How Not to Take an Ear Impression, filmed by BBC at Royal Berkshire Hospital: This YouTube video is so wrong, on so many levels!
One of the ingredients in a successful hearing aid fitting is to start out with a carefully made ear impression, so that you end up with a comfortable earmold or shell that causes no instability (squealing from “feedback”); and to this end we at The Hearing Blog have been keeping an eye out for a good video to show our readers what they should look for from their hearing aid professional.
However, this BBC Berkshire YouTube video by correspondent Anne Diamond shot in the Audiology department at NHS’ Royal Berkshire Hospital is so wrong, on so many levels, that it merits “featuring” in The Hearing Blog.
Let’s start by watching the video; but don’t bother to turn on the captions, as they are missing:
For starters, the BBC Berkshire production values are terrible: Besides the first problem of no captions, the lighting is terrible, and Diamond’s right arm is blocking the camera view of the hearing aid professional kneading the silicone impression material.
What’s more, at least in this clip, there was no showing of the ear preparation, including the otoscopic inspection and the placing of the otoblock.
Also, from both the procedures shown and supplies in view, it appears no infection control procedures are being used.¹
Next, the professional does not appear to measure the quantity of accelerant used in the condensation cure silicone impression material; nor does he wash his hands before kneading the impression material, as if there has been any hand lotion used, it will cause curing problems.
The professional takes over 45 seconds to knead the impression material: Whether condensation or additive cure silicone² impression materials are used, it is vital to mix the components as quickly as possible, as it starts to cure in less than 30 seconds, gaining viscosity in the process.
Finally, we don’t even get to see the finished impression!
There’s a Yiddish phrase that accurately describes this video: Oy vey!
- Infection control is vital in every hearing aid dispensing and audiology practice. Our friend Dr. A.U. Bankaitis, Vice President of Oaktree Products in St Louis, is an expert in the area, and we suggest reading her excellent series of articles on this vital subject;
- Silicone (actually vinyl polysiloxane) ear impression material comes in two varieties: Condensation cure, and additive cure. These are room temperature vulcanizing (RTV) polymers that cross-link to cure; and the way to tell them apart is that condensation cure material uses a small amount of an accelerant, while additive cure material uses a 50:50 mix. For more on the impression materials used, please see Viscosity vs Hardness of Ear Impression Materials.
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