One technique you will see seldom taught, even by those who teach 'dirty fighting', is the scream. Effects:
- Flinching of the head and body
- Alarms people nearby (usually what you want)
- Noise-induced hearing loss
A scream can generate around 100-125 decibels of sound pressure(loudness) (the world record is supposedly 112.8dB, but some say higher (125 at 8 feet away)). This is around the same as a jackhammer or power saw at 3 feet away. Whatever the scientific case, if you've ever had someone scream near your ear you know it's not pleasant.
When to use itYou'll most likely be in a grappling situation for this to work, but other situations such as a bear hug, clinch or anything similar literally head-to-head situation will work.
Generally if you're close enough to your attacker to pull off a scream directly in the ear you should be putting your fingers in his eyes/ears/nose. Of course though, simultaneous attack is always recommended if you can do it safely. In the case of screaming it's one weapon you have that you can employ with almost zero risk for counter-attack. Biting is somewhat dangerous because of blood-borne diseases. Screaming is a good alternative. Assess your situation appropriately.
Mixed martial arts (MMA) and screamingOn an interesting sidenote:
Ultimate Fighting Championship (UFC) rules and many other MMA sporting events do not explicitly state "no screaming". This is a pretty clear indication of how ineffective even professional fighters and some martial artists (incorrectly) view screaming. However there is of course an everything-clause:
22. Engaging in an unsportsmanlike conduct that causes an injury to an opponent.
So you probably still shouldn't do it.