WEBVTT 00:00:00.000 --> 00:00:03.350 I mean, you are likely sitting, uh... mere inches 00:00:03.350 --> 00:00:05.490 away from a device right now that is capable 00:00:05.490 --> 00:00:07.870 of translating the physical pressure of the air 00:00:07.870 --> 00:00:10.429 around you into a voltage. And then, you know, 00:00:10.509 --> 00:00:13.009 it beams that to space and back in milliseconds. 00:00:13.269 --> 00:00:15.070 Right. Which is just staggering when you really 00:00:15.070 --> 00:00:16.710 pause to think about it. It is. If you're at 00:00:16.710 --> 00:00:18.710 a desk or, you know, holding your phone, you're 00:00:18.710 --> 00:00:20.629 staring right at it. It probably just looks like 00:00:20.629 --> 00:00:23.530 a tiny pinhole or maybe a sleek metal cylinder. 00:00:23.850 --> 00:00:26.170 You click unmute on a video call. The little 00:00:26.170 --> 00:00:28.670 icon turns green and instantly your voice is 00:00:28.670 --> 00:00:31.629 transported across the globe. We just we expect 00:00:31.629 --> 00:00:34.719 it to work. Yeah, it feels entirely magical to 00:00:34.719 --> 00:00:37.979 us now. I mean, the translation of physical invisible 00:00:37.979 --> 00:00:40.320 air pressure into structured digital information 00:00:40.320 --> 00:00:42.859 is something modern society just treats as a 00:00:42.859 --> 00:00:44.960 basic given. But when you actually stop and look 00:00:44.960 --> 00:00:47.060 at how that invisible transfer happens, how we 00:00:47.060 --> 00:00:49.600 capture sound and turn it into electricity, it 00:00:49.600 --> 00:00:52.829 is anything but simple. It is a wild, messy story. 00:00:53.070 --> 00:00:55.810 So today we are taking a deep dive into a massive 00:00:55.810 --> 00:00:58.450 set of source materials, mostly centered around 00:00:58.450 --> 00:01:01.090 this incredibly comprehensive Wikipedia article 00:01:01.090 --> 00:01:04.489 simply titled Microphone. Which is quite the 00:01:04.489 --> 00:01:06.890 read. Oh, it really is. And omniscient for you 00:01:06.890 --> 00:01:09.849 today is to trace this incredible journey. We 00:01:09.849 --> 00:01:13.650 are going to explore how humanity went from using 00:01:14.409 --> 00:01:17.969 basic acoustic cones in ancient theaters to eventually 00:01:17.969 --> 00:01:21.530 capturing the literal heartbeat of a snail. Yeah, 00:01:21.689 --> 00:01:24.549 and along the way we will uncover the invisible 00:01:24.549 --> 00:01:27.209 three -dimensional geometry of sound that is 00:01:27.209 --> 00:01:29.670 happening all around you right now. because the 00:01:29.670 --> 00:01:32.730 technology inside that little unmute button relies 00:01:32.730 --> 00:01:36.090 on physics that really challenge our basic understanding 00:01:36.090 --> 00:01:38.609 of how the physical world operates. Okay, let's 00:01:38.609 --> 00:01:41.170 unpack this, because to really appreciate the 00:01:41.170 --> 00:01:43.450 sleek technology sitting on your desk, we have 00:01:43.450 --> 00:01:45.349 to go back to the beginning. And the beginning 00:01:45.349 --> 00:01:48.010 of capturing and projecting sound was frankly 00:01:48.010 --> 00:01:50.209 bizarre. It was highly contested, incredibly 00:01:50.209 --> 00:01:53.390 lucrative, and in some early cases, extremely 00:01:53.390 --> 00:01:55.510 dangerous. It really was. If we look way back 00:01:55.510 --> 00:01:57.510 in the historical record, the fundamental problem 00:01:57.510 --> 00:01:59.659 was always volume. Right. Like, how do you get 00:01:59.659 --> 00:02:02.019 a fragile human voice to reach a massive group 00:02:02.019 --> 00:02:04.140 of people? Without just screaming yourself hoarse. 00:02:04.400 --> 00:02:07.200 Exactly. So the earliest known attempts were 00:02:07.200 --> 00:02:10.800 just acoustic megaphones. We're talking 5th century 00:02:10.800 --> 00:02:14.580 BC Greece. Actors in these large outdoor amphitheaters 00:02:14.580 --> 00:02:17.819 wore these massive heavy theater masks, and they 00:02:17.819 --> 00:02:20.900 had specially designed horn -shaped mouth openings 00:02:20.900 --> 00:02:23.199 carved right into them. So the mask itself was 00:02:23.199 --> 00:02:25.960 basically a giant acoustic amplifier. Precisely. 00:02:26.030 --> 00:02:28.229 That makes sense, just physically funneling the 00:02:28.229 --> 00:02:30.889 air. And then, jumping ahead, you have Robert 00:02:30.889 --> 00:02:33.650 Hooke, the English physicist in the 17th century, 00:02:34.210 --> 00:02:36.569 creating essentially the first tin can telephone 00:02:36.569 --> 00:02:39.129 using stretch wire and cups. But that's still 00:02:39.129 --> 00:02:41.430 all just moving physical sound waves around through 00:02:41.430 --> 00:02:43.210 tension and funnels. Right. It's mechanical. 00:02:43.330 --> 00:02:45.569 The real leap, the moment everything completely 00:02:45.569 --> 00:02:48.330 changed, was when humanity decided to mix sound 00:02:48.330 --> 00:02:50.310 with electricity. Which is where the danger comes 00:02:50.310 --> 00:02:52.409 out. Oh, absolutely. That transition to electrical 00:02:52.409 --> 00:02:54.789 telecommunication is where things get genuinely 00:02:54.789 --> 00:02:58.159 chaotic. By 1876, you have Alexander Graham Bell 00:02:58.159 --> 00:03:00.319 and Elisha Gray, who developed what was called 00:03:00.319 --> 00:03:02.360 the liquid transmitter. OK, this is the part 00:03:02.360 --> 00:03:04.319 of the source material that absolutely blew my 00:03:04.319 --> 00:03:06.379 mind. When I was reading this, it sounded like 00:03:06.379 --> 00:03:08.639 a dangerous high school chemistry experiment 00:03:08.639 --> 00:03:12.560 gone horribly wrong because early telecommunication 00:03:12.560 --> 00:03:15.479 literally relied on talking into a cup of acid. 00:03:16.039 --> 00:03:19.439 It was a very literal, highly physical mechanism. 