Lowpass filter for ADC

[tuanvoi]

Hi all,
Could you please confirm that for a digital signal(this signal was ADC from analog voice signal), if I want to convert this digital signal back to analog, do I need to use a lowpass filter or any kind of filter to get the analog one and what range of the LPF? Thank you
Tom

 

[audioguru]

Men's voices go lower than 200Hz and consonants sounds in speech go much higher than only 3400Hz.

An ADC produces a stepped digital output that is full of harmonics. You can hear the harmonics as high frequency buzzing sounds so they must be filtered out.

A CD player has a 44.1kHz sampling rate and a very sharp lowpass filter that attenuates everything above 22kHz.