Most common tinnitus cause I. - What is acoustic trauma

The most common cause for tinnitus is so called acoustic trauma, or the hearing damage by exposition to loud noise. Shooting without hearing protection, fireworks on Fourth July, New Year and other celebrations, petards, motorcycle exhaust strokes without noise reduction, loud music at concerts, discoteques or pubs, workplace with constant high level of noise - all that can be marked as source of acoustic trauma. Cases are known, and not at all rare, that individual caused himself tinnitus by listening to the loud music in car or using MP3 player.

Acoustic trauma generally arises in all situations where ears are exposed to very loud noises for long enough to ensure that the sensory cells are metabolically exhausted. Noise intensity of 140 db or more causes such exhaustion immediately (e.g. shot, explosion etc.). We can say that the cell is literally drowning in their own secretions (various forms of aggressive oxygen free radicals etc.), which it cannot degrade fast enough. After a short time apoptosis (programmed cell death) begins. Unlike birds and reptiles, by mammals dead neuro cells are not replaced by new ones, so the loss is permanent. However, cell death does not occurs instantly, and here is a chance to repair the damage.

Too loud!

Early sign of acoustic trauma is temporary deafness. Overloaded hair cells temporarily cease to function, those most damaged forever. Hearing gradually begins to return to its original value, but never to such state as before acoustic trauma (also depends on the actual severity of acoustic trauma). I myself have realized few days after acoustic trauma, that I hear a little bit worse.
Unfortunately, it still does not stop here. Some research has shown that stabilization of hearing after acoustic trauma can last up to five years from the moment of acoustic trauma, and may get even worse during that time. It is probably related to the gradual death of damaged hair cells, which have survived the acoustic trauma itself, but perish after a few months or years. It also means favorable forecast to gradually improve potential tinnitus, which often accompanies acoustic trauma.

Acoustic trauma results in loss of perception of higher frequencies, shift in the perception of sound (depending on the degree of severity) and distinctive hole in the zone near 4000 Hz. If you stop hearing in 15 kHz band, you do not need to worry much, these are not frequencies that commonly occur in life. But 4 kHz occurs commonly and hearing loss manifests as follows: the sound is blunted, like when you mute heights in equalizer. Everything sounds somewhat differently and you have decline in quality of perception.