    const submitBtn = document.getElementById('submit-btn');
        const btnText = document.getElementById('btn-text');
        const loadingSpinner = document.getElementById('loading-spinner');
        const errorText = document.getElementById('error-msg');
        const audioContainer = document.getElementById('audio-container');
        const audioPlayer = document.getElementById('audio-player');
        const advancedToggle = document.getElementById('advanced-toggle');
        const advancedIcon = doc