Validate Playback

Use the commands below to validate the playback function.

To play a 10-second sound track in the sample rate of 16 KHz:
```
# aplay -Dhw:0,1 -f S32_LE -r16000 -t wav sound_32b_16k.wav
```
To play a 10-second sound track in the sample rate of 44.1 KHz:
```
# arecord -Dhw:0,1 -f S32_LE -r44100 -t wav sound_32b_44100.wav
```