What happens is that the eardrum or ear canal is damaged. A torn or punctured ear drum can cause hearing loss. Trying to remove the object yourself can risk further injury. It is better to have a doctor remove it because the doctor will have the right equipment to do it safely.
The only foreign objects in the ear that you should try to remove yourself are those that can be seen easily, are soft, and can be pulled out easily with your fingers or tweezers. One way to remove such objects from the ear is to turn the head down and gently shake it to try to make the foreign object fall out. If a bug got into the ear, oil can be used to try to suffocate the bug. But it won't necessarily come out -- you might still have to go to a doctor.
Ear Injury and Hearing Loss Statistics
Fortunately, hearing loss from ear injury is rare. The National Center for Health Statistics puts out a publication on the prevalence and characteristics of people with hearing loss, including their reported causes of hearing loss. In this publication, the "ear injury" category combines both ear surgery and ear injury. Table 16, "Percent distribution and number of reported causes of hearing trouble of persons 3 years of age and over by type of cause, according to type and age at onset of reported hearing trouble," has a row for ear injury. In the 1991 table, the percentages were:- For all ages without regard to age at onset of hearing loss, 4.9 percent.
- For those who became hearing impaired before age 19, the percentage rises to 9.6 percent.
- For those who became hearing impaired after age 19, the percentage drops to 3.7 percent.
Sources:
National Center for Health Statistics: Publications and Information Products: Data from the National Health Interview Survey: Series 10, No. 188.