00:03:20.120 --> 00:03:22.819 The liquid transmitter consisted of a metal cup 00:03:22.819 --> 00:03:25.569 filled with water. And they mixed in a small 00:03:25.569 --> 00:03:28.750 amount of sulfuric acid to make that water electrically 00:03:28.750 --> 00:03:31.330 conductive. Because plain water isn't quite conductive 00:03:31.330 --> 00:03:33.550 enough for this, right? Right. And then a diaphragm, 00:03:33.689 --> 00:03:35.610 which is the membrane that vibrates when sound 00:03:35.610 --> 00:03:39.050 waves hit, was attached to a small needle. And 00:03:39.050 --> 00:03:42.189 that needle sat just barely submerged inside 00:03:42.189 --> 00:03:44.430 this acid solution. So let me get this straight. 00:03:44.610 --> 00:03:48.240 You speak. Your voice physically pushes the diaphragm, 00:03:48.340 --> 00:03:50.500 and the diaphragm pushes this needle up and down 00:03:50.500 --> 00:03:52.680 in the acid. Exactly. And as the needle moved 00:03:52.680 --> 00:03:55.699 up and down, the size of the water meniscus pinned. 00:03:55.860 --> 00:03:58.319 The meniscus, meaning the poo. The little curve 00:03:58.319 --> 00:04:01.379 of liquid clinging to the metal needle. Oh, right. 00:04:01.520 --> 00:04:04.699 OK. So that meniscus would change in size. And 00:04:04.699 --> 00:04:06.840 that physical movement altered the electrical 00:04:06.840 --> 00:04:09.539 resistance in the circuit. That fluctuating resistance 00:04:09.539 --> 00:04:12.240 created a fluctuating electrical current that 00:04:12.240 --> 00:04:14.300 perfectly matched the sound waves of the voice. 00:04:14.580 --> 00:04:17.819 That is wild. It is. The famous first phone conversation 00:04:17.819 --> 00:04:20.360 between Bell and Watson, the Mr. Watson come 00:04:20.360 --> 00:04:22.740 here moment that was conducted using a sloshing 00:04:22.740 --> 00:04:25.379 water microphone just like this. It's incredible 00:04:25.379 --> 00:04:28.319 to think about, but obviously carrying around 00:04:28.319 --> 00:04:30.699 a cup of highly corrosive sulfuric acid isn't 00:04:30.699 --> 00:04:33.139 exactly practical for consumer electronics or 00:04:33.139 --> 00:04:35.620 like putting a phone in everyone's living room. 00:04:35.959 --> 00:04:39.100 Which brings us to the late 1870s and one of 00:04:39.100 --> 00:04:41.439 the most bitter patent wars in technological 00:04:41.439 --> 00:04:44.100 history, the battle over the carbon microphone. 00:04:44.420 --> 00:04:46.800 The stakes were astronomical here. Right. You 00:04:46.800 --> 00:04:49.160 have David Edward Hughes, Thomas Edison and Emile 00:04:49.160 --> 00:04:51.319 Berliner all fighting viciously for the credit. 00:04:51.819 --> 00:04:53.920 We really have to remember the context of the 00:04:53.920 --> 00:04:57.319 1870s here. Long distance communication was the 00:04:57.319 --> 00:04:59.639 space race of that era. The financial stakes 00:04:59.639 --> 00:05:02.220 were almost unimaginable. Whoever controlled 00:05:02.220 --> 00:05:04.959 the patent for a clear, reliable telephone signal 00:05:04.959 --> 00:05:07.480 was going to control global commerce. So who 00:05:07.480 --> 00:05:10.040 actually got there first? Well, Hughes actually 00:05:10.040 --> 00:05:12.759 demonstrated a working carbon microphone first. 00:05:13.500 --> 00:05:16.120 But Edison possessed a formidable legal team 00:05:16.120 --> 00:05:18.759 and eventually secured the patent after a massive 00:05:18.759 --> 00:05:21.920 dispute. And then Berliner refined the design 00:05:21.920 --> 00:05:24.319 for Bell's telephone company just to keep them 00:05:24.319 --> 00:05:27.470 in the race. But why was the carbon microphone 00:05:27.470 --> 00:05:29.990 worth fighting over in the first place? Like, 00:05:30.069 --> 00:05:32.709 what made a capsule full of crushed carbon so 00:05:32.709 --> 00:05:35.350 special compared to the acid bath? It comes down 00:05:35.350 --> 00:05:38.370 to a monumental breakthrough in physics, specifically 00:05:38.370 --> 00:05:41.470 a concept called a Brown's Relay. Okay, lay that 00:05:41.470 --> 00:05:44.449 out for us. So a carbon microphone uses a small 00:05:44.449 --> 00:05:47.029 capsule filled with loose carbon granules pressed 00:05:47.029 --> 00:05:49.949 between two metal plates. When sound waves hit 00:05:49.949 --> 00:05:52.870 the diaphragm, it physically squeezes those carbon 00:05:52.870 --> 00:05:55.050 granules together. OK. When they're compressed, 00:05:55.509 --> 00:05:57.509 the surface area contact between the millions 00:05:57.509 --> 00:06:00.069 of little granules increases, which lowers the 00:06:00.069 --> 00:06:02.629 electrical resistance. And then when the diaphragm 00:06:02.629 --> 00:06:05.230 pulls back, the granules loosen up and the resistance 00:06:05.230 --> 00:06:06.949 goes up. Wait, I want to make sure I understand 00:06:06.949 --> 00:06:08.410 this, because it sounds like it's just changing 00:06:08.410 --> 00:06:10.470 resistance again, exactly like the liquid mic 00:06:10.470 --> 00:06:12.910 did with the needle. It is changing resistance, 00:06:13.129 --> 00:06:15.930 yes. But the carbon microphone doesn't just pass 00:06:15.930 --> 00:06:20.009 a weak signal along. It acts as an active amplifier. 