It's important to know the impact of even a single sample delay. It's surprising how much a delay of a 44,000 100th of a second can make on your signal, and it turns out that around us all over the place we're dealing with these short delays. And we're dealing with the phase cancellation that is imposed with those delays. So in this next video we're going to look at the impact of taking a very short delay, and then what happens when we get longer and longer delays. We'll start with just simple white noise. We'll just equal the noise, we'll just equal amplitude across the frequency spectrum. And we'll add slight delays mixed back with itself and we'll see how spectrum changes based on that. At first it'll look like just a deep notch in the frequency spectrum and eventually we'll get a series of related notches that are harmonically related, which we know is comb filtering and then eventually we get to the point where we hear a delay. We get to that point, we'll switch to using more percussive sounds and just explore as we increase that delay, kind of what it sounds like. And I just want you, as we're doing this, to kind of relate it back to what you hear in nature because delays are around us all over the place. And just like the dynamic effects, you have to kind of learn to hear them and learn to recognize them. You want to start to learn and recognize the sound of delay effect. And this idea of comb filtering is a really important one because it's always giving us trouble when we are recording. Remember a delay is a reflection off a surface and every time you put a microphone in front of an object, you have to be careful of other surfaces around you because the sound from that object or the sound from that source will bounce off all these other objects and hit that microphone as well. So when you look at delay effect, it's also related to what happens when we record. And these kind of deep notches, play less in recording, we call it faze g/ cancellation, and cone filtering. So we have to be very careful with that. So in this next video we're going to look at spectrum of delay. What happens as we increase delay time, and I'd like you, just to, remember, to relate that back to what you hear in the real world all around you. We'll start our examination of the delay spectrum with the shortest possible delay, a single sample. I'm going to demonstrate this by taking two audio files, which are the exact same audio file and both white noise. White noise is equal energy across the frequency range. So these two audio files which are exactly the same are being placed on two separate tracks and are being added together here before they're sent to the displays you see in front of you. I am then going to delay one of those two copies by a single sample and we're going to see how big an impact that has on the overall spectrum. And then we'll try to use longer and longer delays from there. So, here is white noise. Again, this is two of the same exact white noise audio files played together. And then I'll be delaying one of the copies by a tiny increment. So there is white noise. You see equal energy across the frequency range. Now, I'm going to delay one of the copies. So that was a single sample of delay. And you can see right here in the sonogram how we have a major cut in the high end with a single-sample delay. Let me try two samples. Two samples of delay gives us a serious notch, right around 12 K. That's two samples, that two 48 thousandths of a second. It's amazing how a small delay can have such an impact. Let's try more. That's three samples, four, five, six, seven [SOUND] That's 48 samples of delay and we start really seeing the idea of a comb filter. And a calm filter's called that because it does the series of notches. Now it's very important that you start being able to hear the sound of calm filtering because it's all around you. Let me go a little further [SOUND] . This demonstration shows us clearly the impact of combining a sound with a delayed copy of itself. And this happens when you're recording. Imagine I'm recording an instrument. And I have a microphone in front of that instrument. The sound goes from the instrument, arrives at the microphone. But the sound also bounces off a nearby flat surface and arrives at the microphone a little bit later. That is combining a sound with a delayed copy of itself, just like we've done here. And, there is definite possibility you'll get comb filtering in your recordings, if you have this situation. So this is why we need to be so careful about any nearby flat surfaces when recording, because we will get comb filtering, and it's probably going to have a negative impact on our sound. Now that we want to move to longer and longer delay times it's going to be useful to switch to a percussive sound so we can hear that transient and we can note when that transient becomes doubled and when it sounds like two separate hits. Again, we're taking the same exact sound and just delaying one of them. Here we go. Here's a snare sound with no delay. [NOISE] I'm going to slowly bring up the delay time. Now we're at a one millisecond delay. Two milliseconds. Three milliseconds. Four milliseconds. [SOUND] Five milliseconds. [SOUND] So over that entire range up to five milliseconds we've been hearing that shifting comb filtering sound. I'm now continue to raise the delay time up even further. [SOUND] Six milliseconds, seven milliseconds, nine. Ten miliseconds. It's starting to sound buzzy and I'm almost noticing a pitch in there somehow. Let's continue on. [SOUND] [MUSIC] Eighteen milliseconds and it feels a flan/g. [NOISE] And by the time I'm at 36 milliseconds here, it really feels like I have two different hits. I notice the delay as two separate events. In this final exploration of the delay spectrum, we're going to take a different approach. This time, I'll start with a very simple clicky sound. Let's hear it. [SOUND]. I'm going to run that sound through a simple delay. And I'm going to have the feedback all the way up. And we're going to see that very short delay times actually create a pitch. And in fact, throughout this entire week, we're going to going to be exploring the curious relationship between delay and frequency. So, let's try this out and see what happens. We'll start with our sound, it's kind of clicky and it's repeating. [NOISE] Now I'm going to engage the delay, it's 100% wet, the feedback is all the way down and my delay time is one millisecond. I'm now going to increase the feedback. [SOUND] As we increase the feedback a pitch will emerge. [SOUND] because our sense of frequency is our perception of things repeating very fast [SOUND] And what we've done with this delay is create very quick repetitions. So fast that we perceive it as a pitch. I'm now going to increase the delay time. Right now it's on 1.0 millisecond and I'll increase it. [SOUND] 1.1 milliseconds. [SOUND] [MUSIC] [SOUND] Eventually we get to the point where we start hearing it as separate Attacks as we hear as a rhythm. This kind of a exploration it probes the edges of our perception, at what point does the delay become pitch. How is the delay and frequency intertwined. What are the edges of human perception and how can that be explored musically. This kind of Interactions between delay in frequency and delay in filtering, are explored heavily throughout audio effects. We're going to find these characteristics show up in our chorus phasers, falangers short delays, long delays, and reverbs And our filters. It's an incredibly important spectrum, this delayed spectrum. And honestly its kind of difficult to kind of wrap the brain around. How are all these interactions really working,, and how can we use them musically?
