A hearing test measures two variables: loudness/volume (decibel level of dB) and pitch or tone (frequency in Hertz or Hz). It measures at which decibel level the patient first hears the sound of a particular pitch, which is indicated by pressing a Yes or No button.At 1,000 Hz, for example, a person may first hear a sound at O dB or10 dB. Zero dB is not no sound, but rather the quietest end of the range at which normal hearing begins to detect sound. Normal range of hearing for healthy young people is between 0 dB and 25 dB.An audiogram measures the decibel level at which sound is first heard for a number of frequencies or pitch levels. For instance, the US AMA system tests the dB level at 500 Hz, 1,000 Hz, 2,000 Hz and 3,000 Hz.It is possible to temporarily "numb" the ears by sustained exposure to loud disco music or concentrated use of a Walkman at high volume, but malingerers are easily detected by repeat testing or use of a CER test which measures involuntary brain reactions to sound. Faking is not widespread, particularly as serving soldiers regularly undergo audiograms outside a legal context.Human hearing ranges from 20 Hz to 20,000 Hz, but normal conversational frequencies vary from 250 to 4,000 Hz. Telephone lines do not carry sounds above 3,000 Hz, yet are adequate for carrying human speech.Soldiers are claiming for hearing damage suffered as a result of being exposed to the noise of guns and artillery. Audiograms produced from tests on many of them show hearing loss at 4,000 Hz. In other words, their hearing was damaged in that it was not as good as it should have been when it came to hearing sounds of this frequency. The sound of an E-string on a violin comes in at 4,000 Hz.Most ear nose and throat (ENT) specialists say a hearing loss at 4,000 Hz would have little or no effect on the understanding of speech against a background of noise. In their view this is not a disability or handicap, although hearing loss due to gunfire, for example, can be pinpointed at such a frequency. Moreover, lawyers and ENT specialists representing soldiers point to hearing difficulties for soldiers in social settings linked to this damage.The AMA system is a measure of hearing handicap associated with a particular hearing loss. It is widely used as "an international standard", though its critics say an administration will adopt the system that minimises liability. The UK has a system with similar elements but it takes more account of loss due to ageing.Analysis of 649 cases against the State shows that 80 per cent have no hearing disability/handicap (as against no hearing loss). Applying tests used by the British army, only 10 per cent of claimants would qualify for compensation.Applying the AMA system would rule out 70 per cent of claimants. Most of the remainder would receive less compensation than they have in the absence of an accepted system in Ireland, where conflicting medical opinion has led - perhaps understandably - to courts siding in favour of soldiers.In some cases, older soldiers have received compensation by the application of a baseline reference of hearing ability more appropriate to a normal healthyyoung person. The issue of tinnitus has also been problematic. Some 90 per cent of claimants say they have a high-pitched ringing sound in their ears. There is no scientific test to confirm this.Under the auspices of the Department of Health, an expert group is due to report this month and recommend an Irish standard for measuring hearing loss.
