OMARA's Extreme Noise Management
Olivier Gaches and François Legros
Fighter planes and helicopters are places where very high levels of decibels can be experienced. Unfortunately, pilots, aircrew and ground staff are not fully protected against the danger and harmful effects of these high volumes with the possible result of unrecoverable damage to the human ear. Moreover, the pilots face situations in which alarms are not intelligible: this generates danger, stress and lack of performance. This situation also leads to tremendous costs (over 1 billion $ per year in the USA) due to the extremely large population suffering from hearing impairment. Moreover, the global trend is that the aircrafts generate a higher and higher level of decibels. Values as high as 160 dB were recently reported. OMARA provides a global solution.
The lack of performance is mainly due to the poor intelligibility of the signal.
First, the lack of intelligibility is caused by the excessive noise level that is experienced by the user. This situation is particularly dramatic if the noise spectrum is in coincidence with and overlaps the vocal spectrum. Second, the excessive noise level induces a stress level, a cause of lack of awareness. This is particularly the case of the pilots in the combat conditions, especially with the extension of the flight durations. Third, the long term exposure to very high noise levels induces a progressive loss of the hearing capability. The signal to noise ratio becomes critical because the perception threshold of the user becomes too high.
The hearing impairment is a complex phenomenon which has to be detailed in order to deploy a consistent strategy.
The most critical part of the frequency spectrum is the 4 000 Hz region, which is the first damaged spectral zone in case of excessive noise exposure. The approach may be active (the active noise reduction technique) or passive (acoustic filtering). The active noise reduction technique leads to an efficient response in the low frequency part of the spectrum (100-300 Hz). The acoustic filtering is an efficient way to remove the noise which spectrum lies in between 1000 and 10 000 Hz.
Amplifon Switzerland designed a customized solution based on a unique combination of acoustic filtering techniques. A highly efficient silicon based earmold is associated with a customized miniaturised acoustic filter and receiver so to provide an optimized attenuation of extreme noise in a broadband spectrum.
OMARA's purely passive approach avoids the use of batteries, allows a friendly use of the product and ensures both:
immediate performance for the users (enhanced environment awareness due to perfect intelligibility of provided information in extreme noise), and guarantee a long term hearing capability. As such, OMARA provides a sustainable solution to dramatically.
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