Files with ss3 file extension can be found as old audio files from Japanese Singer Song Writer program. Most likely used in version 3 of the program.
SS3 file extension - Singer Song Writer audio data
What is ss3 file? How to open ss3 files?
File type specification:
The ss3 file extension is mainly related to Singer Song Writer, a Japanese audio recording and music creation software from INTERNET Co ., Ltd.
SS3 is probably audio file type created in version 3 of the program, so rather old.