Transcript Fish Love It, Hearing Aids Don`t

Moisture Related Failures
Cause, Effect, Solution
Daniel R. Schumaier, Ph.D.
Ear Technology Corporation
We Deal With the Effects
of Moisture on Hearing
Aids Every Day

Corrosion

Switch Problems

Microphone & Speaker Failure

Distortion

Loss of Clarity
Causes of Moisture in Hearing Aids

Accidents or Negligence

Cerumen

Perspiration

Environmental Conditions
(Condensation)
 Temperature
 Humidity
Previous Studies

1967, Bruner & House: found RH in
external ear canal always above 60%.

1996, Bailey & Valente: study done for
Eveready Battery Co. to determine effect
of humidity and temperature on zinc-air
battery life. In-vivo studies, majority
done at ambient temperature of 60-80
degrees F & RH below 50%.

1999, Agnew (AAS presentation in 4/99):
custom ITE worn in right ear, 100
measurements across USA, found that
ambient RH and the RH inside the ITE
tracked more closely than expected.
Therefore, the operating environment
inside an ITE was not as extreme as
previously assumed.

Nevertheless, moisture causes a huge
non-recoverable monetary loss to the
industry, and loss of patient satisfaction
that ultimately impacts sales.
Relative Humidity
The ratio of the quantity of water vapor
actually present in the air to the
quantity that would saturate the air
at the existing temperature:
RH = p / psat X 100%
“Relative” means relative to temperature. Warm air
holds more moisture than cold air. As the
temperature drops, condensation chances go up.
Dew Point
The temperature at which the air can
not hold additional moisture at
any given temperature (saturated).
Further decrease in temperature
will result in condensation.
Condensation Example
Weather Report:
Relative Humidity:
Temperature:
60%
90 F
Complicated formula, but in this case the
Dew Point is 75 degrees F.
It means that condensation will be formed
in the hearing aid even before the
hearing aids reach room temperature.
What Do Arizona & Alaska
Have in Common?
?
Extreme Temperature Changes
that Promote Condensation
What is Needed to Remove
Moisture from Hearing Aids?

Controlled Amount of Heat

Breaks surface tension – smaller drops

Reduces capillary pull (receiver tube)

Reduces the “Glue Effect”
II. Moving Air
Closed Containers (Hearing Aids)
are Difficult to Dry



Air circulation initiates natural diffusion
effect (wet to dry).
Without controlled airflow, vaporized
moisture will re-condense when
temperature drops below dew point.
Active systems cause moisture to move
out of the hearing aid. Passive systems
don’t – except by random chance.
III. Charged Desiccant

A desiccant is a substance with high
affinity for moisture molecules.

Moisture released from the hearing
aid must be physically removed,
otherwise it will redeposit/condense
elsewhere.

Desiccant efficiency is temperature
dependent.
Why Not Just Heat the Aid?

Heat alone without moisture removal
can create a “corrosive soup.”

Warm a small amount of water in a
covered pan. When the pan cools, water
inside recondenses when the
temperature drops through the dew
point, dripping off the lid when it is
removed.
Conclusion
3 Things Necessary to Dry a Hearing Aid

Heat (controlled amount)

Moving Air (circulating around
the aids)

Desiccant (moisture released
must be adsorbed)
Solution: Dry & Store
Hearing Aid Conditioning System



Three patents
Only product to
combine the three
needed technologies
for drying closed
containers
UV light that reduces or
ends itching ears or
recurring otitis externa
“Dry & Store has greatly improved the
quality of my son’s life in the summertime.
He was constantly having to get his hearing
aids cleaned or repaired because of sweat
damage. Thank you! Thank you! Thank
you!” F.B., Georgia
“An exceptionally fine product that
exceeds the claims made for it.”
W.N.C., Florida
“…the unit [Dry & Store] was the key to my
feeling comfortable with wearing hearing
aids in that it provides a wonderful sanitary
place for overnight storage plus the added
benefit of drying any wax present to dust…
Excellent!” C.S. Brien, Maine
“My aids would be lost without
Dry & Store.” S.L., Athens, Georgia
User Survey Results




(5/99)
77% said their hearing aids
sounded better.
72% said itching or recurring
infections were eliminated or
reduced.
54% said batteries lasted longer.
67% said need for repair was
eliminated or reduced. AND…
The Bottom Line…
98% of regular Dry & Store
users said they were
satisfied!
(64.6% said “outstanding”
or “very satisfied”)