How to Choose a Microphone: A Guide to Using Them

1. Introduction/ Promo: Microphones come in many variations and shapes, sizes and styles. It is important that we choose the right microphone for the situation we're going to be using it in. Using the wrong microphone in the wrong situation, can mean that you're going to get really bad audio, or even worse, you'll damage your equipment. That's why it's important we learn some of the basic fundamentals about microphones, so we can make the right decision. I'm Ryan, and I'll be taking you through this course. I'm a sound engineer that's got experience in live sound, studio recording, and location recording as well for film and TV. In this course, we're going to look at some examples of different types and styles of microphones, and you're going to be able to listen to them so you can understand what situation would be best to use them in. I'm also going to be covering some of the technical language you might see when looking at microphones: such as what is the frequency response, what is the polar pickup pattern of a microphone? We'll explain how you can use that language to really guide your understanding of when and where to use those different types of microphone. As well as briefly talking about how microphones work. We'll also look at some of the accessories to use with microphones, such as how to control wind or plosive sounds from dialogue. If you are going to be using a microphone for recording a voice-over, a podcast, an interview, an instrument, whatever situation you are going to be in. This course will give you the knowledge to make a better decision when it comes to choosing a microphone, so you can get the best results. Let's jump straight into the first session and talk briefly about how microphones work. 2. How Microphones Work: Sound is a fluctuation in the air pressure around us. Sound waves. A microphone is the way that we can convert that energy into electrical energy. All microphones have a component in them called a diaphragm, and that works a little bit like your eardrum. When the sound waves hit the diaphragm, it vibrates and changes it into electrical energy. Then the energy travels down a microphone cable, where it's converted into electrical energy until it reaches its destination, say a computer or a mixer, and then it's changed into an audio signal. It works similar to having a conversation with someone. You speak, and the sound wave travels through the air to the other person's ear. The eardrum then vibrates and then interprets that signal. Then your brain decodes that into the message of sound. Different microphones have different shaped and sized diaphragms, which means they all pick up and interpret the sound in different ways. That's why it's important that we choose the right microphone for what application we're going to be using it in. When using a microphone, it's important to understand something called the signal-to-noise ratio. It helps us understand the difference between the desired signal, in this case, my voice, to the unwanted noise of that situation. In this case, it would be the background sound. We'll use this microphone here as an example to show you that. If I'm talking into this microphone now, you can hear my voice clearly, that's the signal. You should be able to just about hear the background sound. Remember that's the noise which is unwanted. But as I move back away from the microphone, the signal becomes further away and the background noise becomes louder because we have to increase the whole volume of that sound now to understand what I'm saying and to have my level high enough. That's why we always want a high signal to a low noise ratio. Some microphone manufacturers will display this information on their technical pages on the websites or in the manuals. This is normally seen as S-N or SNR. It's normally measured in decibels SPL. Just to recap the signal-to-noise ratio, the larger the number, the better the results you're going to get. In the next session, we're going to look at the two main types of microphone, and we'll listen to them as well so you can understand when it'd be best to use them. 3. Types of Microphones: There are many types of microphones to choose from, and it's important that we choose the right one for the right situation because if not, you are going to get bad audio, and you could even break the equipment. In this section, we're going to look at the two main types of microphone, which are dynamic and condenser. There are other types of microphone out there such as ribbon, crystal, but these are used more in quite niche applications. Do some further research onto those different microphones. But in this section, we'll just cover the main two. First we'll talk a little bit about dynamic microphones. These are the most popular type of microphones, as they are really good all rounders. They're quite cheap, they're very durable, and the diaphragms are less sensitive to damage so they tend to last a little bit longer than other types of microphone. They're aimed more at live situations, but also have their place in the studio as well. The reason why they're better in live situations is because the diaphragm is a lot smaller than other types of microphone. If you're a singer on a stage, because the microphone's less sensitive than other types, the microphone's only going to pick up a small amount of sound just in front of the microphone capsule. That means it's not going to be bringing in any of the unwanted sound around, such as a guitarist, a drummer, or sounds coming back from the speakers, which will create feedback. Dynamic microphone used in a live application, means that the signal to noise ratio is going to be best. Two of the most popular used dynamic microphones are the Shure SM58 and the Shure SM57. We'll have a little lesson to those microphones now. This is the Shure SM58 vocal live microphone. It's one of the most popular microphones used amongst bands all over the world, and like I said, it's mainly used for vocals in a live situation. This is the Shure SM57. It's sometimes used as a live vocal mic, but it's also used mainly for things like parts on a drum key or for recording