry (operators, •service of the vehicles and construction machines, miners, … 10 •A)Specific-auditive •Effect on ear leads to temporary or permanent impairment • •B)Non-specific- extraauditive • blood hypertension, sleeping disturbances, mood disturbances, neurosis, … stress reaction •….. •ss Health Effects of Noise 11 • •Methods of the detection of hearing defects •Speach audiometry-provides essential diagnostic information •Tympanometry- used to assess the function of the conductive auditory mechanism. Sensitive technique. •Audiometry (pure-tone audiometry) •Tunning fork test • • • • Examination of the hearing Hearing Impairment •1.Conductive Deafness • •2.Sensorineural Deafness • •3.Combination 12 13 •acute •Explosion trauma of the ear •Acustic trauma of the ear gr. I.–III. • •chronic •hypacusis perceptiva bilateralis profess. • •Ototoxic substances in the workplace: •As,Co,Pb,Hg,Li,cyanide,benzene,carbon disulfide,aniline,industrial solvents Occupational Hearing Loss 14 Acute explosion trauma •From the sudden press difference in the middle ear and in sourounding environment •Mechanical • •Damage of the ear drum, middle ear and inner ear (labyrinth) • •pain, hemorrhage the middle ear , hearing impairment in the wide frekv. zone , titubatio • • • • mixed hearing loss • conductive-perception bilat. Tblast 15 Acute acustic trauma •Outcome of one sudden noice impulse • •missing protective mechanism of the ear, sudden change of the preassure makes mechanical damage of the sensor. cells in the inner ear, eardrum, middle ear bones • •Painful preasure in the ear, tympanophony,tinnitus, temporary hearing loss (4 kHz) •In case of recurence permanent hearing loss • • perceptive type of hearing loss • unilat. (one ear) tlumic 16 Chronic hearing impairment •bilateral permanent hypacusis induced by long term exposition of the excessive noice • • •Loss of sensory cells – irreversible changes • •hypacusis= partial hearing loss, which often costs problems in communication • 17 audiometrie-s MA53_120 IMG_0856 Audiometric Examination Procedures 18 audio 2 AUDIOGRAM 19 20 Characteristic •Permanent irreversible hear impairment (manifested on „ speach frequenties“) • •Treatment is not efficient • •Combination of the noise exposure in working and communal environment and (senile) presbyacusis • Evidence of Hearing Loss •Early signes of hearing loss include: •1.Difficulty in understanding spoken words in a noisy environment •2.Need to be near or look at the person speaking to help understand words •3.complaints that people do not speak clearly •4.Ringing noises in the ear • 21 22 Hearing Loss as Occupational Disease • • • noice-induced hearing loss – total hearing loss 40- 50% according – the age (methodology by Fowler) • •Condition of origin occupational disease • disease starts during the work with proved excessive exposition to the noise = over 85 dB/shift, impulsive noise exceeded 140 dB in the peak 23 Audiogram •A graf showing hearing (treshold)level as a function of freqency, •Result of AUDIOMETRY- measurment of hearing • •Hearing level: number of decibels that the subjects treashold of hearing lies above the zero reference for that frequency. • •Noice-induced hearing loss (NIHL) is first detected on pure tone audiometry, measured at 250,500,1000,2000,3000,4000,8000Hz •Tresholds in hearing are expressed in decibels (dB) •Normal range at each frequency 0-20dB •Evaluation // •Mild: NHILwith losses 20-40 dB •Moderate: 40-60 dB •Severe: 60-80 dB •Profound: more than 80 dB • • 24 25 Assesment of Proffessional Hearing Loss •As occupational disease is considered and proved hearing impairment caused by noise leading to binaural hearing loss according Fowler: • • patient up to 30 years old - more than 40% • patient over 50 years old - more than 50% • patient 30-50 years - limit 40% plus • 0,5% for each year of age • •Hygienic examination at the workplace proves,that the condition for origin of occupational disease had been fulfilled 26 Prevention • •Technical- modification of the work procedures creating noise • •Organizational – removal of the worker from a noisy environment ,regular breaks • •Use of Personal Protective Equipment-earmuffs, earplugs • •Employment Preplacement Examination, Periodic Health Examinations 640_0 27 • Thank you for your attention