This paper presents an alternative approach for heart rate measurement. Instead of using an ECG sensor, the proposed design uses sound signals received from a microphone which does not require skin-contact. Specifically, the design uses an air conductive microphone and an efficient algorithm to estimate the heart beat parameters of the wearer. The estimates are obtained for different activities undertaken by the wearer. The activities studied include sitting, jumping, reading, laughing, singing, and coughing. Data are collected from researchers and students working in the laboratory, and in the presence of lung sound, and other environmental sounds and noise. Preliminary results show that, the method can be an effective alternative means of monitoring cardiac (heart) sounds in a natural environment.