00:06:21.199 --> 00:06:24.079 Think of a tiny sound wave as a person turning 00:06:24.079 --> 00:06:27.199 a valve on a massive city fire hydrant. Ooh, 00:06:27.199 --> 00:06:30.240 I like this. The person's fraggle voice isn't 00:06:30.240 --> 00:06:32.379 providing the immense water pressure the city's 00:06:32.379 --> 00:06:35.259 electrical grid is doing that. The voice is just 00:06:35.389 --> 00:06:38.490 the hand turning the valve, releasing a massive 00:06:38.490 --> 00:06:41.189 surge of electricity to push the signal miles 00:06:41.189 --> 00:06:43.889 down a wire. Oh, that is a brilliant way to visualize 00:06:43.889 --> 00:06:46.129 it. It's taking a whisper and using it to turn 00:06:46.129 --> 00:06:48.550 a massive electrical faucet on and off. Exactly. 00:06:48.670 --> 00:06:50.730 I mean, before the invention of vacuum tubes 00:06:50.730 --> 00:06:53.290 or digital amps, this was the only way to make 00:06:53.290 --> 00:06:55.790 long distance telephone calls possible. The sound 00:06:55.790 --> 00:06:58.269 of your voice was physically modulating a massive 00:06:58.269 --> 00:07:00.509 electrical signal. And that amplification is 00:07:00.509 --> 00:07:02.629 literally what connected the continents. But 00:07:02.629 --> 00:07:05.279 and this is a big but. while carbon mics were 00:07:05.279 --> 00:07:07.759 incredibly durable for early phones. I mean, 00:07:07.839 --> 00:07:10.079 you could drop them, slam them down in anger. 00:07:10.300 --> 00:07:13.259 The classic angry hang up. Right. But the audio 00:07:13.259 --> 00:07:16.139 quality was famously terrible. It sounded muffled, 00:07:16.500 --> 00:07:19.240 scratchy, and really harsh. So as the world moved 00:07:19.240 --> 00:07:22.360 into the 1920s, the era of radio broadcasting 00:07:22.360 --> 00:07:25.160 and commercial music recording demanded something 00:07:25.160 --> 00:07:28.300 entirely different. The industry needed high 00:07:28.300 --> 00:07:31.189 fidelity. And that demand leads us directly to 00:07:31.189 --> 00:07:33.509 the big three microphone technologies that still 00:07:33.509 --> 00:07:35.870 completely dominate the recording industry today. 00:07:36.310 --> 00:07:39.370 If you walk into a multimillion dollar recording 00:07:39.370 --> 00:07:41.310 studio right now, you are essentially looking 00:07:41.310 --> 00:07:44.689 at technology invented in the 1910s and 1920s. 00:07:44.790 --> 00:07:47.389 Yeah, the foundation of modern studio sound began 00:07:47.389 --> 00:07:50.050 with the condenser microphone. This was invented 00:07:50.050 --> 00:07:53.529 by EC Wente at Western Electric in 1916. And 00:07:53.529 --> 00:07:56.310 this was the first major leap toward truly lifelike 00:07:56.310 --> 00:07:58.610 fidelity. So this one throws out the carbon entirely 00:07:58.610 --> 00:08:00.790 and relies on static electricity, right? It operates 00:08:00.790 --> 00:08:03.569 on the principle of capacitance. Think of a capacitor 00:08:03.569 --> 00:08:05.930 as two metal plates sitting very close together, 00:08:06.370 --> 00:08:09.029 separated by a tiny gap of air holding an electrical 00:08:09.029 --> 00:08:12.149 charge. OK, two charged plates. Right. In a condenser 00:08:12.149 --> 00:08:15.410 microphone, one plate is fixed and solid. The 00:08:15.410 --> 00:08:17.569 other plate is the diaphragm itself, which is 00:08:17.569 --> 00:08:19.930 made of a material so incredibly thin and lightweight 00:08:19.930 --> 00:08:22.639 it's almost microscopic. When sound waves hit 00:08:22.639 --> 00:08:25.439 that diaphragm, it vibrates, which changes the 00:08:25.439 --> 00:08:27.540 physical distance between those two charged plates. 00:08:27.740 --> 00:08:29.819 And because they are holding a charge, changing 00:08:29.819 --> 00:08:32.419 that tiny distance changes the capacitance, which 00:08:32.419 --> 00:08:34.840 generates our audio signal. I like to picture 00:08:34.840 --> 00:08:37.059 it this way for you listening. A condenser mic 00:08:37.059 --> 00:08:39.419 is like a hypersensitive, ultra -lightweight 00:08:39.419 --> 00:08:42.259 trampoline. It has virtually no mass, so it picks 00:08:42.259 --> 00:08:45.399 up every single breath, every lip smack, every... 00:08:45.210 --> 00:08:48.009 tiny acoustic nuance in the room. And that lack 00:08:48.009 --> 00:08:50.929 of mass is the secret to its detail. It has zero 00:08:50.929 --> 00:08:53.230 inertia holding it back, so it reacts instantly 00:08:53.230 --> 00:08:55.690 to the smallest changes in air pressure. That's 00:08:55.690 --> 00:08:58.029 why legendary mics like the Newman U -47, which 00:08:58.029 --> 00:09:00.750 was introduced in 1949 with a vacuum tube amplifier, 00:09:01.269 --> 00:09:04.269 they set the gold standard for those warm, incredibly 00:09:04.269 --> 00:09:07.190 intimate vocal recordings we associate with classic 00:09:07.190 --> 00:09:09.870 studio albums. Like Sinatra. Sinatra. The Beatles, 00:09:09.870 --> 00:09:12.289 they relied completely on that sensitivity. But 00:09:12.289 --> 00:09:14.289 that sensitivity comes with a heavy trade -off. 00:09:14.519 --> 00:09:17.460 Condensers are super delicate, and because they 00:09:17.460 --> 00:09:19.500 need that electrical charge across the plates 00:09:19.500 --> 00:09:22.259 before you even make a sound, they require an 00:09:22.259 --> 00:09:24.559 external power source. Right, which the industry 00:09:24.559 --> 00:09:27.600 calls phantom power. Right. Usually, 48 volts 00:09:27.600 --> 00:09:30.039 sent right up the microphone cable. So if you're 00:09:30.039 --> 00:09:32.639 in a loud, chaotic, dangerous environment, like 00:09:32.639 --> 00:09:36.080 a live heavy metal concert, a delicate condenser 00:09:36.080 --> 00:09:38.379 isn't going to survive the night. Not at all. 00:09:38.740 --> 00:09:40.919 For durability, engineers turned to the second 00:09:40.919 --> 00:09:43.700 of the big three, the dynamic microphone, invented 00:09:43.700 --> 00:09:47.639 around 1923. It abandons charge plates entirely 00:09:47.639 --> 00:09:50.500 and operates on electromagnetic induction. This 00:09:50.500 --> 00:09:52.480 is where we get the rugged tanks of the audio 00:09:52.480 --> 00:09:54.960 world. The most famous example from the sources 00:09:54.960 --> 00:09:58.340 is the Shure SM57, which was released in 1965. 00:09:59.139 --> 00:10:01.940 You can put an SM57 half an inch away from a 00:10:01.940 --> 00:10:04.320 screaming guitar amp or a snare drum, you can 00:10:04.320 --> 00:10:06.299 drop it down a flight of stairs, and it won't 00:10:06.299 --> 00:10:08.399 distort or break. It's basically indestructible. 00:10:08.480 --> 00:10:10.000 But how does it handle that much punishment? 00:10:10.220 --> 00:10:13.539 Well, instead of fragile plates, a dynamic microphone, 00:10:13.679 --> 00:10:16.080 which is also known as a moving coil microphone, 00:10:16.559 --> 00:10:18.980 uses a diaphragm attached to a small coil of 00:10:18.980 --> 00:10:22.120 copper wire. and this coil sits suspended inside 00:10:22.120 --> 00:10:25.740 a permanent magnetic field. When a massive sound 00:10:25.740 --> 00:10:28.559 wave hits the diaphragm, it violently pushes 00:10:28.559 --> 00:10:30.620 the coil back and forth through the magnetic 00:10:30.620 --> 00:10:33.139 field. It's essentially a microscopic power plant. 00:10:33.460 --> 00:10:36.500 Exactly. Just like a giant hydroelectric dam 00:10:36.500 --> 00:10:39.460 spins a turbine inside a magnet to generate a 00:10:39.460 --> 00:10:42.399 city's power, your voice acts as the wind, pushing 00:10:42.399 --> 00:10:45.299 that tiny coil through a magnet, literally generating 00:10:45.299 --> 00:10:47.779 a brand new electrical current out of thin air. 00:10:47.909 --> 00:10:49.889 It generates its own voltage entirely, which 00:10:49.889 --> 00:10:52.789 is why it never needs phantom power. It is completely 00:10:52.789 --> 00:10:54.909 self -sufficient. And here's where it gets really 00:10:54.909 --> 00:10:57.009 interesting. Because of how a dynamic mic is 00:10:57.009 --> 00:10:59.129 built, with a membrane attached to a coil sitting 00:10:59.129 --> 00:11:01.909 in a magnet, it is functionally identical to 00:11:01.909 --> 00:11:04.669 a loudspeaker. It is the exact same machinery, 00:11:04.850 --> 00:11:07.029 just operating in reverse. Yeah, the principle 00:11:07.029 --> 00:11:09.950 of reciprocity applies perfectly here. A speaker 00:11:09.950 --> 00:11:12.350 takes an electrical current, pushes a membrane, 00:11:12.730 --> 00:11:15.909 and moves air to create sound. A dynamic mic 00:11:16.110 --> 00:11:18.909 takes moving air, pushes a membrane and creates 00:11:18.909 --> 00:11:22.059 electrical current. Because the physics are identical, 00:11:22.500 --> 00:11:25.480 you can literally wire a speaker in reverse and 00:11:25.480 --> 00:11:27.759 use it to capture sound. Which blew my mind because 00:11:27.759 --> 00:11:29.759 the source notes that audio engineers actually 00:11:29.759 --> 00:11:32.100 do this on purpose. There's a device called the 00:11:32.100 --> 00:11:34.840 Yamaha Subkick. It is literally a six and a half 00:11:34.840 --> 00:11:38.039 inch speaker woofer, the exact kind you'd find 00:11:38.039 --> 00:11:40.720 in a home stereo mounted inside a drum shell. 00:11:40.759 --> 00:11:43.000 It looks crazy in the studio. And engineers place 00:11:43.000 --> 00:11:45.399 it right in front of a kick drum. Because the 00:11:45.399 --> 00:11:47.820 speaker membrane is so massive and heavy, it 00:11:47.820 --> 00:11:49.970 physically cannot move fast enough to pick up 00:11:49.970 --> 00:11:52.409 the high -pitched sounds of the cymbals. So it 00:11:52.409 --> 00:11:55.429 acts as a natural physical acoustic filter only 00:11:55.429 --> 00:11:58.070 picking up those massive low -frequency thumps. 00:11:58.230 --> 00:12:00.490 It's literally just a speaker listening instead 00:12:00.490 --> 00:12:02.350 of shouting. It's a brilliant hack of physical 00:12:02.350 --> 00:12:04.909 mass. Now the third of the big three technologies 00:12:04.909 --> 00:12:08.370 also introduced around 1923 is the ribbon microphone. 00:12:08.509 --> 00:12:11.610 The fragile ones. Very fragile. It uses a magnetic 00:12:11.610 --> 00:12:14.169 field like the dynamic mic but instead of a heavy 00:12:14.169 --> 00:12:17.309 coil it suspends an incredibly thin corrugated 00:12:17.309 --> 00:12:20.070 strip of aluminum ribbon right between the magnets. 