OTOFONIX HELIX User Manual page 25

Domes
Different Domes can completely change the sound and feel of your hearing device.
An Open Style Dome has large vent holes and is intended for people with the typical
mild to moderate high frequency hearing loss who do not need much amplification in the
low frequencies. The larger openings in the dome allow for low frequency sounds to pass
though the dome with minimal amplification and a more natural sound. It eliminates the
"occlusion effect" which is similar to putting your fingers in your ear and hearing yourself
talk. On the negative side, open domes are the most prone to feedback (whistling).
A Close Style Dome has no vent holes. This allows the device to boost the sound levels
as much more aggressively as 20 dB, especially in the low speech frequencies. Often
closed domes are the better answer for people suffering from a more severe level of
hearing loss. These domes virtually eliminate all feedback that occurs from higher
amplification, but they also maximize the "occlusion effect" .
A Magic Dome is a hybrid open/closed ear dome. It looks like 2 domes stacked on each
other with small slits rather than large vents as found on open ear domes. Overall the
magic domes also significantly minimizes the "occlusion effect" and reduces feedback,
making them more comfortable than the closed domes. These domes are recommended
for those with a mild to moderate hearing loss.
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