Methods and apparatus to generate threshold values for state detection

1. An apparatus, comprising:

a threshold generator to maintain, in memory, a collection of audio data elements representative of sound levels present in an environment at respective times when ON-indications are detected for a monitored media device, the threshold generator to replace, in response to detection of a next ON-indication in the environment, one of the audio data elements in the memory with a new audio data element representing a sound level in the environment at a time of the next ON-indication; and

a selector to select, for a value of a threshold condition of a state detection analysis, one of the audio data elements in the memory corresponding to a lowest sound level, at least one of the threshold generator or the selector implemented by at least one of a processor or hardware.

2. The apparatus as defined in claim 1 , further including a counter to:

increment a count when an ON-indication is detected in the environment; and

trigger replacement of the oldest one of the audio data elements maintained in the memory in response to the count reaching a first number, wherein the memory is organized as a circular buffer.

3. The apparatus as defined in claim 1 , wherein the audio data elements represent respective audio gain levels, and the selector is to select the one of the audio data elements corresponding to the lowest sound level by selecting a highest one of audio gain levels.

4. The apparatus as defined in claim 1 , further including an adjustor to weight the value selected for the threshold condition according to a fixed weighting ratio.

5. The apparatus as defined in claim 1 , further including an audio data obtainer to populate the collection of the audio data elements with audio information when the ON-indications are detected.

6. The apparatus as defined in claim 1 , wherein the detection of the ON-indication includes detection of media identifying information in the environment.

7. The apparatus as defined in claim 1 , wherein the audio data elements include audio gain levels associated with automatic gain control functionality.

8. A method, comprising:

maintaining, by executing instructions with a processor, a collection of audio data elements in memory, the audio data elements representative of sound levels present in an environment at respective times when ON-indications are detected for a monitored media device;

in response to detection of a next ON-indication in the environment, replacing, by executing an instruction with the processor, one of the audio data elements in the memory with a new audio data element representing a sound level in the environment at a time of the next ON-indication; and

selecting, by executing an instruction with the processor, one of the audio data elements corresponding to a lowest sound level to be a value of a threshold condition of a state detection analysis.

9. The method as defined in claim 8 , wherein the replacing of the one of audio data elements includes discarding an oldest one of the audio data elements and adding the new audio data element corresponding to the time of the detection of the ON-indication.

10. The method as defined in claim 8 , further including, in response to the ON-indication being detected:

incrementing a count;

determining whether the count has reached a trigger value; and

when the count has reached the trigger value, triggering the identifying of the one of the audio elements corresponding to the lowest sound level.

11. The method as defined in claim 8 , further including adjusting the selected one of the audio elements according to a weighting ratio or an offset.

12. The method as defined in claim 8 , wherein the audio data elements include audio gain levels, and the selecting of the one of the audio data elements corresponding to the lowest sound level includes identifying a highest one of the audio gain levels.

13. The method as defined in claim 12 , wherein the audio gain levels are obtained from an automatic gain control component utilized by a media detector.

14. The method as defined in claim 8 , further including providing the selected one of the audio data elements to a comparator used to detect the ON-indication.

15. A tangible computer readable storage medium comprising instructions that, when executed, cause a machine to at least:

maintain, in memory, a collection of audio data elements representative of sound levels present in an environment at respective times when ON-indications are detected for a monitored media device;

replace, in response to detection of a next ON-indication in the environment, one of the audio data elements in the memory with a new audio data element representing a sound level in the environment at a time of the next ON-indication; and

select, for a value of a threshold condition of a state detection analysis, one of the audio data elements corresponding to a lowest sound level.

16. The storage medium as defined in claim 15 , wherein the instructions, when executed, cause the machine to update the collection of audio data elements by discarding an oldest one of the audio data elements and adding the new audio data element corresponding to the time of the detection of the ON-indication.

17. The storage medium as defined in claim 15 , wherein the instructions, when executed, cause the machine to, in response to the ON-indication being detected:

incrementing a count;

determining whether the count has reached a trigger value; and

when the count has reached the trigger value, triggering the identifying of the one of the audio elements corresponding to the lowest sound level.

18. The storage medium as defined in claim 15 , wherein the instructions, when executed, cause the machine to adjust the selected one of the audio elements according to a weighting ratio or an offset.

19. The storage medium as defined in claim 15 , wherein the audio data elements include audio gain levels, and the instructions, when executed, cause the machine to identify the one of the audio data elements corresponding to the lowest sound level by identifying a highest one of the audio gain levels.

20. The storage medium as defined in claim 15 , wherein the instructions, when executed cause the machine to provide the selected one of the audio data element to a comparator used to detect the ON-indication.