You could extract info based on the GetContainerAttribute( table::field ; "Duration" ) function, and display that underneath the container. There are a number of audio related metadata tags that can be calculated.
Thanks for your answer Mike, but it's not the solution for me: I need a dynamic time-display, showing the actual time of the current (playing) audio. GetContainerAttribute( table::field ; "Duration" ) only gives the total length of the audio-file.
The Filemaker audio-control shows the actual time-position, but is not resizable...