Validate the Efficacy and the Safety of the Keikku Electronic Stethoscope for Its Indication and Intended Purpose, Under the Intended Conditions of Use.

The intervention is a digital stethoscope system comprising a handheld device with a micro-electromechanical system (MEMS) sensor and a Bluetooth Low Energy (BLE) connection to a mobile application (Keikku Mobile App) installed on an iOS or Android smartphone. The device captures auscultation sounds from standard precordial locations (mitral, tricuspid, aortic, and pulmonary), transmits them in real time to the mobile application, and stores the recordings on a secure, GDPR-compliant cloud server. The device does not interpret sounds. Each auscultation lasts 15 seconds per site. Physicians use Bluetooth headphones to listen during recording. The application allows for annotation and review of sound data. The intervention is administered once per participant during a single study visit, immediately followed by a comparator auscultation using a conventional analog stethoscope by a second blinded physician.