# Quantization of analog sound signals

I am using Librosa to detect pitch in a guitar audio signal. I have very little background in signal processing, and I was quite confused with the distinction between analog - digital signals and continuous-time - discrete-time signals.

I am aware that, when I load an audio file in Librosa like this:

y, sr = librosa.load(filename, sr=11025)


I convert the signal to discrete-time. I think that's true as otherwise I wouldn't need to provide an sr.

However, is the signal digital or analog? I see that the analog signal is defined as:

A signal whose amplitude can take on any value in a continuous range

So when does the conversion from analog to digital happen? Or am I working with analog signals?

• See dsp.stackexchange.com/questions/19830/… and many other related questions on this site. – MBaz May 22 '17 at 19:25
• I understand the difference between those. However, the signal with which I am working, is it digital or analog? Is it quantized when I call load or when it is recorded with a microphone? – pavlos163 May 22 '17 at 20:08