ELEMENT_INFO_ST

length
The length in bytes of a buffer required to export the data in the voice elements to a standard format, using 8-bit samples at 8,000 Hz.
compression_type
The compression type of the voice elements. Possible values are COMPRESSED_VOICE or UNCOMPRESSED_VOICE.
format
The format of the voice elements. Possible values are FORMAT_ALAW or FORMAT_ULAW. if the compression type is COMPRESSED_VOICE, this value is ignored.
volume_level
The maximum volume level of the voice elements, in dBm.