<p>A method of determining an acoustic velocity in a segment of a bone covered with a layer of soft tissue having an outer surface, comprising: determining a first travel time of a first ultrasonic wave along a first path from said outer surface back to said outer surface which path includes at least a first part of said bone segment; determining a second travel time of a second ultrasonic wave along a second path from said outer surface back to said outer surface which path includes at least a second part of said bone segment; determining a third travel time of a third ultrasonic wave along a third path from said outer surface back to said outer surface which path includes at least a third part of said bone segment; and deriving said acoustic velocity in said segment of bone from said three determined travel times.</p>
