DOI: 10.5281/zenodo.17390395
title: The Sound of Sleepiness: A 24-hour sleep deprivation experiment, examining the relationship between Acoustic Vowel Space and sleepiness in sleep-deprived, Danish-speaking individuals.
title: A 24-hour sleep deprivation experiment, examining the relationship between Acoustic Vowel Space and sleepiness in sleep-deprived, Danish-speaking individuals.

description: This is a complete dataset for the study The Sound of Sleepines: A 24-hour sleep deprivation experiment, examining the relationship between Acoustic Vowel Space and sleepiness in sleep-deprived, Danish-speaking individuals, published in the Journal of Language Works, 10(2), ISSN: 2446-0591, 2025.

The dataset includes:



measureF1F2F3F4inxxx.praat: 4 Praat Scripts for output of the first four formants of the Danish corner vowels /i u æ a/, by Associate Professor at the University of Copenhagen, Nicolai Phrarao (2023).

Huskespil_xxx: CSS, HTML and JS files for four seperate memory tests.

reaction_time_game: CSS, HTML and JS files for the reaction time test.

Whisper_in_Praat_v0.8.2: Whisper AI script for Praat written by PhD Gert Foget Hansen. Newer versions and other required documents can be found at DOI:10.13140/RG.2.2.24093.93925.

All Statistical Data: A .docx of all statistical data, which includes all 12 individual AVS-plots, and all statistical models of both significant and non-significants correlations.



Both AVS-plots and statistical models are included as individual .png files, eg. AVS_Plot_T1_EN and plot_1_EN



VSA of all Participants: An .svg image of all 12 AVS-plots combined.

All Non-Phonetic Participant Data ANONYMOUS: A comprehensive .xlsx of all non-phonetic data collected during the study, including exact wake-up time, exact time of each data-collection, usual number of wakefull hours, usual bedtime, self-assesment scores, reaction-times, and memory-game results.  

All Phonetic Data: A comprehensive list of all phonetic data collected for every token, including at which wakeful hour it was collected, which participant it was collected from, F1 and F2 mean measuremnets, and duration in milliseconds. 

Consent Form: The consent form which all participants were required to read and sign prior to participation. 

Distribution of Vowel Tokens: A .png file showing the distrubution of tokens per data collection, in number of tokens as a function of vowel duration. 

Elicitation Materials: A .docx of all 8 drawings used as elicitation material.

Target Words: A comprehensive list of all 61 target-words used in the final study, each including a long, stressed Danish corner vowel (/i u æ a/) without stød. The seleted target words did not include vowel sounds affected by r-coloring, velar transitions, or coarticulation with the Danish soft d.

Questionnaire: All participants were required to complete a questionnaire in the weeks leading up to the experiment. The questionnaire gathered data on participants’ typical bedtime, average number of wakeful hours, and habitual use of nicotine and caffeine. It also included exclusionary questions regarding age, first language (L1), region of origin, potential sleep disorders, and the use of sleep medications or central nervous system (CNS) stimulants.


 
description: This study investigates the impact of short-term sleep deprivation on Acoustic Vowel Space (AVS), hypothesizing that Vowel Space Area (VSA) will shrink, with a more pronounced correlation with sleepiness, rather than simply the duration of wakefulness. Sleepiness-levels were assessed using the Karolinska Sleepiness Scale, reaction time measurements, and performance in a memory task. Phonetic data were collected through semi-spontaneous speech tasks, using picture descriptions recorded in a controlled sound studio environment.

Twelve native Danish speakers (aged 20–30) were monitored over a 24-hour period, with data collected at six-hour intervals. Variables such as individual sleep habits, substance use, and environmental influences were controlled for to ensure reliable results.

On average, VSA decreased by 14.23% after 24 hours of wakefulness compared to baseline (after 6 wakeful hours), with 11 of 12 participants showing an overall reduction. Significant correlations were found between normalized VSA and two sleepiness-markers: reaction time (p = 0.010) and self-reported sleepiness (p = 0.002), but not with memory-based markers. Notably, VSA correlated more strongly with hours awake past participants' usual bedtime (p = 0.000943) than with total hours awake (p = 0.0014), suggesting a sleepiness-related effect rather than one driven by vocal fatigue.