As we learn more about how what we use affect the environment we will see our products change. When I started my first “real” audiology job there was the change to use the zinc air batteries from silver and mercury. There were some patients who complained up a blue streak about how the battery life changed. I since have experienced a few more major changes with the batteries used in hearing aids. 
The latest is the Mercery Free batteries from all of the major manufactures. There have been changes in the past that the battery makers have made without reporting the them to us and we had unexplained happenings with the hearing aids. Two years ago, it took three months of talking with the hearing aid manufacturers, the battery distributors and the battery makers to find a sealant that was being used was changed. This changed the contact on the batteries and the aids would go through a start up procedure randomly.
Caliper
I am again faced with intermittent changes with how hearing aids are reacting with the new Mercury Free batteries. What I sometimes get frustrated with is the hearing aid manufacturers tell my offices it would not happen with the batteries I would buy from them (it has) and it does not happen all of the time. I have not been able to pinpoint to a single entity. Except for a colleague measuring the batteries with her caliper and finding one of the battery companies have smaller batteries physically than the other makers. This would definitely affect the contact and give random intermittency.
So, what I have learned through this is don’t always be content with the first answer. Not everyone will say “I don’t know, let me find the answer for you.” At times I find I have to get the same answer repeatedly from different sources when I feel there is something amiss, maybe Irish stubbornness, but I still feel there is something about the Mercury Free batteries that is just not working like we are use to. Have you found anything in your offices?
