receiver end event not triggering

const receiver = connection.receiver;

const audioStream = receiver.subscribe(user, {
    end: {
             behavior: 'after-silence',
             duration: 50
             }});

audioStream.on('data', (data) => {        
    const decoded = opusEncoder.decode(data);
    audioData = Buffer.concat([audioData, decoded]);
});

audioStream.on('end', () => {
    console.log("User stopped speaking");                    
});