Sound cron job delayed while VLC running

[Roger Price <debian@rogerprice.org>]

For nearly 20 years, I have had a cron job in which a dog (yes, it's Biff) barks 
the hours.  The lines in /etc/crontab are

   0   0,12  * * *  rprice /mnt/home/rprice/bark/bark.sh 12
   ...
   0  11,23  * * *  rprice /mnt/home/rprice/bark/bark.sh 11

In the bark.sh script, the sound is produced by sox command

   /usr/bin/play -q hour12.au

I have now migrated to Debian stretch but would still like to hear Biff barking 
the hours.  The cron job works well as long as VLC is not running.  But while 
VLC runs, the cron job waits.  When VLC has finished, I hear the barking.  Is 
there some way of having the barking while VLC plays?

I can see nothing in VLC configuration file ~rprice/.config/vlc/vlcrc which 
prevents others from accessing the sound card at the same time.

Roger