The present work examined factors affecting the intelligibility of high-intensity-level-based speech. Mandarin sentences were processed to contain only high-intensity segments confined by a 5-dB selected intensity range (SIR), with other segments replaced by noise. The processed stimuli were presented to normal-hearing listeners to recognize. The greatest intensity density occurred in the SIR with an upper boundary 3 dB below the peak intensity level, and this SIR yielded the highest intelligibility score in quiet. The SIR with the upper boundary at the peak intensity level yielded better intelligibility performance under noisy conditions, due largely to the relatively high effective signal-to-noise ratio.