00:12:20.450 --> 00:12:22.649 And these are notorious for being the most fragile 00:12:22.649 --> 00:12:24.549 pieces of equipment in a studio. Oh, without 00:12:24.549 --> 00:12:27.509 question. Because the ribbon is mere microns 00:12:27.509 --> 00:12:31.450 thick, it has almost zero mass. This means it 00:12:31.450 --> 00:12:33.590 responds to the raw velocity of the air particles 00:12:33.590 --> 00:12:36.230 moving past it rather than just the pressure. 00:12:36.750 --> 00:12:39.570 It captures a uniquely smooth, highly natural 00:12:39.570 --> 00:12:42.990 sound. But older vintage ribbon mics could literally 00:12:42.990 --> 00:12:45.409 be torn to shreds by a careless gust of wind. 00:12:45.629 --> 00:12:49.460 Wow. Just a strong breeze. Literally. And if 00:12:49.460 --> 00:12:51.620 you accidentally routed that 48 volt phantom 00:12:51.620 --> 00:12:53.580 power we talk about into a vintage ribbon mic, 00:12:53.960 --> 00:12:55.600 the sudden jolt of electricity could stretch 00:12:55.600 --> 00:12:58.779 or snap the metal ribbon instantly. Ouch. So 00:12:58.779 --> 00:13:00.700 we've engineered mics that won't break and mics 00:13:00.700 --> 00:13:03.340 that sound incredibly lifelike. But there's a 00:13:03.340 --> 00:13:05.980 glaring problem. If you put that perfectly engineered 00:13:05.980 --> 00:13:08.500 microphone in a room with a terrible echo or 00:13:08.500 --> 00:13:11.039 on a live stage with screaming fans and blaring 00:13:11.039 --> 00:13:13.379 amplifiers, it's going to beautifully capture 00:13:13.379 --> 00:13:16.690 all that garbage, too. Exactly. Mastering the 00:13:16.690 --> 00:13:18.870 internal tech was really only half the battle. 00:13:19.889 --> 00:13:21.850 Engineers had to figure out how to control the 00:13:21.850 --> 00:13:24.470 invisible geometry around the mic to tell it 00:13:24.470 --> 00:13:27.309 what to ignore. This introduces the concept of 00:13:27.309 --> 00:13:29.889 polar patterns. These are the invisible three 00:13:29.889 --> 00:13:31.970 -dimensional shapes of sensitivity surrounding 00:13:31.970 --> 00:13:34.929 a microphone capsule. They basically dictate 00:13:34.929 --> 00:13:37.519 the spatial awareness of the device. Let's start 00:13:37.519 --> 00:13:39.960 with the Bassline Omnidirectional. Right. Just 00:13:39.960 --> 00:13:43.039 like it sounds, it hears a perfect 360 -degree 00:13:43.039 --> 00:13:45.879 sphere around the capsule. And the source notes 00:13:45.879 --> 00:13:48.539 that Omnidirectional mics offer the purest sound 00:13:48.539 --> 00:13:51.200 with the lowest coloration, and they can capture 00:13:51.200 --> 00:13:54.340 incredibly deep bass all the way down to 20 Hz, 00:13:54.720 --> 00:13:57.179 because they are purely sensing changes in raw 00:13:57.179 --> 00:13:59.460 air pressure from any angle. They don't have 00:13:59.460 --> 00:14:02.259 to play any complex acoustic tricks or use physical 00:14:02.259 --> 00:14:05.100 blockages to filter sound, so the frequency response 00:14:05.100 --> 00:14:07.309 is naturally very flat. and true to reality. 00:14:07.509 --> 00:14:08.850 Okay, but I have to push back on this. Sure. 00:14:09.009 --> 00:14:11.789 If omnidirectional microphones provide the absolute 00:14:11.789 --> 00:14:14.610 purest sound, the most accurate bass, and basically 00:14:14.610 --> 00:14:17.129 no distortion, why don't we just use them for 00:14:17.129 --> 00:14:19.070 absolutely everything? Well, we run headfirst 00:14:19.070 --> 00:14:21.570 into the messy reality of the spaces we live 00:14:21.570 --> 00:14:24.480 in. Yes, an omnimike is mathematically pure, 00:14:24.840 --> 00:14:27.059 but imagine you were recording a singer in a 00:14:27.059 --> 00:14:30.940 small square room with bare walls. An omnidirectional 00:14:30.940 --> 00:14:33.360 mic will record the singer perfectly, but it 00:14:33.360 --> 00:14:36.379 will also perfectly capture every single ugly 00:14:36.379 --> 00:14:38.720 metallic echo bouncing off the walls right behind 00:14:38.720 --> 00:14:42.879 it. Ahh. Or consider a live concert stage. If 00:14:42.879 --> 00:14:45.120 the lead singer's microphone is omnidirectional, 00:14:45.519 --> 00:14:47.879 it will pick up the drums, the guitar amps, and 00:14:47.879 --> 00:14:50.659 most dangerously, the stage monitor is pointing 00:14:50.659 --> 00:14:52.879 directly back at the singer. Which creates the 00:14:52.879 --> 00:14:55.600 dreaded feedback loop. The mic hears the speaker, 00:14:55.940 --> 00:14:57.879 amplifies it, plays it out the speaker, the mic 00:14:57.879 --> 00:15:00.159 hears it again, and in a fraction of a second, 00:15:00.779 --> 00:15:02.700 everyone in the audience is covering their ears 00:15:02.700 --> 00:15:05.700 from that piercing screech. It's terrible. To 00:15:05.700 --> 00:15:07.820 solve that... engineers had to figure out how 00:15:07.820 --> 00:15:10.360 to make microphones that only listen in one specific 00:15:10.360 --> 00:15:12.620 direction. And the foundation of directional 00:15:12.620 --> 00:15:15.059 listening is the figure eight, or bi -directional 00:15:15.059 --> 00:15:17.559 pattern. Ribbon microphones actually do this 00:15:17.559 --> 00:15:19.720 naturally just by their physical design. Wait, 00:15:19.720 --> 00:15:21.059 let me see if I can picture this based on what 00:15:21.059 --> 00:15:23.960 we just talked about. The ribbon is suspended 00:15:23.960 --> 00:15:26.620 between magnets, meaning it's totally open to 00:15:26.620 --> 00:15:29.059 the air on the front and the back, but the sides 00:15:29.059 --> 00:15:31.120 are blocked by the magnets themselves. Right. 