An evaluation method for an iterative watermark embedding process comprising: evaluating a watermarked electronic audio signal with both a quantitative quality evaluation and a robustness evaluation, wherein the quantitative quality evaluation evaluates the perceptual audio quality of the watermarked electronic audio signal relative to the original audio and provides an objective quality measure and the robustness evaluation modifies the watermarked electronic audio signal with distortion and provides a watermark robustness measure; determining, based on both the quality and robustness measures, whether to update embedding with updated parameters for a subsequent embedding iteration and if so, then determining the nature of the update for the subsequent embedding iteration, wherein: from the quantitative quality evaluation, if the quality measure falls below a desired quality level then the nature of the update comprises: increasing or decreasing watermark signal strength; or using an alternative watermark insertion method; and from the robustness evaluation, if the watermark robustness measure indicates that the watermark is likely to be unreliable, then the nature of the update comprises: increasing watermark signal strength; and/or updating the watermark insertion method. evaluating a watermarked electronic audio signal with both a quantitative quality evaluation and a robustness evaluation, wherein the quantitative quality evaluation evaluates the perceptual audio quality of the watermarked electronic audio signal relative to the original audio and provides an objective quality measure and the robustness evaluation modifies the watermarked electronic audio signal with distortion and provides a watermark robustness measure; determining, based on both the quality and robustness measures, whether to update embedding with updated parameters for a subsequent embedding iteration and if so, then determining the nature of the update for the subsequent embedding iteration, wherein: from the quantitative quality evaluation, if the quality measure falls below a desired quality level then the nature of the update comprises: increasing or decreasing watermark signal strength; or using an alternative watermark insertion method; and from the robustness evaluation, if the watermark robustness measure indicates that the watermark is likely to be unreliable, then the nature of the update comprises: increasing watermark signal strength; and/or updating the watermark insertion method. from the quantitative quality evaluation, if the quality measure falls below a desired quality level then the nature of the update comprises: increasing or decreasing watermark signal strength; or using an alternative watermark insertion method; and increasing or decreasing watermark signal strength; or using an alternative watermark insertion method; and from the robustness evaluation, if the watermark robustness measure indicates that the watermark is likely to be unreliable, then the nature of the update comprises: increasing watermark signal strength; and/or updating the watermark insertion method. increasing watermark signal strength; and/or updating the watermark insertion method.