[Read the story.]
Mea culpa. Ever since my review of Andy Hertzfeld's collection of stories about the creation of the first Macintosh was published Monday night, a stream of e-mail has flowed into my in box explaining my failure to understand what it means to pass Steve Jobs' rhetoric through a "low-pass filter."
The distinction between what I wrote and what appears to be true is a little subtle, so rather than run a formal correction, or publish seven nearly identical letters, I'll just embarrass myself as publicly as possible with a complete rehash here.
I wrote that a low-pass filter cuts out high frequencies, so "when listening to Jobs, ignore all the times when he says something is 'great' or 'awful' -- the highs -- and just try to focus on the gist -- the low."
But I misunderstood what low and high frequencies really represent. A given "frequency" refers to the number of cycles over time. High frequencies change rapidly; low frequencies change more slowly.
One reader put it better than I can paraphrase:
"If Steve Jobs' opinion changes daily, then his opinion is a high-frequency signal. If Steve Jobs holds the same opinion for several days, even if he says something is 'great' or 'awful' (that's amplitude, not frequency), then it is a low-frequency signal, and Bud and Andy should probably pay attention to it."
And there you have it. Thanks to all the readers who took the time to point out the mistake.