Our REM probe tubes markers are positioned 30mm from the tip of probe tubes because this is the average distance between the eardrum and the inter-tragal cavity of the average adult males according to Pumford & Sinclair (2001) :
| Adult females | 28 mm |
| Adult males | 30-31 mm |
| Children | 20-25 mm |
In the 2016 vol 3 issue 5 of the Canadian Audiologist journal, Jonathan Vaisberg, PhD, Ewan Macpherson, PhD et Susan Scollie, PhD compare the influence of REM probe tube placement for a bandwidth of 10KHz.
Standing waves can then cause a reduction in amplification gain at several locations in the ear canal and thus reduce the effectiveness of the hearing correction measurement.
There is also a negative influence on the mechanisms for determining frequency averages used in certain electro-acoustic analyzers, particularly those which use a tier of octave method (such as Audioscan’s Verifit 2).
They demonstrated that a deviation of 2mm in probe placement leads to very different measurements, especially at higher frequencies (from 4KHz to 10HKz).
The conclusion is that the closer the probe is placed to the eardrum, the higher the precision and the repeatability of the measurement. This is why the markers on our probes are placed 30mm from the tip of the probe.
Buy here : https://en.earkey.ca/product-category/probe-tubes/