Caffeine is a widely consumed substance worldwide and is often used to increase alertness and improve cognitive functions. Caffeine stimulates brain activity by binding to adenosine receptors, which increases alertness instead of sleepiness. Studies on the effects of caffeine on cognitive functions have shown that it improves basic cognitive functions such as attention, reaction time, and alertness, while a less pronounced effect is seen on sensory functions such as vision and hearing. However, no study has been found investigating the effect of caffeine consumption on understanding speech in noise. Understanding speech in noise is a skill that includes not only auditory functions but also cognitive functions. This skill is affected by cognitive elements such as selective attention and executive functions. In this context, it is thought that this study, which aims to examine the relationship between caffeine and understanding speech in noise, will contribute to the literature. 60 participants between the ages of 18-30 will be included in this study. Participants will consist of individuals without hearing loss (SSO\<25 dB nHL), no history of neurological or psychological disorders, non-smokers, and those who do not use ototoxic drugs. Participants will be randomly divided into a placebo group that consumes decaffeinated coffee and a study group that consumes coffee containing 300 mg caffeine. The Turkish Matrix Test will be administered 30 minutes after coffee consumption. In addition, participants will be asked to keep a caffeine diary for one week to determine their daily caffeine consumption and will be asked to fill out the Caffeine Use Disorder Scale. Thus, they will be divided into low and high caffeine consumption groups and their speech understanding skills in noise will be compared.