instruments through speakers such as a guitar, through an amplifier. The second most popular microphone is a condenser, which are mainly used in studio applications, because the diaphragm is much more sensitive than the dynamic microphones. Because these are sensitive to sound, it gives really good quality professional results. You'll often see these microphones used for voice-over, for vocals in a studio, acoustic guitar, dialogue for film and TV. The downside of these microphones really is that they can only be used in quite a controlled setting. You wouldn't really use condenser microphones in a live situation, because a lot of the feedback from the surroundings would come back into the capsule and create feedback. Another main difference between the dynamic and condenser microphone is that they require something called 48 volt phantom power. This is because condenser microphones are a lot more powerful than dynamic microphones, we need to provide the microphone with additional power. Most sound mixes, sound cards, and recorders, will all have that as an in-built feature, and you'll usually see that as a button called plus 48 volts. We'll look at an example of one of these microphones, which is a Rode NT2A. This is an example of how the Rode NT2A sounds. It's a large diaphragm studio condenser microphone. It's really good for getting that crystal clear, creamy voice that's often associated with things like voice-overs and podcasts. Hopefully now you understand the two main types of microphone; dynamic and condenser. In the next session, we're going to look at another element to the microphones that we need to be looking at, and that's the polar pick up pattern. 4. Polar Pick Up Patterns: When a manufacturer goes through the process of designing a microphone, they ask the simple question of, what will the microphone actually be used for? When you are choosing a microphone to use, you must also ask that question, because that will determine what polar pickup pattern the microphone has. The polar pickup pattern of a microphone determines where the microphone is picking up the sound from. We have to understand something when using a microphone, what being on axis is and what being off axis is. If we're on axis, where within the polar pickup pattern of the microphone, if we're off axis, we're outside of that pickup pattern. Let's have a look at the most common pickup patterns and we'll listen to a few examples of microphones that have the different patterns to really understand when it's best to use them. The most common type of pickup pattern is cardioid, and it's called that because of the shape when you view it from a diagram format. The shape is a heart that comes out from the capture of the microphone around the front. That means it's more sensitive in this area. Just to give you an example, if I move away from that cardioid area around the front, and there's a camera on the side and around the back, you'll notice that it starts to change how it sounds and it's really just picking up reflections now because it's not taking up any of the sound really from the back. But as I come back around into the cardioid area around the front, you'll hear my dialogue comes back, and that's the cardioid shape at the front. There's other types of cardioid pickup pattern, such as this microphone, the Sennheiser MKH50, which is a super cardioid. What that means is it still has the heart shape around the front, but what makes it super cardioid is that it's got even more rejection from the rear. If I move around this microphone, you'll notice that I go off axis a lot quicker and I just sound a lot quieter from the rear of the microphone compared to the NT2A where at this point you could hear me still reasonably well. But as I come back on, I've become a lot clearer and it's a lot more accurate in where I'm stood in that cardioid pattern. Another common type of microphone pickup pattern is a figure of eight or bi-directional. This means that it picks up on axis sound from both the front and the back of the microphone, but rejects sound from the side. If you literally imagine a figure of eight where in the middle is the middle of the eight. If I just walk around now to show that on axis and off axis areas, you'll be able to hear a change in my voice. We're on axis there in the eight. As I come around the side, you'll start to notice a rejection, and that's because we're not in the pickup pattern, but as I come around the back, you'll hear the sound again like you did at the front, and that's because we're back in axis. Then if we come back around, you'll notice it dips out, and we're on axis, and then to the other side, it again rejects from the side. That's the figure of eight pickup pattern. An example of an omni-directional microphone it be something like this Sanken COS-11D Lavalier microphone. What it means by being omni-directional is it'll pick up sound from all around the microphone in any direction. If you imagine it's in the middle of a big sphere. If I just move this at different angles, you'll notice a slight change in my dialogue, but not really too much. It'll sound similar no matter where this microphone is, and that's because it's in that sphere. These are really good for recording things like choirs or, for example, a set of string instruments that are together. You can pick up sound from all around the microphone and not worrying about if you've been on or off-axis. A common pickup pattern that's used in sound effects gathering or dialogue outside is a shotgun microphone. These microphones are a bit different from the others. As the name suggests, shotgun, it directly points that sound and focuses in on one particular sound and has a good level of rejection from the rear and from the back. If I move away from the microphone here, you'll notice a decrease in the quality of my sound, but it's still going to be clear, is still going to pick up decent clarity from my voice. Even if I went back five, six, seven meters, it's still going to sound really good. Even if I just move slightly off axis here, you'll notice a big difference of what's being recorded. Same if I go back on through the axis onto the other side, you'll notice