Metric on Mars

In article ,
(Markus Kuhn) wrote:

"Keith F. Lynch" writes:
I've played around with signal generators, speakers, and ultrasonic
transducers, and have come to the conclusion that plenty of people,
including me, can hear 20 kHz just fine.

If it's believed otherwise,
it's probably because most *speakers* can't reproduce that frequency.

Speakers, even singers, produce hardly any power spectral
density above 7-10 kHz.

I think he meant loudspeakers, not people.

Higher frequencies in music recordings are
mostly relevant for some percusive instruments.

If you don't think 10+kHz is relevant for music, then I think you're a
poor candidate to judge high-frequency hearing. To me, the difference
between digitized classical music with a 13kHz cutoff and an 18kHz cutoff
is striking, and I doubt anyone would consider horns and strings to be
percussive instruments.

Phil McKerracher wrote:

"John David Galt" wrote in message
.. .
Don Aitken wrote:
If you have 230 volt mains, yes. In countries where they are stuck
with 110 volts, the kettle method takes much longer, which is why most
American households don't even have one. Indeed, the very term
"electric kettle" is unfamiliar.

Actually, most American households are wired with 220V mains, but only
one or two large appliances (stove and clothes dryer) actually run at
that voltage. The rest of the house runs on 110V. (The two wires of
the 220V main are on opposite phases with respect to ground, so it's
110V from either one of them to ground.)

I don't see why Europe hasn't adopted our standard. Accidental shocks
at 110 are usually not fatal, while at 230 they are. While they're at
it they should adopt our 60 Hz rather than 50, which makes lights
flicker noticeably.

We're way off topic, but both systems are a compromise and I don't actually
think the European one is too bad. You need to keep below about 50V to be
"safe", which is why phone lines (and soon, cars) use that sort of voltage.
Even that can be fatal on wet skin. Power tools used outdoors in Europe
often do in fact use a 110V isolating transformer. Using a higher voltage
for other heavy loads saves a lot of money on cable and reduced losses, of
course.

You're right that voltage is only one of several important factors; I've
taken a jolt directly from a 12V car battery (dropped a wrench across the
terminals while changing out my water pump) that was enough to knock me
on my ass.

The real determining factor seems to be current * time, which is why the
GFCI (ELCB in Britain) is such a lifesaving device.

I promised my Mum a report on the coffee in Canada (where I have recently
been, in order to attend the IHW and PET workshops, which are respectively
the Information Hiding and Privacy Enancing Technologies workshops, and a
good thing they are), so you get lumbered with it too.

Says I, while drinking a cup of finest fresh Jamaican Blue Mountain, in
which the coffee has touched the water for a full but mere 28 seconds, in a
fast-filter situation, and which still has that spring-water quality because
it wasn't boiled for too long, never mind the extra "springy" quality such a
coffee can provide.

Wasteful? Who shall be my judge? Though I'll agree to test up to 35 seconds
in comparison.



Ah, home again, there's no place like it. Tomorrow morning I shall allow
myself some espresso "elephants', but that is another story.


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Coffee in Canada: a report:

Mostly, it is ****.

I got some OK stuff at specialist cafe's (not Starbucks, who were worse than
usual), and in the CN tower, but that was all. Nothing good. Even the
supermarket "better than regular blends" were crap, despite supposedly
having something European in their lineage.

I have a theory about that, which is another reason you get lumbered with
this report, so don't blame my mum. In all the hotel rooms they have coffee
makers - which use ground coffee, not instant, although the concept of
freshness gets no look in - which are underpowered, because they run on
110V.

This means that they slowly drip hot water over the coffee (with inaccurate
temperature control) over a period of several minutes. Ouch! Anyone who has
studied the theory of aliquots will realise that this is a very good way to
get everything even vaguely soluble from the ground coffee - but that is not
the right way to make good-tasting coffee.

Espresso" means "fast", and that is how coffee should be made. Making it
fast means that the nasty-tasting-and-slow-to-dissolve stuff, like the extra
caffeine you don't need, stays in the grounds, and not in the liquor. Making
it slow means that all the crud gets included too, the kind of stuff you
might get in reused coffee grounds. We don't want crud.



One innovation I have not seen before is the "one-cup filter", which is tiny
and no good - I use at least a "four-cup" size for a single cup of filter
coffee, in order to get fast seperation of the liquor and the grounds when
the brewing is done - these are the size of teabags. They supposedly fit on
a stick over a cup, and you fill them with ground coffee, and pour on the
hot water.

In simplistic theory they might be good, but in practice they don't work. I
did bring some filters back, but it is more likely that they will be of use
in freebasing cocaine than making decent coffee.


The existence of such drip machines in hotels is merely a symptom of the
general abuse put on coffee in Canada. They make fresh jugs of filtered
coffee, and mix the fresh jug with the remnants of the old. They leave jugs
for hours on hotplates. They make two jugs, in case they will need the
second.

As for espresso, they - well, I met only one real barista, who was young and
inexperienced, though she might turn out to be something eventually if her
bosses allow her to buy decent coffee. Which would probably have to be
specially imported. 'Nuff said.




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(taking the last sip of the Jamaican - damn, that is fine coffee!),


--
Peter Fairbrother