iOS7 Safari Html5 Audio Tag bugs

I just find bugs on iPhone5 upgraded with iOS7
Combination of [audio.play + new Audio] is unstable.

//This is sample source.

var audio1=new Audio(“[url of sound’s file]”);
…
…
…
// button’s touchstart event function
/********************
    case1 – play sounds well
********************/
function playButton(){
    audio1.play();
}

/********************
    case2 – can’t play sounds
********************/
function playButton(){
    audio1.play();
    var audio2 = new Audio(“[url of sound’s file]”);
}

/********************
    case1 – can’t play sounds well on 4G,3G mode
********************/
function playButton(){
    audio1.play();
    setTimeout(function(){
        var audio2 = new Audio(“[url of sound’s file]”);
    },500);
}