Abstract: A method for generating a signature is disclosed. As part of the method, a first number of bits are identified in respective rows of an audio signature matrix that are determined to be the strongest bits in the row, bits of the audio signature matrix are replaced with respective cells having values depending on whether the respective bits are included in the first number of bits, a set of uniformly distributed numbers are generated within a range of numbered locations corresponding to cells of the audio signature matrix; numerical distances are determined, from respective numbers in the set of uniformly distributed numbers, to the numbered locations of the matrix, associated with nearest occurrences of a first value. A set of integers is generated based on the distances.

Abstract: Methods and apparatus for determining increasing robustness of media signatures are disclosed. An example apparatus includes a characteristic analyzer to analyze a media signal based on a signature algorithm to identify a comparison between a first characteristic and a second characteristic that does not satisfy a threshold; and a characteristic enhancer to adjust at least one of the first characteristic or the second characteristic to satisfy the threshold.

Abstract: Methods, apparatus, systems and articles of manufacture are disclosed for media crediting and, more particularly, methods and apparatus of media device detection for minimally invasive media meters. An example apparatus disclosed herein to detect media devices presenting media comprises a cluster generator to generate a cluster of media locations from a reference population of media locations based on media identifying information received from a presentation of media at an unidentified media device at a first media location, a media device determiner to determine media devices available at the media locations in the cluster of media locations, a cluster based media device identifier to identify the unidentified media device based on the media devices available at the media locations in the cluster of media locations, and a media device report generator to generate a report on the identity of the unidentified media device.

Abstract: Methods and apparatus to analyze microphone placement for watermarks and signatures are disclosed. An example apparatus includes a signal transformer to determine a frequency spectrum of a received noise burst; a variance determiner to compute a variance of a frequency band in the frequency spectrum; and a detection rates determiner to determine a recovery rate of at least one of a watermark or a signature based on the computed variance.

Abstract: A method for generating a signature is disclosed. As part of the method, a first number of bits are identified in respective rows of an audio signature matrix that are determined to be the strongest bits in the row, bits of the audio signature matrix are replaced with respective cells having values depending on whether the respective bits are included in the first number of bits, a set of uniformly distributed numbers are generated within a range of numbered locations corresponding to cells of the audio signature matrix; numerical distances are determined, from respective numbers in the set of uniformly distributed numbers, to the numbered locations of the matrix, associated with nearest occurrences of a first value. A set of integers is generated based on the distances.

Abstract: Methods and apparatus for performing variable block length watermarking of media are disclosed. Disclosed example apparatus include means for selecting a first frequency from a set of frequencies based on a first symbol in a code, and for selecting a first block size based on the first symbol and the code, a combination of the first block size and the first frequency to represent the first symbol. Disclosed example apparatus also include means for synthesizing a code frequency according to the first block size and the first frequency. Disclosed example apparatus further include means for combining the code frequency with a first block of input audio samples of the audio having the first block size to form a block of encoded audio samples encoded with the first symbol, the code frequency and the first block of input audio samples to overlap in time.

Abstract: Methods, apparatus, systems and articles of manufacture to count people in an audience are disclosed. An example system includes means for transmitting a control signal to a portable device a threshold period of time after a person logs into a people meter separate from the portable device. The control signal causes the portable device to begin collecting location information and proximity information. The system also includes means for analyzing the location information to determine a location result indicative of a location of the portable device. The system further includes means for analyzing the proximity information to determine a proximity result indicative of whether the person is near the portable device. The location result and the proximity result collectively define first presence information. The first presence information indicative of whether the person is present in a media exposure environment associated with a media presentation device.

Abstract: Methods and apparatus to analyze microphone placement for watermarks and signatures are disclosed. An example apparatus includes a signal transformer to determine a frequency spectrum of a received noise burst; a variance determiner to compute a variance of a frequency band in the frequency spectrum; and a detection rates determiner to determine a recovery rate of at least one of a watermark or a signature based on the computed variance.

Abstract: Methods and apparatus for determining increasing robustness of media signatures are disclosed. An example apparatus includes a characteristic analyzer to analyze a media signal based on a signature algorithm to identify a comparison between a first characteristic and a second characteristic that does not satisfy a threshold; and a characteristic enhancer to adjust at least one of the first characteristic or the second characteristic to satisfy the threshold.

Abstract: Methods and apparatus for performing variable block length watermarking of media are disclosed. An example method to encode auxiliary data in audio data comprises selecting a frequency based on a code, selecting a block size based on the code, a combination of the block size and the frequency to represent of the code, encoding the code in an audio stream according to the block size and the frequency, and transmitting the audio stream including the encoded code.