00:15:31.360 --> 00:15:33.679 So if a sound wave comes from the exact left 00:15:33.679 --> 00:15:36.980 or right, It hits both the front and back of 00:15:36.980 --> 00:15:39.799 the ribbon at the exact same millisecond. That 00:15:39.799 --> 00:15:42.259 is exactly what happens. It creates a state of 00:15:42.259 --> 00:15:45.080 acoustic tug of war. The air pressure pushes 00:15:45.080 --> 00:15:47.500 on the front and the back equally. at the exact 00:15:47.500 --> 00:15:50.620 same time. The forces cancel each other out completely, 00:15:50.620 --> 00:15:53.039 and the ribbon doesn't move a single millimeter. 00:15:53.200 --> 00:15:55.779 That is incredibly elegant. It's mathematically 00:15:55.779 --> 00:15:58.179 blind to the sides. You could place a figure 00:15:58.179 --> 00:16:00.679 -eight mic right above a drum kit, point the 00:16:00.679 --> 00:16:02.460 blind sides at the loudest cymbals, and it will 00:16:02.460 --> 00:16:04.940 just effectively ignore them. It's a lifesaver 00:16:04.940 --> 00:16:06.919 in the studio. But the sources highlight that 00:16:06.919 --> 00:16:09.240 the most important shape in all of audio engineering 00:16:09.240 --> 00:16:12.340 is the cardioid pattern. Cardioid meaning heart 00:16:12.340 --> 00:16:15.279 -shaped. It listens closely to the front, captures 00:16:15.279 --> 00:16:18.299 a little bit on the sides, and completely rejects 00:16:18.299 --> 00:16:20.639 sound coming from the rear. And this is the pattern 00:16:20.639 --> 00:16:23.480 that completely revolutionized live sound. It's 00:16:23.480 --> 00:16:26.799 why the Shure SM58 is the undisputed king of 00:16:26.799 --> 00:16:29.659 live vocals. The singer sings into the front 00:16:29.659 --> 00:16:32.539 of the heart shape, and the stage monitors blasting 00:16:32.539 --> 00:16:34.679 at the back of the microphone just fall into 00:16:34.679 --> 00:16:38.340 the rejection zone. No feedback. But how do you 00:16:38.340 --> 00:16:40.500 actually create a heart -shaped listening zone 00:16:40.500 --> 00:16:43.269 out of thin air? It involves an elegant trick 00:16:43.269 --> 00:16:46.870 of physics called superposition. Engineers designed 00:16:46.870 --> 00:16:49.070 the capsule to electronically or acoustically 00:16:49.070 --> 00:16:51.789 combine an omnidirectional pattern with a figure 00:16:51.789 --> 00:16:54.330 8 pattern. You lay those two invisible shapes 00:16:54.330 --> 00:16:56.450 directly over each other. Hold on, I need an 00:16:56.450 --> 00:16:58.750 explanation here. You're saying a positive signal 00:16:58.750 --> 00:17:01.070 from one pattern and a negative signal from another 00:17:01.070 --> 00:17:03.210 combine and the sound just completely disappears. 00:17:03.629 --> 00:17:06.450 How does that work in the actual air? Okay, imagine 00:17:06.450 --> 00:17:09.069 two identical water waves in a pool crashing 00:17:09.069 --> 00:17:11.750 into each other. If the high peak of one wave 00:17:11.750 --> 00:17:13.950 perfectly hits the low trough of the other waves, 00:17:14.309 --> 00:17:16.869 the forces neutralize and the water goes completely 00:17:16.869 --> 00:17:20.130 flat. Like they just erase each other. Exactly. 00:17:20.549 --> 00:17:22.710 Engineers are doing that, but with invisible 00:17:22.710 --> 00:17:25.269 sound pressure. The positive signal from the 00:17:25.269 --> 00:17:27.569 front of the figure 8 adds to the omni, boosting 00:17:27.569 --> 00:17:30.049 the front's sensitivity. But the rear of a figure 00:17:30.049 --> 00:17:33.650 8 is out of phase. It's a negative trough. When 00:17:33.650 --> 00:17:35.769 that negative trough hits the positive peak of 00:17:35.769 --> 00:17:38.230 the omni signal at the back, they cancel each 00:17:38.230 --> 00:17:41.660 other out entirely. Flat water. Absolute silence 00:17:41.660 --> 00:17:44.200 at the rear of the mic. That is genuinely brilliant 00:17:44.200 --> 00:17:47.140 engineering. What's fascinating here is the physical 00:17:47.140 --> 00:17:49.279 side effect of this directional listening, which 00:17:49.279 --> 00:17:51.200 is a phenomenon called the proximity effect. 00:17:51.319 --> 00:17:54.440 Because cardioid microphones rely on these complex 00:17:54.440 --> 00:17:56.500 pressure gradients to create their directionality, 00:17:57.000 --> 00:17:58.920 whenever a sound source gets extremely close 00:17:58.920 --> 00:18:00.940 to the capsule, like within a few centimeters, 00:18:01.440 --> 00:18:03.660 the physics of the gradient shift, causing a 00:18:03.660 --> 00:18:06.359 massive artificial boost in the lowest bass frequencies. 00:18:06.740 --> 00:18:10.039 Oh, that explains the classic radio DJ voice. 00:18:10.180 --> 00:18:12.940 That's the one. That's why podcasters and broadcasters 00:18:12.940 --> 00:18:15.940 always sound so incredibly deep, booming, and 00:18:15.940 --> 00:18:18.200 resonant. They are getting right up on the mic, 00:18:18.500 --> 00:18:20.500 intentionally triggering that physical proximity 00:18:20.500 --> 00:18:22.700 effect. to boost their bass. They are playing 00:18:22.700 --> 00:18:24.920 the physics of the capsule like a musical instrument. 