Detrimental Effects of Time-Compression and Background Noise on Memory and Neural Encoding: Implications for Online Learning Environments

Author: Mako Ikeda

Field of Study: Science, Technology, Engineering, and/or Math

Program Affiliation: Summer Scholars and Artists Program (SSAP)

Faculty Mentors: Sung Joo Lim

Easel: 64

Timeslot: Midday

Abstract: With the rise of online education, students often prefer accelerated playback speeds. Although speech perception remains stable at faster rates, memory recall tends to decline—especially in noisy environments. It remains unclear whether this decline results from increased attentional demands or impaired encoding of fast speech. This study used EEG to examine how the brain processes time-compressed speech in quiet and noisy conditions. Participants listened to speech at three rates (1.0x, 1.5x, 2.0x). Neural tracking analysis measured how well the brain followed speech’s temporal structure. Memory performance declined with faster speech and background noise, but no interaction was found. Neural tracking showed a significant effect of noise—tracking was reduced in noisy conditions—while compression rate had no significant effect. The noise-related decline in both suggests that memory suffers when the brain struggles to track speech. This implies noise disrupts stable speech representations more than it taxes attention.