Vinyl Presence

In the early days of recording the goal was to reproduce the music or whatever was being recorded as accurately as possible.  Early microphones, wax, and later shellac drums and disks, amplification horns and simple tube circuits were so inadequate, and very expensive, leaving little doubt whether you were listening to a recording or live music.  By the 1950s though, the technology began to catch up.  Speakers and amplifiers got better, microphones, got better, and perhaps most important, recording materials got better: better lathes, pressed vinyl disks, extremely lightweight diamond needles.  If everything was right, it was possible for a recording to win in a real A-B test.

One of the important things that was improved was that vague thing called "presence", which is based on our "ears" ability to place a sound accurately in a 3-D environment.   Our ancestors were both hunters and prey, and in such a context, this ability confers huge survival value.  So we have a whole bunch of very sophisticated mechanisms, most of which are almost completely instinctual.  Most of us cannot describe most of them, but they're there and they use them every day.  For  example, we use the slight difference in volume of a sound to place it left or right according to how our head is oriented.  We use difference in phase to determine whether this sound is close to on axis or how far away from the axis it is, giving us a 3 dimensional effect.  We use the pitch of the sound to determine how high it is: low sounds are lower, like rumbling or water, while breaking branches and flapping wings are higher.  And the most amazing part is that our brains and ears are doing this in milliseconds, on sounds that may not even have a full wave.

Early studio recordings were as acoustically as quiet as possible.   A room with as much sound insulation and damping as possible, so there would be no outside or reflective noise.  But as the techniques got better, it didn't take long to realize that something was missing.  The most important was reverberation: Every room, even a big outdoor performance arena, has a characteristic echo, and  recordings with no echo at all sounded weirdly sterile.  The solution was a device called a "spring reverb", which was a speaker and microphone connected to a short piece of spring, which would transmit sounds more slowly than air and could be adjusted fairly easily to produce a desired amount of echo.  Nowadays the same thing is done with digital electronics.

Next came stereo.  Two microphones were used in live situations and mixdowns to two tracks in studio situations to simulate the volume and phase difference that we use to detect position.  Attempts were made to do even better with 4 and more channels, but it turns out that they were getting into diminishing returns.  Some of these things still exist but they are mostly used for things like movie sound effects, so the rumbling or TIE fighter or whatever seems to be coming from behind you.

When the CD came along, one of the hobbies of audiophiles was to set up A-B tests between identical recordings on both CD and vinyl.  I participated in several.  With brand new vinyl and good equipment it was hard to tell.   Once the record had been played a dozen times or so, it was easy.  There were occasional scratches and pops, and there was a constant background hiss.

The way a stereo record is recorded, the lathe's cutter has two axes, each 45 degrees from the plane of the record and 90 degrees from each other.  A sound that's only to come from one speaker makes oscillations only on one, leaving the other stationary, and vice versa.  Since most sounds will come from both, this is mostly a 3 dimensional groove.

Imagine what happens when something happens to one of these tiny groves: a mote of dust lands on it, or a tiny scratch forms: the needle is deflected slightly from where it's supposed to be.  It's unlikely that this will be in perfect stereo phase so our animal brain puts it some random place in the sound field.  It's not even a full wave, so we don't actually register it.  Another comes along a few milliseconds later and we do the same thing at a different random place.  Our animal brain decides that whatever it is that's producing all of this has some size, and isn't just two disembodied speakers, but is present in the room.

CDs are unaffected by dust or scratches (at least within the limits) so they initially sounded sterile.  It isn't hard to synthesize "presence" though: just add a tiny amount 3D white noise.

addenda 27 Oct 2017

A lot of guitar amplifiers have a control called "presence", which slightly changes the equalization, boosting the upper midrange.  On some amps, this also includes some negative feedback for that range, which reduces distortion there, which are the fundamental pitch of the guitar are, but leaves (intentional) distortion alone across the rest of the spectrum--including white noise and the higher harmonics.

State Abbreviations

The US Postal Service processes a lot of mail, and a human used to read every letter.  To expedite this, they preferred specific abbreviations.  Prior to 1963, they used relatively spelled out ones, as I've spelled them in the Abbr. column.  In 1969, they decided upon a new set of two letter abbreviations.  The only one that's changed since is Nebraska, which had initialy been NB.  Canada asked them to change, due to a conflict with New Brunswick, so they switched to NE.

The interesting thing was that there had already been a two letter naming system in place, for the registration numbers of boats.  Mostly, they're the same, but in 10 states, highlited in RED, they are different. 

