Investors are eagerly awaiting Federal Reserve Chair Janet Yellen's speech on Tuesday at the Economic Club of New York and one expert expects some clues on when then central bank will hike short-term rates next. 'I would expect some type of verbiage addressing the timing of the next rate hike,' said Scott Wren, senior global equity strategist at Wells Fargo Investment Institute. 'In our opinion, we'll see one [hike] this year.' Wren also said he'll be focused on the year-over-year change in average hourly earnings, which will be released on Friday in conjunction with the March jobs report. TheStreet's Scott Gamm reports from Wall Street.