The G 20 precautionary examination is used for the early detection of damage to the sensory organ ear, as well as the preservation of its functionality during noise work. Affected noise areas must be identified and the screening is mandatory. This occupational health examination is performed for all employees whose hearing is preserved. For persons with ENT-diagnosed profound hearing loss or deafness, employment in noise areas is possible without conducting hearing tests. The G 20 preventive examination must be arranged by the employer if the upper action value of the so-called daily noise exposure level 85 dB (decibel) or the peak sound pressure level 137 dB is reached or exceeded during the occupational activity at the workplace, since above these limits damage to hearing is to be expected. Noise work occurs in many occupations. Some examples are mining, iron and metal industry, woodworking construction industry, but also areas such as textile industry or paper industry.
Indications (areas of application)
G20 screening must be performed when working in noise areas with an upper action value of the daily noise exposure level of 85 dB (decibels) or a peak sound pressure level of 137 dB.
Before the examination
Prior to the examination, the employee’s hearing should not have been exposed to sound at an average level of > 80 dB for at least 14 hours. If this is not the case, the employee must take a break from noise to be eligible for the examination.
Procedure
The initial examination is performed before starting work, and the first follow-up examination is performed after 12 months. Further follow-up examinations depend on noise exposure should be performed after 30 months and after 60 months if the daily noise exposure level is below 90 dB or the peak sound pressure level is below 137 dB. A final examination is performed at cessation of work in noise areas. Early follow-up examinations are also possible. They are to be arranged in individual cases at the doctor’s discretion, at the request of an employee if he or she suspects a causal connection between his or her illness and his or her work activity, and if hearing disorders arise from an illness or accident. The examination program initially consists of a seventh test, which is a basic status survey and only leads to further examination if there are any abnormalities. This test can be performed by qualified personnel under the supervision of an occupational physician. The prerequisite for this is that the responsible medical professional checks the tests on a random basis. The seventh test, Noise I, includes the following components:
- Brief anamnesis
- Inspection of the outer ear
- Sound audiometry (medical measurement method for testing hearing with the measurement of volumes of different high tones that just cause a sensation of hearing) in air conduction (test frequencies 1-6 kHz).
- Advice on hearing protection
If pathological findings are found in this examination program, the noise II examination is automatically initiated, this should be performed by the occupational physician himself and consists of:
- Medical history
- Otoscopic examination (observation of the external auditory canal and eardrum).
- Weber test (synonym: Weber test; Weber test) Implementation: the foot of a vibrating tuning fork is placed on the crown of the patient. The sound is transmitted in phase to both inner ears via bone conduction. Normal hearing: Sound from the tuning fork heard equally in both ears (in the middle of the head), sound is not lateralized (lat. latus = side). Unilateral or asymmetric hearing disorder: tone of the tuning fork on one side, it is called “lateralization” (lateralization).
- Unilateral sound perception disorder: the sound is perceived louder by the better hearing (normal) inner ear (patient lateralizes to the healthy ear).
- Unilateral sound conduction disorder: the sound is heard louder in the diseased ear
- Hearing test in air conduction (test frequencies 0.5 – 8 kHz) and bone conduction (test frequencies 0.5 – 4 kHz or 6 kHz, depending on the type of device).
- Individual advice on hearing protection
If the hearing loss, which was determined in the noise II examination, is or exceeds 40 dB at 2 kHz then the extended supplementary noise III examination is required. This examination can be ordered by the occupational physician at an ENT physician. It includes:
- Otoscopic examination
- Sound audiometry in air and bone conduction
- Speech audiogram for both ears, and when justified indication:
- Tympanometry (middle ear pressure measurement).
- Determination of the stapedius reflex threshold – The measurement procedure records changes in impedance caused by, among other things, the stapedius reflex. In this process, the stapedius muscle (stapes muscle) contracts reflexively at high volumes, thereby stiffening the ossicular chain to protect the inner ear. Many diseases of the middle and inner ear, as well as the reflex arc, lead to deviating impedance values and are thus diagnosed with the help of the measurement.
After the examination
After the examination, therapeutic measures should be initiated according to the medical findings, or hearing protection measures should be followed.