How does Apple's mobile phone convert the recording into text?

You can try this method, I hope it will help you.

Step 1: Select the option on the left to convert speech into text.

Step 2, add the voice file to be converted.

The third step is to select the type of sound.

Step four, you can choose the voice format.

Step 5, customize the output location.

Step 6: After setting, you can click Start Conversion.