To stream music from your computer to WeChat voice, you can follow the steps below:

1. Open the music player software and select the desired music file.

2. Press the "Windows key G" at the same time to open the game bar that comes with the Windows system.

3. In the game bar, click the "Record" button to start recording your screen and audio.

4. Open WeChat on your computer and enter the chat window where you want to send voice.

5. Play the music you want to send and click the voice button on the WeChat chat window to start recording the voice.

6. When the music has finished playing, click the voice button on the WeChat chat window to end the voice recording.

7. In the WeChat chat window, you will see the voice you just recorded and can send it to the other party.