maths of flanging

[bluebunny]

Just found this posted on Muffs.  Quite interesting and not too long.

[StephenGiles]

Sorry, but for someone like myself who just managed to scrape a pass on O Level Maths, it's just gobbledegook!!!   

[Phend]

Hum, that Formula could make some nice art work on your next flanger build.

[Fancy Lime]

I flanged Maths class in tenth grade, too. And English, obviously...

[Mark Hammer]

Actually, it's the instructor that pooched English.  This has been a bone of contention with me for many years.  Far too often, the people assigned to teaching anything quantitative, be it physics, engineering, maths of various kinds, and most forms of computer science, are often the very LAST people who ought to be teaching it.  Comprehending something yourself does not equal being able to explain and/or convey it.  The broad perception is that BECAUSE someone understands some quantitative discipline well themselves, they should automatically be tasked with teaching it.  And because they are such piss-poor explainers, WE come to the tragic conclusion that it is US who are the incompetent ones.  The "For Dummies..." series of books only served to reinforce the public perception that if someone wrote appallingly obtuse and poorly-planned documentation for some computer application, that made no sense to you, the fault was your own intelligence, and not the fault of someone who couldn't explain their way out of a wet paper bag, but yet got paid and published to put their complete lack of skill on display.

I like to joke to first-time parents, or anyone pushing a shopping cart with a baby basket in it, that babies are the world's leading experts on ceilings (given that they spend all their time in the store staring up at them), but sadly they cannot tell us what they know.  The same is all-too-often true of those with quantitative expertise.

Two and half minutes into the guy's "instructional" video, and he has thrown a handful of furmulae at the viewer without ANY explanation, or even momentary reference to what they describe.  The assumption is that the viewer will understand all the implications and meanings at the same time as HE is thinking about them.  Wrong.  That's not how teaching works.  Almost as bad, if one looks at the comments in response to the Youtube video, in response to the title, he has clearly attracted viewers who are not going to understand more than 2% of what he says.  Great foresight, buddy.

NEXT!!

[bluebunny]

Sorry, but for someone like myself who just managed to scrape a pass on O Level Maths, it's just gobbledegook!!!   

I passed out during that formula bit in the middle, but the colours were pretty.   

[Fancy Lime]

Wow! He managed to make Mark "Canadian Buddha" Hammer mad. In many years on this forum, this is the first time I've seen that. I'm 100% with you, though: Bad teachers are the bane of civilization, probably since our ancestors first climbed down from the trees.

I haven't seen the vide yet and wasn't planning to since it was not critical for my silly pun. But now I'm intrigued. Flanging isn't all that complicated, I wonder how much someone can screw up the explanation.

Andy


Edit: Just now watched it. What a great example of How Not to Teach. The deriving of the formula is easy enough to follow but there is no connection to what it actually *means* in the real world. If I hadn't known before, I wouldn't've understood anything. Just say "Adding a delayed copy of a signal to the original creates constructive and destructive interference at various frequencies related to the delay time. We can calculate all points of total destructive interference in the spectrum from the delay time like so:..." It's really easy to show with a few plots, better yet animations. Show two sine waves atop of each other, one delayed by some amount, and the sum of both, then sweep the frequency. Easy visual explanation of the math. But if your only means of graphical communication is free-hand drawing with a mouse, for some reason, that's a bit of a pickle.


Edit 2: I have to add some points to Mark's remarks. What I learned when I started teaching is that trying to teach really exposes how well the teacher really understands the subject. A lot of people can answer questions on a test right without actually grasping the whole depth of the topic but to teach something well requires a lot more complete understanding. The old adage "those who can't do, teach" does not work in science and engineering. There is is "those who can't teach probably can't do too well either". There are exceptions, though. I know a few people who can do but not teach but nobody who can teach well but not do.

[iainpunk]

interesting video. i like how he keeps it short, was clear and isn't hard to follow.

thanks

edit: i see and understand the frustrations outed, but i dont sympathise with it in this case, as i have had all the appropriate maths classes to follow this and have a feeling i learned a lot, a different way of looking at what happens.

[Mark Hammer]

I'm 100% with you, though: Bad teachers are the bane of civilization, probably since our ancestors first climbed down from the trees.

I haven't seen the video yet and wasn't planning to since it was not critical for my silly pun. But now I'm intrigued. Flanging isn't all that complicated, I wonder how much someone can screw up the explanation.

And note that an electronic engineering department at a good school saw fit to give the guy a course to teach.  I'm sure he's a nice person - after all, he's teaching material of interest to us, AND his faculty web page notes that he plays keyboards and guitar - but like a great many (though not all) persons teaching quantitative curriculum, he's just not very skilled at it; at least not going by this particular video.  The shame is that people who might otherwise become very engaged in the material are stymied by how it is presented.

[Eb7+9]

The shame is that people who might otherwise become very engaged in the material are stymied by how it is presented.

@#$% me thats funnny

cogently converting s-domain math into Barbie doll talk is probably more of a challenge than Laplace faced when he was playing with these ideas back in 1785 ...

good video from a ballsy young person

[Rob Strand]

It makes perfect sense if you are into DSP maths.

The basic difference is a phaser uses phase shift and chorus/flangers use time-delay (which can be thought of as frequency dependent phase shift).   That should be obvious to virtually everyone on the group.

The math does just that.  Unfortunately not everyone has the background to bridge the gap between the two.