Aortic valve: Right sternal border at second intercostal space Pulmonic valve: Left sternal border at second intercostal space Tricuspid valve: Lower left sternal border in 4th intercostal space Mitral valve: Fifth intercostal space medial to mid-clavicular line. Reference: https://journals.rcni.com/nursing-standard/how-to-auscultate-for-heart-sounds-in-adults-ns.2017.e10965