Does a more enthusiastic synthetic narrator improve learning from a narrated lesson?

Problem. Whether adding emotional cues to a TTS narrator helps viewers learn. Conditions. Between-subjects online experiment, n = 244 learners at a large Asian university, listening to Amazon Alexa narrating a multimedia lesson on a denial-of-service attack in a neutral, low-, medium- or high-enthusiasm voice. Measured result. Enthusiastic voices did not raise immediate retention or transfer scores over the neutral voice; medium and high voices were perceived as more enthusiastic; low and high enthusiasm lowered intrinsic and extraneous cognitive-load ratings; the medium voice raised positive emotion from baseline; persona ratings did not improve. Failure modes. Strong prosody can add load for non-native listeners (the authors' argument). Limitations. One 2022 voice product, one topic, university students, immediate tests only, no human-voice control, no words-per-minute figures extracted. Inference (labelled): richer TTS expressiveness is not shown to improve retention, so do not justify an expressive narrator by learning gains; judge it by listener load and preference tests (see TTS evaluation items C3-B081-G31-03 and C3-B570-13). Version/date. Accepted 20 Jul 2022. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Single study; the voice (Alexa 2022) is no longer representative of current TTS. The abstract's own wording is used; effect sizes were not extracted. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

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