00:18:25.339 --> 00:18:28.440 They absolutely are. Now, if you need extreme 00:18:28.440 --> 00:18:31.019 directionality, say, recording dialogue on a 00:18:31.019 --> 00:18:32.980 movie set where the boom pole is 10 feet away 00:18:32.980 --> 00:18:35.920 from the actor, you use a shotgun microphone. 00:18:36.299 --> 00:18:39.000 These are those long, futuristic metal wands, 00:18:39.119 --> 00:18:41.400 and the way they narrow their focus is amazing. 00:18:41.539 --> 00:18:44.480 They use an interference tube. The actual microphone 00:18:44.480 --> 00:18:47.200 capsule is hidden way down at the base of a long 00:18:47.200 --> 00:18:50.259 tube with tiny slots cut off. all down the sides, 00:18:50.839 --> 00:18:53.099 sound coming straight from the actor goes cleanly 00:18:53.099 --> 00:18:55.799 right down the barrel to the mic. But ambient 00:18:55.799 --> 00:18:58.039 distracting sound from the side enters through 00:18:58.039 --> 00:19:00.299 those different slots. And because the side noise 00:19:00.299 --> 00:19:02.339 enters those slots at different physical distances 00:19:02.339 --> 00:19:04.940 along the tube, the sound waves reach the capsule 00:19:04.940 --> 00:19:06.940 at slightly different times. They arrive out 00:19:06.940 --> 00:19:10.160 of phase. Returning to our water analogy, the 00:19:10.160 --> 00:19:12.200 peaks and troughs crash into each other inside 00:19:12.200 --> 00:19:14.380 the tube, canceling each other out before they 00:19:14.380 --> 00:19:16.240 even hit the diaphragm. Of course, if you're 00:19:16.240 --> 00:19:18.519 using a shotgun mic outside on a film set, you 00:19:18.519 --> 00:19:21.099 have to deal with wind. And the source mentions 00:19:21.099 --> 00:19:23.619 some of the best terminology in the entire audio 00:19:23.619 --> 00:19:26.299 industry for wind screens. Because wind isn't 00:19:26.299 --> 00:19:29.079 really sound, right? It's a massive, chaotic, 00:19:29.259 --> 00:19:32.579 physical blast of air that causes violent turbulence 00:19:32.579 --> 00:19:36.599 against the mic capsule. To stop it, engineers 00:19:36.599 --> 00:19:39.819 put the mic inside large, pill -shaped foam cages 00:19:39.819 --> 00:19:43.279 called blimps or zeppelins. And if the wind is 00:19:43.279 --> 00:19:45.910 really howling, they cover the blimp in a thick 00:19:45.910 --> 00:19:49.390 layer of artificial fur. The film industry affectionately 00:19:49.390 --> 00:19:52.890 refers to these furry covers as dead cats or 00:19:52.890 --> 00:19:55.609 for the smaller microphones on top of consumer 00:19:55.609 --> 00:19:58.630 cameras, dead kittens. It looks absurd. It looks 00:19:58.630 --> 00:20:00.849 exactly like you strapped a fuzzy gray animal 00:20:00.849 --> 00:20:03.049 to the end of a pole. It looks ridiculous. But 00:20:03.049 --> 00:20:04.910 the physics are highly effective. You have a 00:20:04.910 --> 00:20:07.269 massive gust of wind hitting the mic. The thousands 00:20:07.269 --> 00:20:09.829 of individual fur fibers break up that heavy 00:20:09.829 --> 00:20:13.589 blunt force wind into millions of tiny microvortices. 00:20:14.210 --> 00:20:16.730 Microvortices. Right. It converts the heavy turbulence 00:20:16.730 --> 00:20:19.650 into microscopic friction, absorbing the kinetic 00:20:19.650 --> 00:20:22.549 energy completely silently without blocking the 00:20:22.549 --> 00:20:24.809 actual acoustic sound waves of the actors talking. 00:20:25.109 --> 00:20:27.789 So we've mastered high fidelity studio recording, 00:20:28.049 --> 00:20:30.390 we've conquered feedback on live stages, and 00:20:30.390 --> 00:20:32.730 we can mathematically filter out wind on a film 00:20:32.730 --> 00:20:37.450 set. But human curiosity never stops. Once we 00:20:37.450 --> 00:20:40.230 understood the baseline physics, scientists started 00:20:40.230 --> 00:20:42.849 pushing audio capture into extreme environments 00:20:42.849 --> 00:20:45.569 where a standard moving diaphragm would be completely 00:20:45.569 --> 00:20:47.609 useless. I mean, what do you do if the thing 00:20:47.609 --> 00:20:49.269 you want to hear doesn't make a sound in the 00:20:49.269 --> 00:20:51.470 air at all? That's where contact microphones 00:20:51.470 --> 00:20:54.079 come in. Instead of picking up fluctuating air 00:20:54.079 --> 00:20:56.880 pressure, they detect solid, physical vibrations. 00:20:57.440 --> 00:20:59.640 The transducer plate is placed directly against 00:20:59.640 --> 00:21:01.859 an object. And the examples in the source are 00:21:01.859 --> 00:21:04.619 stunning. Contact mics are so hypersensitive 00:21:04.619 --> 00:21:06.480 they have been used by researchers to record 00:21:06.480 --> 00:21:09.200 the literal footsteps of ants and the muscular 00:21:09.200 --> 00:21:11.900 heartbeat of a snail. It fundamentally shifts 00:21:11.900 --> 00:21:14.859 what we even consider to be sound. We also have 00:21:14.859 --> 00:21:16.859 environments where metal and electricity are 00:21:16.859 --> 00:21:19.579 actively dangerous. Think about the inside of 00:21:19.579 --> 00:21:22.480 a hospital MRI machine. The magnetic field is 00:21:22.480 --> 00:21:25.460 so massive that a dynamic or ribbon mic would 00:21:25.460 --> 00:21:28.660 be instantly destroyed. Or worse, the magnets 00:21:28.660 --> 00:21:31.380 would turn the metal casing into a lethal projectile. 00:21:31.519 --> 00:21:33.759 Which you definitely do not want in a hospital. 