Sparklines are one of Excel's built-in tools for visualising data. Strutt|Tools|Row Ops.|Add Sparkline(s) and Strutt|Tools|Row Ops.|Remove Sparkline(s) inserts (or removes) sparklines into Column F of the current row of the workbook, providing a spectrum shape 'graph' overlay to allow easy visualisation of the spectrum shape.
Note that the sparkline does not stop the user from using the cell for a rating (e.g. A-weighting of the spectrum), the sparkline is overlaid over the cell value.