The aim of this study is to examine the effects of binaural beat music played during spinal anesthesia knee arthroplasty on anxiety, pain and cortisol levels. The study was planned as a randomized controlled experimental design study. The hypotheses of the study are as follows; * Binaural beat music played during spinal anesthesia knee arthroplasty has no effect on anxiety. * Binaural beat music played during spinal anesthesia knee arthroplasty has an effect on anxiety. * Binaural beat music played during spinal anesthesia knee arthroplasty has no effect on pain levels. * Binaural beat music played during spinal anesthesia knee arthroplasty has an effect on pain levels. * Binaural beat music played during spinal anesthesia knee arthroplasty has no effect on cortisol levels. * Binaural beat music played during spinal anesthesia knee arthroplasty has an effect on cortisol levels. A sample group will be formed with 20 patients in the intervention group and 20 patients in the control group. Binaural beat music will be played in the intervention group during the surgical procedure, and routine interventions will be applied to the control group. Data collection in the intervention group is as follows; * Patients will be interviewed in the surgery clinic before surgery and the descriptive characteristics form and the State Anxiety Inventory Form will be filled out. * The 1st measurement of hemodynamic data will be recorded immediately before the surgery * A musical concert will be started as soon as the surgery begins * The musical concert will end when the surgery ends * The 2nd measurement will be recorded immediately after the surgery ends * In the post-surgery collection unit, the State Anxiety Inventory Form and the Visual Comparison Scale will be used, and a blood sample will be taken to determine cortisol values. The control group data collection methods are as follows; * Patients will be interviewed in the surgical clinic before surgery and the descriptive characteristics form and the State Anxiety Inventory Form will be filled in * The first measurement of hemodynamic data will be recorded immediately before the surgical procedure * The second measurement will be recorded immediately after the surgical procedure is completed * Blood samples will be taken in the post-surgical recovery unit to determine the State Anxiety Inventory Form, Visual Comparison Scale and cortisol values.