How to detect if a signal is audio

Question

I have a stream of samples collected from a 12-bit ADC that is connected to a microphone-pre-amplifier bundle. Since the sample is 12 bit, so I can assume the they range from 0-4096 in decimal values. After I shifted it down by 2048 and divide by 2048 to obtain a set of samples with in -1 and +1, I should get a nice waveform that represents the audio stream.

(Up to this point, please correct me if I am wrong.)

What I obtained from that linear mapping is a set of samples "oscillates" around -0.55ish. (Usual audio stream samples oscillates around 0)

I am not exactly sure whether to shift and scale again to obtain a waveform that oscillates around 0, or there is something I am doing wrong with the ADC. In either case, I want to know how to determine if my output is an audio stream or a set of random useless samples. Thank you guys!

Answer 1

DC Offset Or DC Bias is a property present in various types of electronic signals and ADC converters.

"DC blocking" or "DC Removal" eliminates any DC component from the audio signal before being processed removing any signal offset.