Purpose: Degraded speech intelligibility in background noise is a common complaint of listeners with hearing loss. The purpose of the current study is to explore whether 2nd formant (F2) enhancement improves speech perception in noise for older listeners with hearing impairment (HI) and normal hearing (NH). Method: Target words (e.g., color and digit) were selected and presented based on the paradigm of the coordinate response measure corpus. Speech recognition thresholds with original and F2- enhanced speech in 2- and 6-talker babble were examined for older listeners with NH and HI. Results: The thresholds for both the NH and HI groups improved for enhanced speech signals primarily in 2-talker babble, but not in 6-talker babble. The F2 enhancement benefits did not correlate significantly with listeners' age and their average hearing thresholds in most listening conditions. However, speech intelligibility index values increased significantly with F2 enhancement in babble for listeners with HI, but not for NH listeners. Conclusions: Speech sounds with F2 enhancement may improve listeners' speech perception in 2-talker babble, possibly due to a greater amount of speech information available in temporally modulated noise or a better capacity to separate speech signals from background babble.