Real Ear Measurement

Real Ear Measurement is a term used for all measurements done directly on the client's ear. These measurements can be done with or without the hearing instrument being worn. The reason Real Ear Measurement is done for hearing instrument fittings is because shape and size of an ear canal significantly influence a hearing instrument's performance.

As the shape of the ear is unique to each individual (like a fingerprint), without Real Ear Measurement, only average data can be used.

Without proper measurement, this can lead to over or under amplification of the hearing instrument. For adults who can effectively describe if they perceive the sounds as too loud or too soft may not have such a problem. However, when it comes to babies, small children or some mentally handicapped who do not have the ability to describe their perception verbally, it can lead to the problems mentioned above.

How does Real Ear Measurement works?

Sounds are presented using a loudspeaker in front of the test person. A microphone is located close to the ear to measure the sound's intensity. A second microphone measures the sound's intensity directly inside the ear canal in front of the ear drum.

Knowing the intensity of the sound inside and outside of the ear enables the filter to determine the actual amplification and output the testee receives through the hearing aid and make the appropriate adjustments.

Real-Ear-to-Coupler-Difference

Real-Ear-to-Coupler-Difference is one form of Real Ear Measurement. Real-Ear-to-Coupler-Difference uses the fact that many hearing instrument shops have a hearing instrument analyzer . This analyzer is frequently used to adjust hearing instruments for clients. However, the coupler used in such an analyzer usually has a size of 2cc which is much bigger than the ear canal with an ear mould inside. As a result hearing instruments adjusted by means of an analyzer will be too loud (especially for children with their very small ear canals). On the other hand, doing Real Ear Measurement as described above can be quite difficult because the child must sit still and may not make noise.

Real-Ear-Coupler-Difference is the solution to this dilemma. In RECD, a signal will be measured once with the analyzer’s coupler and a second time in the ear of the child while wearing the ear mould. Now, knowing how the instrument performs in the ear and in the coupler, the difference can be calculated (RECD). The hearing instrument can now be adjusted in the hearing instrument analyzer taking its real ear performance into account.

Once a Real-Ear to Coupler-Difference data is obtained, the child is not required to sit still during the adjustment. In fact, the child need not even be present after the data is obtained, and an accurate adjustment can still be made.