Abstract: Methods and apparatus to control a state of data collection devices are disclosed. An example method includes generating a level of engagement based on an analysis of an audience associated with a media exposure environment; and controlling a state of a data collection device based on the level of engagement.

Abstract: Encoding and decoding methods and apparatus as described. An example method of obtaining auxiliary information in an audio signal using a plurality of frequency components residing in a plurality of code bands comprises transforming an audio signal into a frequency domain representation; determining characteristic of frequencies of the frequency domain representation that may contain the auxiliary information; normalizing across the code bands the characteristics of frequencies of the frequency domain representation in a respective one of the code bands that may contain the auxiliary information, wherein the normalization is carried out against a characteristic of a frequency in that code band; summing the normalized characteristics of the frequencies representative of auxiliary information to determine a sum for a frequency representative of auxiliary information; and determining that the sum is representative of the auxiliary information.

Abstract: Encoding and decoding methods and apparatus as described.

Abstract: Methods and apparatus to extract data encoded in media content are disclosed. An example method includes sampling a media content signal to generate digital samples, determining a frequency domain representation of the digital samples, determining a first rank of a first frequency in the frequency domain representation, determining a second rank of a second frequency in the frequency domain representation, combining the first rank and the second rank with a set of ranks to create a combined set of ranks, comparing the combined set of ranks to a set of reference sequences, determining a data represented by the combined set of ranks based on the comparison, and storing the data in a memory device.

Abstract: Methods and apparatus to extract data encoded in media content are disclosed. An example method includes receiving a media content signal, sampling the media content signal to generate digital samples, determining a frequency domain representation of the digital samples, determining a first rank of a first frequency in the frequency domain representation, determining a second rank of a second frequency in the frequency domain representation, combining the first rank and the second rank with a set of ranks to create a combined set of ranks, comparing the combined set of ranks to a set of reference sequences, determining a data represented by the combined set of ranks based on the comparison, and storing the data in a tangible memory.

Abstract: Example methods, apparatus and articles of manufacture to provide media content are disclosed. A disclosed example method includes receiving audio output by a first media presentation device, obtaining at least one of a Nielsen code or an Arbitron® code from the audio, the obtained code being representative of at least one of the first media content or a broadcaster of the first media content, obtaining second media content based on the extracted code, and presenting the second media content on a second media presentation device different from the first media presentation device.

Abstract: Methods and apparatus to audio watermarking and watermark detection and extracted are described herein. According to an example method, an identifier is encoded in media content when a different identifier has been previously encoded. According to another example method, messages decoded from media content are validated to provide improved decoding accuracy. In another example method, decoded symbols are stored in memory and synchronization symbols are located to detect a message encoded in media content.

Abstract: Methods and apparatus to encode and decode audio for shopper location and advertisement presentation tracking are disclosed. A method for tracking a shopper includes receiving a first audio signal at a first location with a decoder attached to a shopping implement, determining a first code encoded in the first audio signal, receiving a second audio signal at a second location with the decoder, determining a second code encoded in the first audio signal, and transmitting the first code and the second code to a data retrieval device.

Abstract: Encoding and decoding methods and apparatus as described.

Abstract: Signaturing methods and apparatus as described. In one example, a signaturing method includes capturing an audio signal, applying a first window function to a portion of the captured audio signal to produce a first windowed audio block, applying a second window function to the portion of the captured audio signal to produce a second windowed audio block, determining a first characteristic of a band of frequencies in the first windowed audio block, determining a second characteristic of the band of frequencies in the second windowed audio block, comparing the first characteristic to the second characteristic, and assigning a signature bit representative of the portion of the captured audio signal based on the comparison of the first characteristic and the second characteristic. Other examples are described.