I have heard hin speak about you often heard有一种用法,这里不能用speaking么 Walking

I have heard hin speak about you often heard有一种用法,这里不能用speaking么 Walking
I haveheard hinspeak about you often
这里为什么不能用speaking
Walking along the river,we heardsomeone shoutingfor help.
这里为什么又能用ing了