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On a recent passenger flight my son asked me, "How come we're able to build a 737 for \$50M - \$80M with fantastic reliability and technology but can't design a PA system so that we can understand the pilot's announcements?" Many are quite un-intelligible but the cabin crew announcements generally are intelligible. I didn't have a good answer. Does anyone know?

As a follow on and of more concern, if pilots' microphone technique / equipment is so poor then how does air-traffic control understand them? I know there is a limited vocabulary set and that standard phrases are used to avoid mis-hearing but there must be some problems.

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    $\begingroup$ Is this an actual question? I've had no problem hearing the announcements so far. It seems the microphone is good enough to work for ATC, as there is only one. You may listen to ATC feeds to convince yourself (and your son). $\endgroup$ – mins Apr 17 '16 at 10:24
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    $\begingroup$ @mins as there is only one no there isn't, and I suspect that this might be the problem. All of the big iron cockpits I am familiar with have a hand mike, and I've seen the flight crew use this for cabin address in preference to the headset boom mike. I suspect that the maintenance on this might not as rigorous as for the headsets and, if the quality is poor, does anyone bother to raise a maintenance snag for it? $\endgroup$ – Simon Apr 17 '16 at 11:37
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    $\begingroup$ @mins. they use the same device for radio and PA. Sorry to be a pain, no they don't. There is almost no commonality other than the ability to select either mike as the input source to PA or radio. The comms selector panel is the only common piece and this is little more than a set of switches. $\endgroup$ – Simon Apr 17 '16 at 12:09
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    $\begingroup$ Related: aviation.stackexchange.com/questions/15222/… $\endgroup$ – kepler22b Apr 17 '16 at 13:17
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    $\begingroup$ @kevin: I am a live sound engineer somewhere in the middle between advanced amateur and semi-pro, and I can attest to that. "Normal" speakers pretty much do not understand how to hold a microphone. Even singers often have gross misunderstandings about the physics of a directional microphone. Rappers are the worst, by far. Bottom line: pretty much nobody knows how to hold a microphone. $\endgroup$ – Jörg W Mittag Apr 17 '16 at 14:38
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Many pilots prefer to use their headset boom mic or hand mic instead of the dedicated interphone handset for PA announcements.

I don't know why, but I know from personal experience that the dedicated interphone handset has much better PA readability.

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    $\begingroup$ That doesn't really explain why (supposedly) the announcements are worse than pilots messages with ATC. I doubt the microphone bandwidth is different (the radio channel yes, but not the microphone). $\endgroup$ – mins Apr 17 '16 at 16:11
  • $\begingroup$ Sorry, I don't have any knowledge as to why the ATC microphone does not work as we'll as the dedicated interphone handset. $\endgroup$ – Mike Sowsun Apr 17 '16 at 16:34
  • $\begingroup$ Anyway, this question has already been answered here: aviation.stackexchange.com/questions/15222/… $\endgroup$ – kepler22b Apr 17 '16 at 16:52

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