bot.js

const Discord = require('discord.js');
const client = new Discord.Client();

client.on('ready', () => {
  console.log(`Logged in as ${client.user.tag}!`);
  let channel = client.channels.find('name', 'General');

    channel.join().then(connection => {

        const receiver = connection.createReceiver();

        connection.on('speaking', (user, speaking) => {
            console.log(user.username, 'speaking:', speaking);

            if (speaking) {

              const voiceStream = receiver.createOpusStream(user);
              voiceStream.on('data', chunk => {
                console.log(`voiceStream received: ${chunk}`);
              });
            }

        });
    });
});