At 0700 AEST on Wednesday, the local currency was trading at 93.71 US cents, up from 93.69 cents on Tuesday.
In her testimony to Congress overnight, Yellen said the Fed could raise its interest rate sooner than expected if the labour market continued to improve more quickly than anticipated.
“The semi-annual testimony to Congress started as usual, and initial indications were that she was her usual downbeat self,” National Australia Bank senior currency strategist Emma Lawson said.
“She noted that if the labour market continued to improve more quickly than expected then they will have to hike earlier and more rapidly than they are expecting.
“The fact is, the labour market is picking up quickly. The data has been better.
“The moves overnight were fairly muted for this speech, but as long as the data continues to show form, then those moves will likely build.”