Would someone explain something to me regarding the interest...

Would someone explain something to me regarding the interest rate fear. Are the words of the US and Aus federal reserve chairs not to be completely trusted and that is the reason for the concerns at the moment regarding interest rates and a possible upping of them before we have been told it would happen? I understand the part the bond yields normally play, but they seem a moot point to be honest in reference to their effect on interest rates over the next few years if we're to believe what we're told.

They have said very firmly 3 years minimum until they raise them and the words of Jeremy Powell seem to have a massive impact on the stock market when he delivers his reports. So wouldn't it be assumed then that the chair of the reserve has a high level of integrity? Otherwise why would the market react in such ways to mere words. Because if the chair's office was known to spew lies, then would the market not of moved to a fact-react situation a long time ago, rather than hang off what they say?