Method for detecting which one of symbols of watermark data embedded in an original audio signal - by modifying sections of said original audio signal in relation to at least two different reference data sequences (REFP) - is present in a current section of a received version of the watermarked original audio signal (RWAS), wherein said received watermarked original audio signal can include noise and/or echoes, said method including the steps: - correlating in each case said current section of said received watermarked audio signal (RWAS) with candidates of said reference data sequences (REFP); - based on peak values in the correlation result values for said current audio signal section, detecting - using related values of false positive probability of detection of the kind of symbol - which one of the candidate symbols is present in said current audio signal section, characterised in that said false positive probability ( P) is calculated (21, L2, L3) in a recursive manner, wherein the total false positive probability for a given number of correlation result peak values is evaluated by using initially the false positive probabilities for a number smaller than said given of correlation result peak values, and by increasing gradually the number of considered correlation result peak values according to the required detection reliability, wherein for a first peak value and a first one of said candidate symbols said false positive probability is calculated, and: a) if the corresponding false positive probability is smaller than a predetermined threshold value, the current candidate symbol is assumed to be the correct symbol; b) if said false positive probability is not smaller than said predetermined threshold value, said false positive probability for said first peak value is calculated for the following one of said candidate symbols and the processing continues with step a); c) if none of the calculated false positive probability values is smaller than said predetermined threshold value, steps a) and possibly b) are continued for a following one of said peak values; d) if none of the calculated false positive probability values is smaller than said predetermined threshold value, the candidate symbol for which the minimum false positive probability has been calculated is assumed (23, 24) to be the correct symbol. - correlating in each case said current section of said received watermarked audio signal (RWAS) with candidates of said reference data sequences (REFP); - based on peak values in the correlation result values for said current audio signal section, detecting - using related values of false positive probability of detection of the kind of symbol - which one of the candidate symbols is present in said current audio signal section, characterised in that said false positive probability ( P) is calculated (21, L2, L3) in a recursive manner, wherein the total false positive probability for a given number of correlation result peak values is evaluated by using initially the false positive probabilities for a number smaller than said given of correlation result peak values, and by increasing gradually the number of considered correlation result peak values according to the required detection reliability, wherein for a first peak value and a first one of said candidate symbols said false positive probability is calculated, and: a) if the corresponding false positive probability is smaller than a predetermined threshold value, the current candidate symbol is assumed to be the correct symbol; b) if said false positive probability is not smaller than said predetermined threshold value, said false positive probability for said first peak value is calculated for the following one of said candidate symbols and the processing continues with step a); c) if none of the calculated false positive probability values is smaller than said predetermined threshold value, steps a) and possibly b) are continued for a following one of said peak values; d) if none of the calculated false positive probability values is smaller than said predetermined threshold value, the candidate symbol for which the minimum false positive probability has been calculated is assumed (23, 24) to be the correct symbol. a) if the corresponding false positive probability is smaller than a predetermined threshold value, the current candidate symbol is assumed to be the correct symbol; b) if said false positive probability is not smaller than said predetermined threshold value, said false positive probability for said first peak value is calculated for the following one of said candidate symbols and the processing continues with step a); c) if none of the calculated false positive probability values is smaller than said predetermined threshold value, steps a) and possibly b) are continued for a following one of said peak values; d) if none of the calculated false positive probability values is smaller than said predetermined threshold value, the candidate symbol for which the minimum false positive probability has been calculated is assumed (23, 24) to be the correct symbol.