How do you know when you've got the perfect seal?

I did a closed mouth impression the first time and the fit was too loose...especially when i opened my mouth to sing.  You need to go back and get a bite block open mouth impression unless you are ok breaking your seal and reseating the monitor all day long. 
 

 

It varies from person to person.  My audiolodists has done impressions for 30 years and in his opinion the bite block is not necessary.  I did not use one and JH Audio made my impressions to perfection.  You will just know when you have a good seal.  It will feel right.  Sort of like when pressing on them to try to seal them better makes no improvement you know it is right.

 

I believe I read somewhere that custom fits get it right the first time over 95% of the time which are pretty good averages.  Not sure where those stats come from.  Perhaps it was JH Audio's own track record.

Full sound (deep bass, clean highs); even balance L/R; impact on drums, bass guitar; sense of seal and pressure even in both ears.

You pee from a great hight into a receptacle in which there is water (okay, maybe an empty can) - so, this is mostly for the lads here - and if you don't hear anything (pee hitting water), then you have a brilliant seal.  The key here is to watch carefully what you're doing, otherwise.....

 

You will know when you no longer hear ambient noise that you have a good seal, is what I am trying to say.  The test I suggest does have it's merits, though.   After my second pair of JH13s, I went on a long flight and, yes, there was some background noise from the aircraft engines, but really muted,   I could not hear any PA announcements, so be careful if you're about to take a dive!  Maybe another indicator of a good seal.  Also, I have worn the JH13s for over 7 hours with no discomfort whatsoever.   I do, however, suggest you remove them before beginning any descent on a plane.   Having them in my ears prolonged the pooping of my ears until well after we landed.

 

I had a bad time at first with my seal (impressions done by Sonus - JH Audio recommended - with a bite block) and sent my JH13s back at least four times for a little bit of acrylic here, a little bit there, until JH Audio suggested new impressions.  Jerry Harvey recommended an audiologist in the LA area and she did my second impressions.  The build off those fit perfectly.  The amount of time the material sat in my ears was much less than that at Sonus.   I often wondered if given how much time the material was in my ears if I swallowed - apparently a no-no - and that ruined the impressions.  There are a lot of variables at play here and, consequently, room for error......or bad fit.

The complainers are always more vocal than the satisfied customers.  Unless there was a dedicated thread about "who got the fit right first try", it would be hard to really know.
 

 

Here's the thing: The shape of your ear canal changes when you move your jaw. Thing is, there is no way predict whether it gets bigger or smaller. In fact, with some people, the left and right ears will behave differently! So the use of a bite block may help, or it may screw things up. This is not an exact science.

 

Remember IEMs were originally created for musicians. Most all of them - but especially vocalists - are changing their facial expressions throughout a show. When the seal is lost, bass response is seriously compromised through the leak.

 

It's my theory (and only a theory) that the bite block idea originated as a way to maintain seal during vocals. And it obviously helped enough people that it has become recommended practice with some (but not all) manufacturers. OTOH, home listeners are much more stable while listening. A good fit should be obtainable without a bite block, especially if you listen with your mouth closed.

 

This is the part where I sing the praises of silicone earpieces, like all Sensaphonics models. They flex with your canal, maintaining seal through a wide range of motion. They are also soft, and thus more comfortable.

 

Sensaphonics does not recommend the use of a bite block when getting impressions. Quoting from the company's "Getting Ear Impressions" PDF:

 

 

Obviously, this procedure is designed for musicians, and our percentage of refits is quite low. My point here is that pointing to bite blocks, swallowing, etc., as causes for bad fit oversimplifies the issue. Again, this is not an exact science, and what works for one person may well create problems for another. This is the whole reason that custom manufacturers offer refits.

Edited by JackKontney - 4/22/11 at 1:03pm

If when you lose a ton of bass response while lying flat on your back, then you seal is not tight enough.

when it brings you breakfast in bed, and opens your beer for you. 

I don't know, perhaps it mimics a jaw thrust and by pushing the jaw away from the head, it let's a bit of air in. I've noticed that with my acs tips (Etymotic), the seal is constant, lying flat on my back; but with other tips, on my back, the bass (therefore seal) decreases.