There is quite a variety of hearing test currently available. A hearing test is generally done by an Audiologist to determine someone’s hearing capabilities or hearing threshold. This is necessary to understand how someone is ear is performing. A hearing test is conducted with an audiometer. During the test the patient has to listen to different sounds (Pure Tone Audiometry) at different loudness levels. The audiologist will then determine for several frequencies which is the lowest sound you can hear, which is considered the hearing level. It is done by presenting different sounds (pitches) to your left and right ear while a headset. A hearing test is complete pain free and can be done within 20 min.
In general everything below a threshold of 30 dB is considered a hearing loss, everything above as normal.
There are also other hearing tests available such as speech-test etc. Best is you speak to a qualified audiologist to find out which are the necessary test for you.