I'm having this problem and I don't understand how to solve it, I've seen it happen to other people but I still don't understand how to do it
$ dsd -i /dev/dsp -o /dev/dsp -fn
Digital Speech Decoder 1.7.0-dev (build:HEAD-HASH-NOTFOUND)
mbelib version 1.3.0
Enabling only GFSK modulation optimizations.
Decoding only NXDN 9600 baud frames.
Audio In/Out Device: /dev/dsp

Total audio errors: 0
Total header errors: 0
Total irrecoverable header errors: 0

+P25 BER estimate: 0.00%
-P25 BER estimate: 0.00%

Exiting.