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 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 / p sat 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: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.

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 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. Closed Containers (Hearing Aids) are Difficult to Dry

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 Heat (controlled amount) Moving Air (circulating around the aids) Desiccant (moisture released must be adsorbed) 3 Things Necessary to Dry a Hearing Aid

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 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

…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)