Assuming you mean to have your post tagged as discord.js, see this post on a way to receive voice information.

Otherwise I'll answer assuming your tag was right and that you did mean discord.py, it does not support receiving voice data, only sending it. There has never been a "guildMemberSpeaking" attribute in the library.

Try this extension to discord.py: https://github.com/imayhaveborkedit/discord-ext-voice-recv

See this project that uses it for a reference: their voice.py file as well as voice_cb() in main.py