00:21:33.980 --> 00:21:36.599 No. So to solve that they invented the fiber 00:21:36.599 --> 00:21:39.680 optic microphone. There are zero metal or electrical 00:21:39.680 --> 00:21:42.130 parts in the capsule at all. It shoots a tiny 00:21:42.130 --> 00:21:44.869 laser down a glass optical fiber, bounces the 00:21:44.869 --> 00:21:47.049 light off a reflective diaphragm, and sends it 00:21:47.049 --> 00:21:49.549 back up sick on fiber. When sound moves that 00:21:49.549 --> 00:21:51.730 diaphragm, it changes the intensity of the reflected 00:21:51.730 --> 00:21:54.150 light. That's so clever. A computer down a hall 00:21:54.150 --> 00:21:56.130 reads the light fluctuations and turns it back 00:21:56.130 --> 00:21:59.589 into audio. Complete 100 % immunity to magnetic 00:21:59.589 --> 00:22:02.099 fields. If you want to go a step further and 00:22:02.099 --> 00:22:05.200 eliminate the physical diaphragm entirely, you 00:22:05.200 --> 00:22:07.859 move into the realm of pure laser microphones. 00:22:08.579 --> 00:22:11.099 You can point an infrared laser at a distant 00:22:11.099 --> 00:22:14.079 window pane across the street, measure the microstopic 00:22:14.079 --> 00:22:16.500 vibrations of the solid glass caused by the people 00:22:16.500 --> 00:22:19.319 talking inside the room, and convert those vibrations 00:22:19.319 --> 00:22:22.250 back into perfectly intelligible speech. It's 00:22:22.250 --> 00:22:24.710 straight out of a spy movie. It really is. The 00:22:24.710 --> 00:22:26.930 source even details an experimental laser mic 00:22:26.930 --> 00:22:29.170 that bounces light off a moving stream of smoke 00:22:29.170 --> 00:22:32.890 or vapor in free air. It reads the acoustic disturbances 00:22:32.890 --> 00:22:35.869 in the smoke itself. So what does this all mean? 00:22:35.990 --> 00:22:38.390 If we can literally read the vibration of smoke 00:22:38.390 --> 00:22:40.289 in the air or pull a conversation off a window 00:22:40.289 --> 00:22:42.670 pane a mile away, doesn't this mean that true 00:22:42.670 --> 00:22:45.210 privacy is essentially obsolete? If we connect 00:22:45.210 --> 00:22:47.609 this to the bigger picture, it means our definition 00:22:47.609 --> 00:22:50.569 of the microphone has to radically evolve. They 00:22:50.569 --> 00:22:53.170 began in the 1800s as simple telecommunication 00:22:53.170 --> 00:22:55.630 tools, a brute force way to shout across long 00:22:55.630 --> 00:22:59.190 distance. But today, microphones act as literal 00:22:59.190 --> 00:23:02.170 sensory extensions of the human body. They allow 00:23:02.170 --> 00:23:04.529 us to perceive the microscopic reality of an 00:23:04.529 --> 00:23:07.250 ant's footprint, or safely listen inside lethal 00:23:07.250 --> 00:23:09.930 radiation zones. They have completely surpassed 00:23:09.930 --> 00:23:11.809 the biological limitations of the human ear. 00:23:11.950 --> 00:23:14.890 The ultimate proof of that is the experimental 00:23:14.890 --> 00:23:17.190 plasma microphone. It doesn't use a membrane, 00:23:17.470 --> 00:23:20.130 or glass, or lasers. It uses a literal electric 00:23:20.130 --> 00:23:23.089 arc of ionized gas. Sound waves hit the plasma, 00:23:23.549 --> 00:23:25.750 change the local air pressure, which alters the 00:23:25.750 --> 00:23:27.509 temperature and the electrical conductance of 00:23:27.509 --> 00:23:30.269 the gas itself. It's capturing sound with a controlled 00:23:30.269 --> 00:23:32.789 lightning bolt. It's a long, long way from a 00:23:32.789 --> 00:23:34.950 needle bouncing in a cup of sulfuric acid. It 00:23:34.950 --> 00:23:37.410 is a profound evolution of our mastery over physics. 00:23:37.680 --> 00:23:40.200 So, the next time you are sitting at your desk 00:23:40.200 --> 00:23:42.220 and you reach out to click that unmute button 00:23:42.220 --> 00:23:44.819 on your morning video call, or you put on your 00:23:44.819 --> 00:23:47.099 favorite headphones to listen to a perfectly 00:23:47.099 --> 00:23:50.599 crisp, intimate vocal on a classic album, take 00:23:50.599 --> 00:23:53.420 a second, you are benefiting from over a century 00:23:53.420 --> 00:23:56.519 of wild, dangerous, and brilliant engineering 00:23:56.519 --> 00:24:00.539 from acid baths and crushed carbon to tiny power 00:24:00.539 --> 00:24:03.279 plants, heart -shaped invisible listening zones, 00:24:03.500 --> 00:24:06.119 and artificial fur. It really leaves you with 00:24:06.119 --> 00:24:08.039 an incredibly interesting question about where 00:24:08.039 --> 00:24:11.259 this trajectory goes next. If we have successfully 00:24:11.259 --> 00:24:13.579 turned lightning bolts, lasers, and fiber optics 00:24:13.579 --> 00:24:16.220 into microphones, what happens when we finally 00:24:16.220 --> 00:24:19.480 crack neural interfaces? In the not -so -distant 00:24:19.480 --> 00:24:21.779 future, we might bypass the physical air pressure 00:24:21.779 --> 00:24:24.700 of sound entirely. The microphone might cease 00:24:24.700 --> 00:24:26.500 to be an external piece of hardware sitting on 00:24:26.500 --> 00:24:29.200 your desk and instead become a direct brain -to 00:24:29.200 --> 00:24:31.900 -digital telepathic transducer. No diaphragm. 00:24:32.000 --> 00:24:34.579 No moving parts. Just pure thought converted 00:24:34.579 --> 00:24:36.960 directly into a signal. Now that is something 00:24:36.960 --> 00:24:37.599 to think about.