Resolution and sampling frequency

I want to test what resolution and sampling frequency do to the audio signal by reducing sampling rate and resolution of audio files.

How do I do this?

The information I have gotten is that I should start by reducing sampling rate, since it requires the least programming.

And the follow tips:

matlab example of downsampling:

x_downsamling = x (1: 3: end)% takes out every third sample of x vector.

Remember to low-pass filters before downsampling. Why?

Also remember to change the playback speed when playing the sound.

Bit resolution reduction:

Let's say you have a signal that goes between -1 and 1 y.The floor (y + 1) function will take out an integer that is either 0 or 1 so that it is now reduced to 1 bit resolution.Then remember to scale so that the signal goes between -1 and 1.

For other bite resolutions:

1./N*floor(N.*y+a)-bThen select a, b, N to fit the desired bit resolution ..Feel free to test the function you create on a synthetic signal that goes between -1 and 1. you want a curve that looks like a step.

[Walter Roberson]

Use resample() unless you are required to implement the downsampling "manually"

Signal quantization is only directly available to fixed-point objects using the Fixed Point Toolbox. However it is easy enough to use discretize() followed by using the bin number to look up the "representative" value for that bin.

[Star Strider]

Slight clarification: There are several functions called resample. (This is likely the one you need.)

[Walter Roberson]

Let's say you have a signal that goes between -1 and 1 y.The floor (y + 1) function will take out an integer that is either 0 or 1

y = 1

y = 1

floor(y+1)

ans = 2

2 is neither 0 nor 1. Saying "either 0 or 1" only holds when that "between -1 and 1" is intended to mean "strictly between" and never equal to the bounds. But in signal processing, it is common to get signals that have elements that are exactly -1 or exactly 1