The noise pollution caused by anthropogenic activities in the aquatic environment negatively affects aquatic organisms like mammals, fish, crustaceans, and even plankton, which are important for the aquatic ecosystem. This study was conducted to examine the effect of lethal and sub-lethal effects of high-frequency sound exposure on Daphnia magna aiming to obtain more detailed scientific information. For this purpose, a total of 150 gynandromorphic daphnids were randomly selected, sorted equally into 440 Hz, 432 Hz, and control groups, and high-frequency sounds were applied in aquatic conditions. During the 35-day trial period, the heartbeats, and egg numbers were counted whereas the survival rates were recorded. The results showed that the high-frequency sound exposure immediately showed its detrimental effect on heartbeats after a short adaptation period in the 440 Hz group and the average values decreased to half of the normal values. In the 432 Hz group, heartbeats first increased, and this level was maintained for a while, but then a significant decrease was observed. Regarding the egg numbers, an increasing trend was observed in the 432 Hz group until the 5th measurement period which resulted in a sharp decrease. In the 440 Hz group, lower values with almost no increase were recorded, except for the first measurement period, but no eggs were found in the 5th measurement. Interestingly, while no death was noted during the measurement periods, no living daphnia was observed in the 440 Hz group within 2 weeks during the non-measurement period. As a result, it was understood that Daphnia perceives the vibrations produced by high-frequency sound in the aquatic environment as a stressor and cannot cope with its detrimental effects after a certain time depending on intensity and duration. While the 440 Hz frequency noise caused infertility, the 432 Hz frequency noise resulted in lower egg numbers and heartbeats.