440 Hz is also the standard telephone dial tone in the US. | Hacker News

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mediaserf on Oct 24, 2016 | parent | context | favorite | on: The “432 Hz vs. 440 Hz” conspiracy theory

440 Hz is also the standard telephone dial tone in the US.

sp332 on Oct 24, 2016 [–]

Dial tones are a chord of 440 and 350 https://en.wikipedia.org/wiki/Precise_Tone_Plan This follows on from DTMF's use of pairs of tones for signalling. https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_sign...

finnh on Oct 24, 2016 | [–]

I love the scene in Adaptation where a tripping Meryl Streep and Chris Cooper harmonize the dial tone chord while talking on the phone.

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