point on the scan line are thus added as they are received in the delay chain one or several signals from transducer elements received at times differing less than the differential delay between input taps are connected to one and the same input tap on the delay chain simultaneously this of course assumes knowledge of the propagation speed of ultrasound in the tissue of the body under examination for soft tissue that can be examined with ultrasound the speed is usually assumed to be uniform and constant with this assumption it is possible for any point in the tissue and in particular any point on the scan line to predict the exact time of arrival of the echoes at each of the transducer elements according to the invention the current updating of the switching network or matrix 30 is done as described above the delay chain 31 has a maximum delay of some microseconds say 25 microseconds and in the order of one hundred input taps this means that in average the difference in delay between two neighboring input taps will be a few tens of nanoseconds say 25 nanoseconds when feeding a signal from a transducer element through the switching matrix 30 to an input tap 32 of.