I know I'm a little late and that there's already an answer but here is some code using the libraries discord.js and @discordjs/voice

npm i discord.js
npm i @discordjs/voice

//requirements
const discord = require('discord.js')
const voice = require('@discordjs/voice')
const client = new discord.Client({intents: Object.values(discord.Intents.FLAGS)}) //Object.values(discord.Intents.FLAGS) is used to get every intents 
//on ready
client.on('ready', () => {
    //log username
    console.log(client.user.username)
})
//
var connection
//when a message is sent
client.on('messageCreate', (message) => {
    //split message by args
    const args = message.content.split(' ')
    if(args[0] == "join") {
        //check if the message author is in a voice channel
        if(message.guild.members.cache.get(message.author.id) == null) return 
        //create a new voice connection (join a voice channel)
        connection = voice.joinVoiceChannel({
            channelId: message.guild.members.cache.get(message.author.id).voice.channel.id, //the id of the channel to join (we're using the author voice channel)
            guildId: message.guild.id, //guild id (using the guild where the message has been sent)
            adapterCreator: message.guild.voiceAdapterCreator //voice adapter creator
        })
        connection.receiver.speaking.on('start', (userId) => {
            //actions here
            console.log(userId)
        })
    }
    if(args[0] == "destroy") {
        if(connection == undefined) return message.channel.send('the bot isn\'t in a voice channel')
        //leave
        connection.destroy()
        connection = undefined
    }
})
client.login("token here")