The “Morning Voice”: The Effect of 24 Hours of Sleep Deprivation on Vocal Parameters of Young Adults

Michal Icht, Gil Zukerman, Shir Hershkovich, Tal Laor, Yuval Heled, Nir Fink, Leah Fostick

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Fatigue following sleep deprivation adversely affects various aspects of human performance. It also induces recognizable voice changes, but the literature is inconsistent regarding their nature. The current study used acoustical analyses to assess the effect of 24 hours of sleep deprivation on vocal parameters of young adults. Forty-seven participants (23 females and 24 males) were tested after nocturnal sleep and after 24 hours of sleep deprivation. Different voice samples were recorded (sustained phonation, words, and sentences) and analyzed for fundamental frequency (F0, in Hz), vocal intensity (in dB), harmonic-noise ratio (HNR, in dB), jitter, and shimmer (in %). The main finding was significantly higher HNR values following sleep deprivation than nocturnal sleep for females, across all voice samples. The HNR is a measure of the degree of acoustic periodicity, or the amount of noise compared to the harmonic quality present in the voice. As its values are higher, the voice quality is perceptually better. The current results indicate that females had a significantly higher ratio of vocal harmonics compared to vocal noise when they were sleep deprived. In contrast, following nocturnal sleep, the ratio of vocal harmonics compared to vocal noise was lower, which means the voice quality was poorer. This may explain the common perceptual impressions of decreased voice quality after sleep, which may be more pronounced in females.

Original languageEnglish
Pages (from-to)489.e1-489.e9
JournalJournal of Voice
Issue number3
StatePublished - May 2020
Externally publishedYes

Bibliographical note

Funding Information:
Funding: Research reported in this publication was supported by the Israel Defense Forces (IDF) Medical Corps and Directorate of Defense Research & Development, Israeli Ministry of Defense (IMOD DDR&D, Grant No. RA1500000862).

Publisher Copyright:
© 2018 The Voice Foundation


  • Acoustical analysis
  • Fatigue
  • Harmonics-noise ratio
  • Sleep deprivation
  • Voice quality


Dive into the research topics of 'The “Morning Voice”: The Effect of 24 Hours of Sleep Deprivation on Vocal Parameters of Young Adults'. Together they form a unique fingerprint.

Cite this