Im in a computing class and the subject of ADC came up, and we are wondering why such a bizarre figure as 44.1Khz was used for CDs.

Any ideas?

Read post#18.

http://www.hydrogenaudio.org/forums/index....2466#entry23904

basically we can hear up to 20KHz, the need min sample rate to reproduce that frecuency is 40Ksamples per second (one sample up other down, square pulse train of 20Khz). Do you find it low?

Thanks paladin, I actually found that thread a while after posting, and showed it to my lecturer, but didnt have time to follow up my post here. Rox, your point is valid but I wanted to know why they chose 44.1 and not 40 or 45 or something!

mm
don´t know why 44100 was chossen... maybe because it is divisible by 50 and 60?

maybe the line frecuency is the reference for some old machines so they divide/multiply it to get to the desired frecuency. Being it dibisible by 60 and 50 hz is very suspicius for me.

Because the part to implement 44.1 was readily available and cheaper then refabricating something new, would be my reasoning. Same for most engineering devices .

See the link paladin posted above......

50 Hz is used for PAL systems.
60 (59.994) Hz is used for NTSC systems.


Humans can hear up to ~20 kHz --> sampling freq of 40kHz at minimum. Add 10% to get 44kHz at a minimum (for those people who can hear above 20kHz)

44100 Hz is the next number divisible by 300 (Least Common Multiple of 50 and 60)

Now the question is why did PAL use 50 Hz and NTSC use 60 Hz??? That probably has to do with the line frequency.

It must also be taken into account that the number of lines per frame (the resolution) is different between PAL and NTSC. Why they are different I dont know, but why does Europe use Metric and the US use Imperial? Why do countries use different currencies and speak different languages?

You get the picture!