Hi, Sorry for the delayed response.
I could actually solve the problem by uninstaling pulseaudio. It was installed on my system because I thought my speech synthesis does require it but I discovered yesteday that it is not the case. So I uninstalled it and now mpg123 works again. Many thanks for your support Thomas and for the development of mpg123 which is, according to me, a very cool program. Best wishes, Shérab.