Spectrum confidence interval

Dear useRs,

I'd like to plot a confidence interval on a periodogram. My problem is 
that spec.pgram(sunspots,ci=0.95,log="yes") gives me a blue error bar on 
the plot, but spec.pgram(sunspots,ci=0.95,log="no") does not. My 
questions are:
1. how should I plot the confidence interval with log="no"?
2. how should I get the min and max values of the confidence interval?
Many thanks for your help!
Clement Poirier