To cast your android phone audio to your computer, you can follow the steps below:
Step 1. To start with, you need to find an aux cable and plug it into the blue jack in the back of your desktop computer. Then plug the other end to your android device.
If you're using the laptop, you need to make use of an external sound card and make it connect with your android phone via the aux cable.
Step 2. Open your computer and right-click the sound icon in the bottom-right corner and click Open Volume Mixer.
Step 3. Then, click on System Sounds and a new window will appear on which you need to find the Recording tab. Go to Line In. right-click on it, and then tick Enable.
Step 4. Right-click Line In again and then choose Properties. A new window pops up, and you tick the box ahead of Listen to this device. Then, click OK. Now, you can cast the Android audio to your computer.