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Comparative Histogram
(Forensics Version Only)
A companion tool to the “Histogram vs. Time” feature is the “Comparative Histogram”. It provides you with the ability to compare two different file sectors in terms of their probability distributions of the amplitude density of audio signal samples found on each file segment. This feature can be useful in Forensics audio authentication situations since audio recordings in a given recording environment often display a unique statistical character. The comparative histogram can be used to determine differences in this regard.
The vertical axis represents the frequency of the events scaled to 100% while the horizontal axis represents the amplitude counts within the selected area of the file. This feature can be useful in Forensics Audio authentication situations. It is sensitive to file portions which may have had varying bit depths when originally recorded. The graphs of sampled portions of a file are graphically over-laid upon one another so that a quick comparison of histogram data is provided.
File Mastered in both 16 and 8 Bit depth and edited together
Comparative Histogram of composite 16 and 8 Bit File Edits
The file used to generate the above histograms is called “Mary Had a Histogram (8 bit edit on 16 bit file)demo.wav”. The file itself is a 16 bit file, sampled at 44.1 kHz. But, it has an edit at the second yellow highlighted area using an 8 bit file converted to 16 bit and inserted into that time sector. You can’t hear or see the edit in the time domain display, however it shows clearly using the comparative histogram function. Note that the first yellow portion of the file is shown as the yellow distribution on the histogram. The second yellow section of the file is shown on the comparative histogram in red. Their signal distributions differ substantially showing that there was an error made by the person who attempted the edit. To use the Comparative Histogram, set the bins number to around 4000 initially. Then, highlight one sector of a file and click on Capture 1 and a yellow graph will be created. Then, highlight another (suspicious) sector of a file and click on Capture 2 and a red graph will be created and laid on top of the first graph for comparison. Note that you can also choose between a line graph (default mode) and a bar graph (checkbox).
(Forensics Version Only)
A companion tool to the “Histogram vs. Time” feature is the “Comparative Histogram”. It provides you with the ability to compare two different file sectors in terms of their probability distributions of the amplitude density of audio signal samples found on each file segment. This feature can be useful in Forensics audio authentication situations since audio recordings in a given recording environment often display a unique statistical character. The comparative histogram can be used to determine differences in this regard.
The vertical axis represents the frequency of the events scaled to 100% while the horizontal axis represents the amplitude counts within the selected area of the file. This feature can be useful in Forensics Audio authentication situations. It is sensitive to file portions which may have had varying bit depths when originally recorded. The graphs of sampled portions of a file are graphically over-laid upon one another so that a quick comparison of histogram data is provided.
File Mastered in both 16 and 8 Bit depth and edited together
Comparative Histogram of composite 16 and 8 Bit File Edits
The file used to generate the above histograms is called “Mary Had a Histogram (8 bit edit on 16 bit file)demo.wav”. The file itself is a 16 bit file, sampled at 44.1 kHz. But, it has an edit at the second yellow highlighted area using an 8 bit file converted to 16 bit and inserted into that time sector. You can’t hear or see the edit in the time domain display, however it shows clearly using the comparative histogram function. Note that the first yellow portion of the file is shown as the yellow distribution on the histogram. The second yellow section of the file is shown on the comparative histogram in red. Their signal distributions differ substantially showing that there was an error made by the person who attempted the edit. To use the Comparative Histogram, set the bins number to around 4000 initially. Then, highlight one sector of a file and click on Capture 1 and a yellow graph will be created. Then, highlight another (suspicious) sector of a file and click on Capture 2 and a red graph will be created and laid on top of the first graph for comparison. Note that you can also choose between a line graph (default mode) and a bar graph (checkbox).