Purpose of ear hook for open fit aids

I noticed that several manufacturers sell open fit hearing aids with an ear hook. The aid is identical to the aid without the ear hook but the fitting range may be 10 DB greater than the one without an ear hook. What is the reason that an aid with an ear hook may be more powerful than one without an ear hook?

As an example, the Sonic Innovations Ion 200 with an ear hook has a fitting range to 90 DB where as the one without the ear hook has a fitting range to 80 DB. However, the Sonic Innovations Ion has a fitting range of up to 80 DB with or without an ear hook.


The GN Resound Azure is similar. In its standard configuration it has an ear hook. But it can be converted to open fit thin tube by replacing the ear hook. And there’s a similar change in fitting range as posted above.

Is the aid with the ear hook no longer an open fit aid if it has a ear hook? Does it now become a standard BTE aid with a large tube and custom ear fitting? I guess I got confused since the aid was listed with the open fit aids and some manufacturers indicate the fitting range for that aid with a message such as With Hook instead of indicating BTE version.

When I demo’ed the Azure, it first came in with ear hooks. My audie used a “flex tube” with a tulip dome on the end connected to the ear hook until the open fit conversion kit came in. In the standard configuration, you’d normally attach a regular mold and tube setup to the ear hook, an yes, it’s just a regular BTE like that.

But I think the original question is what is it about ear hooks and molds that allows you to boost the device’s fitting range 10 or more dB. My guess is that it relates to feedback control, and a regular earhook, tubing, and mold would be much less susceptible to feedback, so you can boost the power a bit.

With my Pulse’s, which are strictly open fit aids, I’m using a tulip dome for feedback control, so my audie tells me, instead of the regular open domes.

The conversion kits are a clever way to offer the same product in two different presentation. The cost of having inventory is quite high and
often time companies have to find ways to reduce the number different parts…
I have told that some of the companies offer the same components
in their entire line of products and that they only make them different
with their fitting software. This way they can save $ as far as parts store etc…
I do not know if this is true, I had asked many time to dif. manufacturers
and i never got a straight answer…

Lovely Wendie99