Inserting watermarks into audio signals that have speech-like properties

A machine or group of machines for watermarking audio, comprising:

• an input that receives an audio signal and watermark data payload information;
• an encoder configured to convert the watermark data payload information into a watermark audio signal including one or more watermark messages corresponding to the watermark data payload information, each of the one or more watermark messages comprising multiple symbols, each of the multiple symbols corresponding to a respective audio segment;
• and
• a processor configured to insert the one or more watermark messages into multiple spectral channels of the audio signal, wherein each of the multiple spectral channels occupies a different frequency range, and wherein bandwidth of a first spectral channel located in a first frequency region is smaller than bandwidth of a second spectral channel located in a second frequency region, and wherein the processor is configured to insert the one or more watermark messages such that bandwidth of a spectral channel, from the multiple spectral channels, is equal to a number divided by the time duration of a respective symbol, from the multiple symbols, in the spectral channel, wherein the number is in the range of 0.7 to 2.5.