Dealing with Noise and Artifacts in Data Viewer

Often you can visually identify periods of noise or artifacts in 1D Data Viewer:

scratching artifact2

In NeuroExplorer version 5.014 or later, you can identify time intervals corresponding to artifacts using mouse:

– Right-click in 1D View to invoke context menu:

1dmenu1

– Specify ‘Select Interval Variable…’ menu command. NeuroExplorer will display the following dialog:

Specify Interval Variable to Add Intervals to

– Click ‘Create New Interval Variable…’ button:

New Variable Name

– Let’s create a new interval variable with the name noise. Type ‘noise’ (without quotes) and click OK to close this dialog, then click OK to close Select Interval Variable dialog.

– Note that the cursor now has ‘plus interval’ graphic:

intadd

– Press the left mouse button at the start of the noise interval, then drag the mouse until the end of the noise interval and release left mouse button. The new interval is added to noise interval variable:

added interval

– Add a second interval:

2intervals

– Hit ESC key to exit Add Interval mode

– We want to analyze data that is NOT in the noise intervals. To make this possible, right-click in 1D view again and select ‘Invert Interval Variable’ menu command:

invertintvar

– In the Invert Interval Variable dialog, select noise variable to be inverted:

Invert Interval Variable

– Now noise_inverted interval variable contains time intervals corresponding to our data without noise:

noiseinverted

– We can use noise_inverted variable in a Data Selection page of analysis properties dialog:

Analysis Properties data sel

and the data in noise intervals will be ignored.

There is also a faster way to get rid of noisy data — you can delete all the data in specified time intervals. To do this, right-click in 1D view and select ‘On Mouse Click and Drag, Delete…’ menu command:

deletemenu

– Now when you click and drag with the left mouse button, all the data in selected time interval are deleted:

deleted2

deleted3

Note that delete operation cannot be undone right away. You will need to reload the data file to restore original data.