Abstract: Methods, apparatus, systems and articles of manufacture to count people in an audience are disclosed. An example method includes analyzing location information collected by a portable device indicative of a location of the portable device. The method also includes analyzing proximity information collected by the portable device indicative of when a person is near the portable device. The example method further includes generating presence information based on (1) the location information and (2) the proximity information, the presence information being indicative of whether the person is present in a media exposure environment associated with a media presentation device.

Abstract: Methods and apparatus to identify an emotion evoked by media are disclosed. An example apparatus includes a synthesizer to generate a first synthesized sample based on a pre-verbal utterance associated with a first emotion. A feature extractor is to identify a first value of a first feature of the first synthesized sample. The feature extractor to identify a second value of the first feature of first media evoking an unknown emotion. A classification engine is to create a model based on the first feature. The model is to establish a relationship between the first value of the first feature and the first emotion. The classification engine is to identify the first media as evoking the first emotion when the model indicates that the second value corresponds to the first value.

Abstract: Methods and apparatus to audio watermarking and watermark detection and extracted are described herein. Disclosed example methods to decode a watermark from an audio signal include averaging a second sequence of audio samples stored in a buffer with a first sequence of audio samples stored in the buffer to determine an averaged sequence of audio samples, the second sequence of audio samples being related to the first sequence of audio samples based on a repetition period associated with watermark data of the watermark to be decoded. Disclosed example methods also include determining whether to enable a stacker. Disclosed example methods further include, in response to the stacker being enabled, decoding the watermark from the averaged sequence of audio samples, and in response to the stacker being disabled, decoding the watermark from the first sequence of audio samples.

Abstract: Methods and apparatus to identify a mood of media are disclosed. An example method includes accessing a known audio known to evoke a first emotion. A first synthesized sample is synthesized based on the known audio sample. A first value of a first feature of the first synthesized sample is calculated. A mood model is created based on the first feature. The mood model is to establish a relationship between the first feature and the first emotion. A second value of the first feature of first media evoking an unknown emotion is identified. The unknown emotion is identified as the first emotion when the mood model indicates that the second value corresponds to the first value.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to detect media watermarks in magnetic field data are disclosed herein. Example media monitoring methods disclosed herein include accessing magnetic field data determined by a magnetometer, the magnetic field data associated with a first sampling rate. Disclosed example methods also include transforming magnitude values of the magnetic field data to a frequency domain to determine transformed magnetic field data. Disclosed example methods further include evaluating a portion of the transformed magnetic field data associated with a first frequency to detect a media watermark having a frequency component associated with a second frequency different from the first frequency, the first frequency being aliased relative to the second frequency based on the first sampling rate.

Abstract: Methods and apparatus to tracker web browsing sessions are disclosed. An example method includes determining, by executing an instruction with a processor, if web pages accessed by browsers are associated with a known browsing session by matching numbers received in association with accesses to the web pages with a plurality of random numbers generated based on a known seed value, wherein the numbers are generated by random number generators of the browsers. The method further includes determining, by executing an instruction with the processor, a subset of the web pages corresponding to the known browsing session and to storing the association of the subset and the known browsing session in a browsing session database.

Abstract: Example methods, apparatus, systems and articles of manufacture to implement down-mixing compensation for audio watermarking are disclosed. Example watermark embedding methods disclosed herein include determining a first attenuation factor associated with a first audio channel of a multi-channel audio signal based on first down-mixed audio samples obtained from down-mixing the first audio channel and a second audio channel of the multi-channel audio signal, determining a second attenuation factor associated with a third audio channel of the multi-channel audio signal based on second down-mixed audio samples obtained from down-mixing the second audio channel and the third audio channel of the multi-channel audio signal, selecting one of the first attenuation factor or the second attenuation factor to be a third attenuation factor associated with the second audio channel of the multi-channel audio signal, and embedding a watermark in the second audio channel based on the third attenuation factor.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to detect media watermarks in magnetic field data are disclosed herein. Example methods disclosed herein to detect media watermarks can include accessing multidimensional magnetic field data representative of values of a magnetic field measured within a first distance of audio circuitry that is to output an audio signal corresponding to media presented by a media device. Such example methods can also include processing the multidimensional magnetic field data to detect a watermark included in the audio signal.

Abstract: Methods and apparatus to tracker web browsing sessions are disclosed. An example method includes computing a sequence of numbers to be generated by a random number generator during a first browsing session associated with a browser given a first seed value; and determining whether a web site visit is associated with the first browsing session based on a received number.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to embed information in generated acoustic signals are disclosed. Example methods disclosed herein to embed information in an acoustic signal output from an electric vehicle include obtaining a first audio signal to be used to generate the acoustic signal. Such example also include combining a second signal with the first audio signal, the second signal to convey first digital information that, when detected, indicates a presence of the electric vehicle. Such example methods further include providing the first audio signal with the second signal to an audio circuit that is to output the acoustic signal from the electric vehicle.