Date of Completion


Document Type


Degree Name

Bachelor of Science in Speech Language Pathology


caffeine intake, voice quality


The objective of this undergraduate thesis is to determine the effects of caffeine in an adultǯs voice. In order to do so, a systematic review was conducted to be able to identify, evaluate, and summarize the findings of all relevant individual studies (Gopalakrishnan & Ganeshkumar, 2013) and to deliver a thorough summary of all the available primary research in response to the question of what effects caffeine has on voice (Clarke, 2011). This systematic review utilized a comprehensive search strategy and search criteria adapted from PRISMA (2020) to obtain relevant studies to this systematic review. Moreover, the inclusion and exclusion criteria was applied to every stage. Throughout the data gathering and data analysis process, the research group had three people cross check separately by applying the interrater reliability to ensure the consistent reliability of data gathering. Four studies were deemed eligible to appraisal after the data gathering process, and were appraised using the Newcastle Ottawa Quality Assessment Scale for risk of bias. The outcomes and results of this systematic review were based on the selected studiesǯ assessments of structural integrity, acoustic characteristics, aerodynamics, and perceptual voice characteristics. Overall, it was seen in the systematic analysis of the studies that caffeine does not have an effect on an adultǯs voice in terms of the aforementioned areas. However, the appraisals of the studies showed that there were risks of biases, and all studies exhibited methodological limitations thus affecting the overall reliability of the results gathered in this systematic review.

First Advisor

Larissa Christia F. Adique, CSP-PASP