Firstly, we need to make sure you have installed the latest version of the program.
You can download the latest version from our official website: https://www.aiseesoft.com/
Besides, we need to collect some more information about the original file.
1. Please make sure the source file can play well without any sound problem on your computer before conversion.
2. Please try to preview the source file in the program and find out if the sound can play well.
3. Then please tell us how did you get the original video, have you used some special tools to get it?
4 Please confirm that you have adjusted the Audio Volume before conversion.
5 Please try other output format to check if there still the same problem.
If the above suggestion cannot solve your problem, you can contact our Support Team with a clip of your original video. They will check the problem soon.