An audiometer is a device used to evaluate hearing loss during an audiology test. Usually, it is an individual piece of hardware that delivers pure tones of controlled intensity to one ear at a time, to which a patient responds when they can hear the tone. Many modern devices can either be used alone or connected to a computer and integrated with hearing conservation databases.

There are two main types used today. There are Objective and Subjective Audiometers. Objective audiometers do not require any "work" from the individual being tested while subjective audiometers require the patient to be alert, awake and able to respond to the testing stimuli. Objective audiometers:

Objective audiometers

(1)  OAE’s- acoustic Emissions is usually used to screen babies 
(2)  ABR- Auditory Brainstem Response looks at the pathway in the brain leading from the cochlea nucleus all the auditory cortex for responses
(3)  Impedance/Reflex testing checks the ear drum movement and auditory reflexes from the middle ear 
   
Subjective Audiometers- Behavioral responses required, patient must be awake and alert
         (1) Type I- Fully equipped with capabilities for pure tones, bone conduction, masking and speech tests, loud speakers for sound field testing
         (2) Type II- Full Audiometer but without loud speakers
         (3) Type III- Portable Audiometer without speech testing capabilities 
         (4) Type IV- Type 4 is a screening audiometer is pure tone testing capabilities, sometimes there is a limited number of tones and intensities on the screening audiometer

  *There are also several outdated audiometers not listed here because they are so rarely used except in research