While not Deaf, you don't hear so well. You take a −2 penalty to all checks for which hearing is a factor (typically Perception, Search, Translate, etc). You are completely deaf to high-pitched sounds, such as the whistle of an approaching arrow or a beeping time bomb.
Note on hearing correction: As with vision-correction, there are some devices which can amplify sounds and correct a character's hearing, effectively negating the penalties suggested above, but only while the device is worn. These items are even harder to find and more expensive than vision-corrective items and may be non-existent in some stories. Anytime a character with a hearing-corrective device rolls a critical failure, the device is lost and the character must spend time searching for it, during which time the usual hearing-related penalties return.