.audioButton {
    background: url("../images/btn_play.png") no-repeat;
    width: 19px;
    height: 19px;
    text-indent: -999999px;
    float: left;
}

    .audioButton:hover {
        background: url("../images/btn_play.png") no-repeat;
    }

    .audioButton.playing {
        background: url("../images/btn_stop.png") no-repeat;
    }

        .audioButton.playing:hover {
            background: url("../images/btn_stop.png") no-repeat;
        }

    .audioButton.loading,
    .audioButton.loading:hover {
        background: url("../images/loading.gif") no-repeat;
        text-indent: 0 !important;
    }