# How many beats per second can human hearing distinguish?

**URL:** <https://boards.straightdope.com/t/how-many-beats-per-second-can-human-hearing-distinguish/817865>\
**Category:** Factual Questions\
**Created:** [July 13, 2018, 10:07pm UTC](https://boards.straightdope.com/t/how-many-beats-per-second-can-human-hearing-distinguish/817865 "2018-07-13T22:07:47Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![MichaelEmouse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/michaelemouse/32/101_2.png) [@MichaelEmouse](https://boards.straightdope.com/u/MichaelEmouse)\
**Post date:** [July 13, 2018, 10:07pm UTC](https://boards.straightdope.com/t/how-many-beats-per-second-can-human-hearing-distinguish/817865/1 "2018-07-13T22:07:47Z")

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Let’s say I play the same sound several times per second at equidistant intervals. How many times can I play it per second until I’m no longer able to distinguish that they’re discrete sounds and they start blending together?

Second, if I were to analyse the sound I play, would I find that it only seems continuous because it’s composed of its own repetitions which are too rapid for me to resolve? Is it turtles all the way down?

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**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\
**Post date:** [July 13, 2018, 10:21pm UTC](https://boards.straightdope.com/t/how-many-beats-per-second-can-human-hearing-distinguish/817865/2 "2018-07-13T22:21:32Z")

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The human brain seems to top out at both vision and sound somewhere around 1/10th to 1/15th of a second, with a bit of variation between individuals. Sounds that occur less than 1/15th of a second apart seem simultaneous, just as images that change faster than 1/15th of a second seem like motion and not individual images.

TV and movies use a slightly faster frame rate than that since even though 10 to 15 frames per second is “good enough” for most people, your brain still perceives a bit of flicker. Getting up above 30 frames per second gets rid of the flicker.

Similarly, at about 10 to 15 beats per second, your sounds will blend together.

I don’t understand your second question.

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**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\
**Post date:** [July 13, 2018, 10:42pm UTC](https://boards.straightdope.com/t/how-many-beats-per-second-can-human-hearing-distinguish/817865/3 "2018-07-13T22:42:12Z")

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I know precious little about acoustics or phonology; but I believe you would benefit from reading the works of Herrman von Helmholtz, who actually made these things a science.

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**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\
**Post date:** [July 13, 2018, 11:40pm UTC](https://boards.straightdope.com/t/how-many-beats-per-second-can-human-hearing-distinguish/817865/4 "2018-07-13T23:40:52Z")

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Humans can usually hear sounds between about 20-20000 Hz, so once in that range you should be hearing a distinct pitch; the record, under ideal laboratory conditions, for hearing a musical tone is 12 Hz. There is also a phenomenon called [temporal masking](https://ccrma.stanford.edu/~bosse/proj/node21.html) where a strong sound causes you not to perceive a weaker sound for a short time before (20 ms) or after (up to 200 ms) it.

If you analyse an arbitrary sound sample, for example with a Fourier transform, it is true that it is composed of a spectrum of frequencies, but it is subject to complicated psychoacoustics when you hear it. But, yes, physically you can regard it as a combination of repetitive sine waves.