This option determines the spectrum bar's peak hold time, in milliseconds. It's only relevant when peaks are being shown, i.e. when Show Peaks isn't "Off". The bigger the hold time, the longer peaks are held. If the hold time is zero, peaks aren't held, and begin decaying immediately. If the hold time is large (e.g. 10,000), peaks rarely or never decay, until the plot is reset. To reset the plot, use the Reset command in the Spectrum bar's context menu, or switch to a different document.