The testings probably happened over the span of some years, not just one specific time.  So we could definitely make it work so Solomon was a young tot or something when he got tested on.  Maybe he remembers and thinks they're just imagined though.  His family wouldn't know that he was tested on though.  They would've been told some sort of lie.  Actually, he could have went to "specialists" for hearing, who turned out to be government agents and him and his family never found out.

Sorry for that rambling, just woke up. XD