While looking for one to set as my ringtone, I became interested in the history of the cabin chime - the "bing-bong" noise heard on practically every commercial airliner today. I've found tons of downloads for the sound itself and a few posts by pilots and cabin crew on what different chimes or sequences of chimes mean, but nothing on its origin. Anyone?
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$\begingroup$ I just happened to read this a few minutes ago from a flight attendant's blog: "The only thing you have to fear is "the triple high-low chime." That's the captain telling the flight attendants to prepare for an emergency." $\endgroup$– TomMcWSep 29, 2016 at 19:47
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4$\begingroup$ Huh. It varies by airline - United, Continental, and another airline use 5 for emergencies, but Delta uses 3 or 5 for normal landings, and Northwest and another one used 4 for "brace for impact." $\endgroup$– MattSep 29, 2016 at 19:58
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1$\begingroup$ Related $\endgroup$– DaveSep 29, 2016 at 20:56
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I can't definitively identify the true origin of the chimes; but the earliest reference to them I can find is in:
ARINC Characteristic 715-3 Airborne Passenger Address Amplifier (PA AMP)
This standard describes the characteristics of a PA AMP designed for installation in commercial aircraft. Its function is to amplify control voice, music and internally generated chime audio signals to drive the aircraft cabin loudspeaker system.
The original ARINC 715 was published in 1978.
The standard they defined is in section 3.4 of the document:
3.4 Chimes
The PA Amplifier equipment should include a chime generator capable of providing two tones in the four remote controlled sequences that may be deployed through either the auxiliary or main amplifier utilizing aircraft strapping. Internal controls shall be provided to adjust the individual tone levels for balancing the related outputs.
3.4.1 Tone Frequencies
The high tone should be 587 Hz (musical Note D) and the low tone should be 494 Hz (Musical Note B) signals of a pleasant sounding musical nature.
3.4.2 Tone Harmonics
The chime tone harmonics should be minimized with the second harmonic level at least 30 dB below that of the fundamental and each succeeding harmonic should be a further 3 dB below the preceding harmonic.
3.4.3 Tone Decay
The single high and low tone levels should decay to a level 30 ±6 dB below the peak level within 900 milliseconds from the peak. The second tone of the high/low combination should begin 900 ± 100 milliseconds after the peak of the first tone.
3.4.4 Sequence Control
Five tone sequence control lines should be provided to actuate individual or two tone sequences as follows:
a. Passenger Call (High Tone)
b. Attendant Call (High/Low Tone)
c. Attendant Emergency Call (High/Low Tone Repeated Three Times)
d. Seat Belt Sign (Low Tone)
e. Smoking Sign (Low Tone)
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1$\begingroup$ That's a pretty exacting standard! It certainly explains why they all sound the same regardless of the aircraft and avionics manufacturers. $\endgroup$– MattOct 26, 2016 at 18:12
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3$\begingroup$ Love how an otherwise quite technical specification requires the tones to be "of a pleasant sounding musical nature". $\endgroup$ Jun 28, 2022 at 7:50