Is there any way for me to convert pdf/audio files into a searchable text?

You can easily do this on Adobe Acrobat. Follow these steps:

1. Open Adobe Acrobat. Go to the “File” in the drop down menu and select “Open.” Open the desired PDF file that you intend to have indexed and searched and select “Open.” Make sure that the first page displays in the Adobe Acrobat work area.

2. Go to “Tools” on the right and choose the option that says “Recognize Text.”

3. Select PDF Output Style “Searchable Image” and click “OK.”

4. Hit “Save” and save the document once the conversion process is complete. Save the PDF as a new name so you have both new and original documents available.
As a reference, you can also look here:

PDF files that have audio or video files mixed into them cannot be converted to have recognizable text. It is not possible to guarantee an exact reproducibility with embedded objects such as movie or sound.

For a more detailed explanation, refer to: