Abstract Pneumonia has been the leading cause of death among children under the age of five in subSaharan Africa, killing more children than the number of children dying from HIV/AIDS. The current methods of diagnosing pneumonia are limited by poor sensitivity and accuracy and they are also expensive. In this project, a low-cost biomedical device was designed and developed to improve the accuracy in diagnosing pneumonia hence assisting in correct prescription of drugs to children. Sounds waves were transmitted from a surface exciter which was connected to an Arduino-powered circuit. The sounds waves were allowed to pass through one side of a lung phantom made of sponge and were detected on the other side using an electronic stethoscope. 4 dry sponges and four wet sponges were used to represent a healthy lung and a pneumonia consolidated lung respectively. The sound signals detected by the electronic stethoscope were analyzed using the Digital Signal Processing toolboxes in Audacity and MATLAB software. The difference in the resonant frequencies when the sound waves traveled through the dry and wet sponges was used to diagnose pneumonia. The device uses a non-invasive method which does not cause any health defects, unlike the chest x-ray method which can cause cancer due to its use of electromagnetic radiation to diagnose pneumonia. The results were then discussed for the design and application in pneumonia diagnosis in infants