Noise Level
Noise Level
(OP)
Hello !! I am currently facing a small problem. I am installing an avionic equipment in an helicopter. And I wonder if it is possible with a simple analysis to determine if the alarm produced by my equipment will be correctly audible by my pilot. Knowing that my equipment will be installed on an unswitch input of my audio panel not allowing the pilot to turn down the volume of this alarm for safety reasons. I would like to make a small calculation only for my personal knowledge. Even though I know that the equipment is standard and that my pilot will hear this alarm. I am just curious and would like to know how with a calculation we can say that we are confident that the alarm will be audible.
The ambient noise level of my rotorcraft is 115dB
My equipment has the following characteristics:
- 600 ohm -> 0.625 to 80 mW
My audio panel has the following characteristics:
- Input impedance: 500Ohm
- Input Isolation: 60dB minimum
The speaker has the following characteristics:
- Output power : 10 Watts into 4 or 8 ohm
I have been asking myself this question for a very long time, whether it is possible or not, but unfortunately I don't know the audio world very well. If you have an answer to my question + explication I'll be able to finally sleep well ahah
Thank you very much for your help
The ambient noise level of my rotorcraft is 115dB
My equipment has the following characteristics:
- 600 ohm -> 0.625 to 80 mW
My audio panel has the following characteristics:
- Input impedance: 500Ohm
- Input Isolation: 60dB minimum
The speaker has the following characteristics:
- Output power : 10 Watts into 4 or 8 ohm
I have been asking myself this question for a very long time, whether it is possible or not, but unfortunately I don't know the audio world very well. If you have an answer to my question + explication I'll be able to finally sleep well ahah
Thank you very much for your help
RE: Noise Level
And there are rules about how loud a sound needs to be to be heard against the background but I don't recall them.
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P.E. Metallurgy, consulting work welcomed
RE: Noise Level
another day in paradise, or is paradise one day closer ?
RE: Noise Level
RE: Noise Level
For this reason most helo pilots, crew and Pax will be using/wearing high quality heads-sets which block-out/muffle/cancel ambient noise yet receive all aural comm/nav/system/warning tones/notifications/messages with clarity. IF this is the case, then human factors with this 'primary' aural channel... hearing quality... is always a wild-card.
IF my presumption is real, then multiple/arranged/discrete/directional cabin speaker(s) or piezoelectric devices will be required to flood the cockpit/cabin with their warning tones/notifications/messages directly... along with these same messages/tones in the headsets.
A series of flight tests of various speakers/piezoelectric devices-configurations, with people having various hearing issues/degradation in the nominally loud environment... having high quality headset with volumes 'starting at full-down/off'/rising to max volume for emergency notifications... may be the simplest to way to validate Your design for the real world.
NOTE. People, seat arrangements, insulation, window panes, mechanical components [engines, transmissions] and wind-noise, at various flight conditions will all play various damping/muffling roles.
Regards, Wil Taylor
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RE: Noise Level
RE: Noise Level
another day in paradise, or is paradise one day closer ?
RE: Noise Level
https://www.hptinstitute.com/wp-content/uploads/20...
A tone by itself seems to be a popular, but not always effective, way to alert a crew to problems in a machine with so many variations of trouble. It may make things worse if pilots decide that they don't need to frequently scan the instruments, confident that an alarm will draw their attention should a problem arise. In one case to solve this problem the Mooney Mite, famed for being the smallest production plane with retractable landing gear, they added a device that flicked back and forth in the sightline of the pilot to remind pilots to put the gear down when the flaps and throttle were set suitable for landing. This was due to the large number of wheels-up accidents.
RE: Noise Level
2) they needed a dog in the cockpit ... a big, nasty, angry dog (to keep the pilots from touching things).
another day in paradise, or is paradise one day closer ?
RE: Noise Level
RE: Noise Level
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P.E. Metallurgy, consulting work welcomed
RE: Noise Level
They are designed to generate a "white noise" to cancel the environmental noise.
The alarm is a "pure tone" and might not be modulated, so there is a chance that the headset could cancel it, more or less.
You want to patch it into the audio system AND put it on speaker.
This is a solved problem. I helped solve it, on a project years ago.
You seem to be past the point of already selecting the equipment, but just in case...
These folks can tell you something about how to make your alerts work. https://www.jupiteravionics.com/productalertgenera...
My project was done for these folks (see attached):
RE: Noise Level
That operator isn't in business any more.
RE: Noise Level
another day in paradise, or is paradise one day closer ?
RE: Noise Level
RE: Noise Level
TTFN (ta ta for now)
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