[keithxm23]

Often, I'll come across speakers who just speak slowly and listening at 1.5x or 2x barely feels sped-up.

Additionally, the brain tends to adjust to a faster talking speed very quickly. If I'm watching an average-paced person talk and speed them up by 2x, the first couple minutes of listening might be difficult and will require more intent-listening. However, the brain starts processing it as the new normal and it does not feel sped-up anymore. To the extent that if I go back to 1x, it feels like the speaker is way too slow.