An apparatus for detecting a fetal heartbeat includes circuitry to convert
acoustic energy representative principally of a maternal heartbeat into a
first electrical signal and circuitry to convert acoustic energy
representative of a maternal heartbeat and a fetal heartbeat into a
second electrical signal. The apparatus also includes circuitry to
process the first and second electrical to provide an electrical signal
principally representative of the fetal heartbeat and circuitry to
determine pitch periods of the signal principally representative of the
fetal heart beat.