前端 js 播放 base64 编码的 mp3，放出来杂音很大，请教是哪里出错了？

后端传来是 base64-encoded 的 mp3 音频的字符串，码率、声道这些信息（ sampleRate 、numChannels 、bitsPerSample 、dataLength ）不知道，直接放在<audio>中播放是正常的：

<audio controls>
  <source src="data:audio/mpeg;base64, base64-encoded-string"  type="audio/mpeg">
</audio>  

重新解码作为 blob 播放，放出来就很多杂音，这中情况是哪里的问题？

<script type="text/javascript">

    const audioContext = new (window.AudioContext || window.webkitAudioContext)();
    const decoder = new TextDecoder("utf-8");

    function base64ToArrayBuffer(base64) {
        const binary = atob(base64);
        const len = binary.length;
        const bytes = new Uint8Array(len);
        for (let i = 0; i < len; i++) {
            bytes[i] = binary.charCodeAt(i);
        }
        return bytes.buffer;
    }

    function playAudioChunk(base64) {
        const arrayBuffer = base64ToArrayBuffer(base64);
        audioContext.decodeAudioData(arrayBuffer).then((audioBuffer) => {
            const source = audioContext.createBufferSource();
            source.buffer = audioBuffer;
            source.connect(audioContext.destination);
            source.start(0);
        }).catch((err) => {
            console.error("Error decoding audio data", err);
        });
    }

    // ws-connection ...
    playAudioChunk(base64-encoded-string);  
    
</script>