Digital Speech Standard (DSS) is a proprietary compressed digital audio file format defined by the International Voice Association, a co-operative venture by Olympus, Philips and Grundig. DSS was originally developed in 1994 by Grundig with the University of Nuremberg. In 1997, the digital speech standard was released, which was based on the previous codec. It is commonly used on digital dictation recorders. Modern phycoacoustical codecs that perform nearly as well at only slightly higher bitrates have led to this speech coding standard being less used in modern voice recording equipment.

OGA is an audio extension for OGG file and it was developed by Xiph.Org Foundation. OGG is an open container format designed for streaming and may contain independent video, text and audio files. To open OGA, you need either to install an appropriate software like Vorbis, or to convert the file to a more common format.