VL-3 Training Study

Inclusion Criteria: * Male or female ≥18 and ≤ 85 years of age at the Baseline Visit. * Written informed consent obtained from subject or subject's legal representative and ability for subject to comply with the requirements of the study. * A minimum of 30% of the data will be derived from male subjects; and a minimum of 30% of the data will be derived from female subjects. * A minimum of 50 participants will have dark skin types, as defined by the Fitzpatrick Skin Type classification V or VI. * Also, at least 10 participants should exhibit finger calluses, found typically on individuals who play stringed instruments frequently. Exclusion Criteria: * 1\. Pregnant and/or breastfeeding. 2. Presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the patient or the quality of the data. 3\. Are unable or unwilling to undergo all assessments associated with the study. 4\. Have a history of poor quality or difficulty performing auscultation measurements. 5\. Subjects shall be excluded if the Korotkoff sound \[fifth phase (K5)\] is not audible 6. Subjects with vascular implants in the arm of measurement, such as those used for dialysis 7. Subject suffering from a medical condition prohibiting blood flow occlusion in either arms. 8\. Pre-existing conditions that may interfere with the accuracy or interpretation of auscultatory readings, such as aortic coarctation, arterial-venous malformation, occlusive arterial disease, or the presence of an antecubital bruit. 9\. Subjects who have known allergies to nitroglycerin (for subjects undergoing the nitroglycerin challenge). 10\. Subjects who have taken short acting nitroglycerin within 4 hours of the scheduled study. Such studies will be deferred for at least 4 hours. 11\. Subjects who have taken long acting nitroglycerin within 8 hours of the scheduled study. Such studies will be deferred for at least 8 hours. 12\. Subjects with pericardial tamponade, restrictive cardiomyopathy, or constrictive pericarditis, or cardiac output is dependent upon venous return