User:Cstokesrees/draftREM2

Real Ear Measurement (REM, also known as insitu- or probe microphone measurement) is the measurement of sound pressure level in a patient's ear canal developed when a hearing aid is worn. It is measured with the use of a silicone probe tube inserted in the canal connected to a microphone outside the ear and is done to verify that the hearing aid is providing suitable amplification for an patient's hearing loss. The American Speech–Language–Hearing Association (ASHA) and American Academy of Audiology (AAA) recommend real ear measures as the preferred method of verifying the performance of hearing aids.

Used by audiologists and other hearing healthcare practitioners in the process of hearing aid fitting, real ear measures are the most reliable and efficient method for assessing the benefit provided by the amplification. Measurement of the sound level in the ear canal allows the clinician to make informed judgements on audibility of sound in the ear and the effectiveness of hearing aid treatment.

Method
First, the clinician will examine the ear canal with the use of an otoscope to ensure no wax or other debris will interfere with the positioning of the probe tube. The probe tube is placed with the tip approximately 6mm from the tympanic membrane. Next the hearing aid is put in place. The REM system will typically produce a test stimulus from a loudspeaker situated 12-15 inches from the patient's head and simultaneously measure the output in the ear canal to determine how much amplification the hearing aid is providing.

Insertion Gain
The traditional method of real ear measurement is known as insertion gain, which is the difference between the sound pressure level measured near the ear drum with a hearing aid in place, and the sound pressure level measured without. First a measurement is made with the probe tube in the open ear, then a second one is made using the same test signal with the hearing aid in place and turned on. The difference between these two results is the insertion gain. This gain can be matched to targets produced by various prescriptive formula based on the patient's audiogram or individual hearing loss.

Speech mapping
Speechmapping (also known as output-based measures) involves testing with a speech or speech-like signal, with the goal being to amplify it to the approximate middle of the patient's residual auditory area (the amplitude range between the patient's hearing threshold and upper limit of comfort). This allows the clinician to adjust the hearing aid to optimize speech audibility while avoiding loudness discomfort. This approach to hearing aid testing is implemented in most current real ear systems and there has been a significant increase in audiologists selecting to verify using the output method. Using an authentic speech signal to test a hearing aid gives the advantage that the hearing aid can be tested with all its special features operative. The impact of those features can be viewed just as they would normally affect speech in real life.