Vmax8
Quote:
Using my helmet in a R22 or R44 is kind of a problem, as the low RRPM warning horn gets so muffled by the sound isolation of the helmet, that it's hardly noticeable. Therefore I prefer not to use a helmet on these aircrafts as I worry I won't hear the horn in a low RRPM situation. Is there any solution to it?
I don't think a helmet gives much more 'muffling' than a decent headset, does it? [IMG]file:///C
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If a warning horn is not properly audible when putting your helmet to its correct use, then the problem lies with the audio warning design, not the helmet. The helmet is designed to provide passive attenuation to a given specification, and active attenuation if ANR is fitted. The helmet is part of, for example, the intercom system, which is part of the aircraft, and all must be properly integrated. Few are, as you’ve discovered.
By design, a typical aircrew helmet, say the Mk4, will provide better passive attenuation than a headset. Attenuation is frequency dependent. The crucial area is low frequency (defined as 40 – 1kHz), where attenuation tends to vary a lot often due to ill-fitting helmets. Performance tends to be much better in the high frequency (above 1kHz) but this is not where the problem is (i.e. damaging noise, as opposed to annoying noise - a different but related subject). Hence, most ANR systems are designed to work in that lower region.