The Lightspeed is designed to cut low frequency noise. Are there any noise-reduction headsets designed to cut out the frequency range of human voices?

I asked a couple of manufacturers at the AOPA convention a few years ago, and at that time there were none. But there might be now, and not every manufacturer was at the convention.

A review of the Bose Quiet Comfort 15 and the Heil Quiet Phone Pro in the May 2010 QST said that those headsets are also designed to cut out low frequencies, and not the entire sound spectrum.

The SAS data step language was originally modeled after PL/I. Some recent additions (for example, the "object-oriented" interface) appear to have been modeled after C or other more recently fashionable languages.

If you are speaking of the data step language, it's not correct to say that "[m]ost of the functions automatically apply to a whole recordset at once"; that's a misunderstanding of the default data step iteration over records. Statements in the data step apply to one record at a time, going sequentially or in index order through the input - unless you've done something to make that not happen (which you can do - SAS is very flexible).

In many ways, SAS follows the same principle of least surprise as Perl and some other languages.

"Which cell phone company is best" really depends on your location, and on your definition of "best". In some places, Sprint will be best, in others it will be Verizon or T-Mobile, and it's even possible that AT&T is best somewhere. I personally have been happy with Sprint for both voice and data. If you live in an area where they have implemented high speed data, they might be the best choice. I have not experienced the constant data drops or poor customer service I saw at Verizon (people seem surprised when I say Sprint customer service has been good, but it has). T-Mobile supposedly rolled out high speed data across the country this month, but I haven't heard any reports of how well it works.