Block type - 3 SILENCE BLOCK.

This type of sub-block represents a silence period of the voice data.

The length of silence period (PERIOD) is stored after the BLKLEN.
The value in it is one less than the silence period.

The sampling Rate (SR) is defined as above.

The BLKLEN for This BLKTYPE is fixed at 3.

        ┌──────┬──────┬────────┬──────┬─────┬─────┬────────────┐
        │  03  │      │ BLKLEN │      │   PERIOD  │     SR     │
        └──────┴──────┴────────┴──────┴─────┴─────┴────────────┛