Ten-year US Treasury yields rose 1.5 basis points to 1.49 percent, with some in the market hoping a weak run of US data could prompt Bernanke to hint at more stimulus - which is generally favorable for riskier assets like equities at the expense of safe-haven bonds.
Ten-year US yields matched historical lows of 1.44 percent in the previous session after data showed a surprise drop in retail sales in June - the latest evidence that the world's largest economy is slowing.
Expectations that Bernanke would signal something specific were vulnerable to disappointment, according to some analysts. They said it was more likely that, so soon after the central bank extended its "Operation Twist", the Fed chief would reiterate the bank was open to doing more but that more evidence of weakness was needed first.
"There are still some people that are betting on more and I think it's most likely that they are going to be disappointed," Philip Marey, strategist at Rabobank said.
Minutes from the central bank's June meeting showed recently that the Fed was open to buying more Treasury bonds to stimulate the economy, but the recovery might need to weaken for a consensus to build. Last month, it extended Operation Twist - selling short-term bonds to buy long-term ones in a bid to keep long-term interest rates low.
Thirty-year government bond yields rose 1.4 bps to 2.57 percent, while short-dated yields were broadly steady.
Investors will also look to industrial output data later in the session for fresh insight into the health of the US economy. Recent releases have painted a gloomy picture, with data on Monday showing US retail sales fell for the third straight month, the longest run of consecutive drops since 2008 when the country was mired in recession.
Against this backdrop, and with the euro zone debt crisis providing a steady stream of safe-haven appetite, one trader said 10-year yields should hit new record lows.