Abstract: In some aspects, the present invention provides a method of measuring bone condition using ultrasound waves. Embodiments can involve transmitting an ultrasonic signal through a portion of a bone to be measured to a receiver. The first and second harmonics of the detected signal can then be isolated. A duration difference can then be determined between (i) the detected signal or a first harmonic of the detected signal and (ii) a higher harmonic of the detected signal. Based on that duration difference, material conditions of the bone can be estimated. Methods according to the present invention can be significantly more robust and repeatable than known methods of measuring bone conditions.