Postal	Name	Vessel	Abbr.
AL	Alabama	AL
AK	Alaska	AK
AR	Arkansas	AR
AZ	Arizona	AZ	Ariz
CA	California	CF	Calif
CO	Colorado	CO	Col
CT	Connecticut	CT	Conn
DE	Delaware	DL	Del
FL	Florida	FL	Fla
GA	Georgia	GA
HI	Hawaii	HA
ID	Idaho	ID
IL	Illinois	IL	Ill
IN	Indiana	In	Ind
IA	Iowa	IA
KS	Kansas	KA	Kan
KY	Kentucky	KY
LA	Louisiana	LA
ME	Maine	ME
MD	Maryland	MD
MA	Massachusetts	MS	Mass
MI	Michigan	MC	Mich
MN	Minnesota	MN	Minn
MS	Mississippi	MI	Miss
MO	Missouri	MO
NE	Nebraska	NB	Neb
NV	Nevada	NV	Nev
NH	New Hampshire	NH
NJ	New Jersey	NJ
NM	New Mexico	NM
NY	New York	NY
NC	North Carolina	NC
ND	North Dakota	ND
OH	Ohio	OH
OK	Oklahoma	OK
OR	Oregon	OR	Ore
PA	Pennsylvania	PA	Penn
RI	Rhode Island	RI
SC	South Carolina	SC
SD	South Dakota	SD
TN	Tennessee	TN	Tenn
TX	Texas	TX	Tex
UT	Utah	UT
VT	Vermont	VT
VA	Virginia	VA
WA	Washington	WN	Wash
WV	West Virginia	WV
WI	Wisconsin	WS
WY	Wyoming	WY

https://about.usps.com/who-we-are/postal-history/state-abbreviations.htm

59 Cruise Missiles

Thursday night, the new administration, in a major policy reversal, launched 59 Tomahawk cruise missiles to Shayrat airbase, which had launched a gas attack two days earlier.  But first he called the Russians to warn them, and apparently they warned the Syrian government in time to get most of their airplanes off the base.  Nevertheless, those 59 precision guided high explosives did so little damage to the airbase that the Syrians are using the airbase again two days later.  Apparently, they didn't do much damage.

What is this about?  Trump and quite a few others insist that seeing the children suffering from the gas attack changed his mind.  The deaths of 100,000 other children, many of them also by gas attacks, had apparently been insufficient.  Many people are saying that this is a change long overdue--that we should have attacked Syria in 2013 after a similar gas attack.  Obama asked congress for permission and was refused.

Syria is in the midst of a civil war.  A terrible drought led to economic tensions and Syrians had joined the "Arab Spring" demonstrations of 2010.  Assad had attacked peaceful demonstrators and they were off to the races.  Bush's idiotic invasion of Iraq 7 years earlier had created a particularly grim and media-savvy participant, which in Syria goes by a name which translates to Islamic State In Syria.  The republicans were right to put the brakes on Obama's warlike impulse and Trump had been right to stay out, no matter how horrible the events are.  There is no good that can come from participating in someone else's civil war.  The best we can hope is to put our thumb on the scale a little...provide intelligence and weapons to the side we want to win, for example.  There will be atrocities, and any participation makes us guilty by association.  65 years of meddling in the affairs of the middle east (starting with the 1953 coup in Iran) has resulted in a much less safe world and virtually no good for anybody.

I don't think it's about the Syrian children at all.  It is a distraction.  The probe of Russian interference in last years election is getting closer and closer to Trump himself, and a dozen or more close advisors are clearly guilty of some level of collusion.  These people conspired with a foreign power to install their puppet as president.  This is high treason.  Trump and his allies have been trying to deflect and obstruct the best they can, but for the moment, our institutions were still in place and the noose was tightening.

In another little bit of incompetence, Trump had signaled to Syria that he wouldn't respond to their atrocities.  He hadn't understood that he was doing that--he doesn't understand much--but once the Idlib attack happened, he did figure it out and realized he needed to correct the message.  This particular correction served several other purposes, too: it suggests that he might not be as beholden to his Russian puppeteers as we'd been thinking (except why did he warn them and not actually hit anything of consequence?).  It distracts from the outrage over the Gorsuch appointment.   It gives him brownie points from the hawks who wanted to participate in the civil war.  And most importantly of all, it deflects media attention away from the investigation of Russian meddling in the election.

It isn't quite a Reichstag fire, but if we fall for it, it may be enough.