This chapter introduces time-spread echo hiding as an advanced audio watermarking method based on echo hiding. After reviewing some relevant researches, theoretical derivation of echo hiding and time-spread echo hiding is presented. As for embedding process, differences in the structure of echo kernels between the ordinary echo hiding and the time-spread echo hiding are schematically depicted to explain advantages of the new method. Several watermark-extracting methods are introduced for decoding process to raise the detection rate for various conditions. Performance of the method in robustness against several attacks is evaluated in terms of d’ because of its statistical preciseness. Results of computer simulations tell that the time-spread echo hiding show fairly better performance than the ordinary echo hiding.