People often think that tinnitus and hearing impairment are naturally occurring phenomena after blast exposure, and if their symptoms resolve they do not seek medical advice. However, some of them may have substantial hearing impairment, particularly at high frequencies. Otologic consultation, or at least an audiometric screening test to exclude hearing impairment, should be performed regardless of symptoms, on the basis of exposure data only. Some symptoms, such as tinnitus and hearing loss, may be permanent consequences of a blast injury and their effect on quality of life may be substantial.

The average recovery of hearing both at high and speech frequencies was significantly better and tinnitus persisted less commonly after the HBOT than after the NBOT. Normal hearing at the end of the follow-up period was regained in 42 ears in the HBOT group and in 24 ears in the NBOT group (p<0.01).

We investigated the prevalence, characteristics and subjective perceived handicap caused by long-term tinnitus induced by acute acoustic trauma (AAT) in 418 former military conscripts. They had been treated between 1984 and 1989 because of AAT from exposure to impulse noise caused by firearm shooting. All 418 patients reported tinnitus after the AAT. At discharge from the military service, 122 (29%) still reported tinnitus. In 1999, of these 122 patients, 101 were reached and 66 still had tinnitus. The Tinnitus Handicap Questionnaire demonstrated various difficulties in life because of tinnitus, not attributable only to tinnitus loudness. Psychological factors also seem to play an important role. The effects of AAT and possible compensation have been evaluated so far mostly by audiometric findings, but in some cases tinnitus may be an even more serious threat to life satisfaction than mild hearing impairment.

In spite of strict safety regulations concerning firearm shooting, several hundred conscripts still suffer acute acoustical trauma (AAT) in the Finnish Defence Forces (FDF) every year, resulting in symptoms such as tinnitus and/or hearing impairment. The causes leading to AAT, causative weapons and mode and level of hearing protection were analysed to find out why so many AATs still occur in the FDF. The material consisted of 119 patients of the total 163 AAT patients treated at the Central Military Hospital during the year 2000. In 87.5% of cases, the AATs occurred in unprotected ears. The most common causative weapon was the assault rifle. Most of the AATs occurred during combat training in the field. Immediately after the AAT. 46.7% of conscripts had hearing impairment and 94.2% tinnitus. Hearing loss, tinnitus or both were experienced by 45% of conscripts at the last follow-up. Careful planning of training exercises could probably prevent some but not all AATs.

The degree of speech-frequency hearing loss was generally low, and a mention of tinnitus was reported in only 34 cases (4.0%). However, 88.7% of the patients actually had unreported tinnitus.