ASA 2009 Casebook Play Confusion

[Steve M]

Originally Posted by tcannizzo

So, if the OC yelled "GO", but then the DC yelled, "DEAD BALL..." causing the runner to stop and then be tagged out, is the runner supposed to know the difference between the DC and Umpire's voice?

Stop and think about that for a minute, Tony.
In the casebook, the defense - player and/or coach - yells an instruction to the runner that the runner's own base coach normally yells. The runner is expected to know their coach's voice.
In your variation - it's entirely different - you have the defense yelling something that an umpire would normally yell. I do not see the casebook as saying that.