New York's main contract, light sweet crude for delivery in August, shed 26 cents to $88.96 a barrel and Brent North Sea crude for September delivery 60 cents to $103.40.
Crude markets were discouraged by Bernanke's address to Congress on Tuesday, which contained no clear indication of a new round of quantitative easing or any additional Fed action to jumpstart the US economy, analysts said.
"While a QE3 announcement was never really on the cards, markets were hoping to get a clearer insight into what sort of conditions would prompt more Fed intervention," IG Markets said in a report.
"Sadly all Bernanke did was to repeat what he's said previously and reiterate his frustrations about the US economy's slow recovery. Not comments really worth getting out of bed for."
Bernanke said the US economy might be heading for even slower growth than the two percent it recorded in the first quarter, but reiterated that the Fed was prepared to react should it deteriorate.