Moisture Related Failures

1
Moisture Related Failures

• Cause, Effect, Solution

Daniel R. Schumaier, Ph.D. Ear Technology
Corporation
2
We Deal With the Effects of Moisture on Hearing
Aids Every Day

• Corrosion
• Switch Problems
• Microphone Speaker Failure
• Distortion
• Loss of Clarity

3
Causes of Moisture in Hearing Aids

• Accidents or Negligence
• Cerumen
• Perspiration
• Environmental Conditions (Condensation)
• Temperature
• Humidity

4
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.

5

• 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.

6
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.

7
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.

8
Condensation Example

• Weather Report
• Relative Humidity 60
• Temperature 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.

9
What Do Arizona Alaska Have in Common?
?
Extreme Temperature Changes that Promote
Condensation
10
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

11
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 dont except by
  random chance.

12
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.

13
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.

14
Conclusion
3 Things Necessary to Dry a Hearing Aid

• Heat (controlled amount)
• Moving Air (circulating around the aids)
• Desiccant (moisture released must be adsorbed)

15
Solution Dry StoreHearing 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

16
Dry Store has greatly improved the quality of
my sons 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

17
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

18
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

19
The Bottom Line
98 of regular Dry Store users said they were
satisfied! (64.6 said outstanding or very
satisfied)