a rejection, as well. If I just have a little walk around the microphone, you'll be able to hear the different bits. It does have some pickup from the sides, as you can hear that from the capsule and, again, as we go back to the rear, it will pick up some of the reflections from the rear. But it really is about focusing in on one particular sound from a distance away. Hopefully by listening to those examples, you've now got a good understanding of why it's important to consider the pickup pattern of that microphone before choosing one to use. In the next session, we're going to discuss frequency response and you'll learn a little bit about why it's important to understand the frequency response of a microphone and how to decode that information when you see it. 5. Frequency Response: In this session, we're going to be talking about frequency response, what to look for and how to read a frequency response chart. If you've ever bought a microphone and looked at the technical specification of a microphone, you probably know it's the chart that shows the frequencies of that microphone. This is called the frequency response chart, and it looks a little bit like an EQ graph. The squiggly lines on this chart shows how sensitive the microphone is or isn't to certain frequencies. A microphone that's designed for singing will have slight boosts in the mid-range, where vocals sit, but a microphone that's designed for a kick drum will have boosts in the birth region. So it's good to see those two charts side-by-side. In particular on those charts, if we look at the frequencies along the bottom, on the kick drum mic, it favors the frequencies from 30 hertz to about 1,000, 2,000 hertz. If we compare the frequencies at the bottom of the chart for the singing microphone, the SM58, you'll notice that those frequencies are actually rolled off, so it's designed to get rid of some of that lower energy. Now let us listen to those instruments, so first we'll listen to a kick drum and then we'll listen to some vocals. If you look at the frequency EQ graph, you can see the frequencies which that instrument operates around, and then if you compare that to the frequency response chart for the microphone that's designed to record that instrument, you'll see that they both match. The manufacturers create these charts when a microphone is tested in a specifically designed acoustically dead studio. In these rooms there are no reflections, which means the graph shows the microphone performing in perfect conditions. By looking at this information and recognizing where those boosts in the frequencies are, we can work out if that's going to be the right microphone for us to be using. The standard human hearing range goes from 20 hertz to 20 kilohertz. So any frequencies that are shown outside of that frequency range won't be audible to the human hear. However, there's some frequencies outside of that range, such as some frequencies that can be felt. When looking at the frequency response chart, we can see that the horizontal numbers in the chart indicate the frequencies and the vertical numbers represent relative output in decibels. Before you jump into a studio session or a live application, it's worth really thinking about what you're going to be using that microphone specifically for and then choosing a microphone that favors the frequencies of the signal that you are going to be putting into that, like we said, a human voice, you'd want boost in the mid-range and a kick drum in the lower region. Next up we're going to be looking at cables and connectors of microphones. It might sound simple, but after you've invested in a microphone, is it okay to use cheap cabling? What kind of connectors do we need to be looking for in the microphones we're buying. 6. Cables and Connectors: When we're looking at cables, there's two components to them. There is the cable itself, and then there's the connectors on each end. Cables and connectors are often overlooked when purchasing microphones, but it is important what you use. Most professional microphones use an XLR lead with a male connector on one side and a female connector on the other. In a professional setting, you should never really use a microphone that doesn't have an XLR connector. Some cheap microphones might use jack connectors such as a quarter-inch jack or an eighth-inch jack, but I'd highly recommend avoiding these as they tend to give inferior results to XLR connections. I want to stress the point that from my experience, it is best spending a little bit more money on a quality XLR cable. Cheaper cables can let in quite a lot of external noise as the isolation inside them isn't as good as the more expensive ones. Also, the quiet prints a brick in, especially the connectors is the components that make up the connectors and cables and quiet as good. In my professional career, I only use cables with Neutrik connectors on them. The components in them are really good quality, they're less prone to breaking, and you can also fix them easier than other cables if they do break. I'd also recommend only using Van Damme cabling as again, the build quality is robust and the technical specifications of their cable is outstanding. In the next session, we're going to look at how to control two of the main issues when recording dialogue into a microphone, and that's plosive sounds and wind. 7. Plosive and Wind Protection: When recording dialogue inside or outside, it's really important that we have a couple of extra accessories in our kit to prevent issues from two of the main things that can cause bad audio, which is wind and plosive sounds. Pops and plosives naturally occur when we're speaking in our dialogue. The certain letters in the alphabet that carry more energy than others such as popping, bag, kit, test, it's a little example. If you'd say those words and put your hand in front of your mouth, you'll notice that on certain letters, you can feel the air hitting your hand. I'll give you a minute to try that out. When you say those words, you can feel some air being pushed against your hand. That's the sound wave energy that's being projected from your mouth toward your hand. What would you use here to stop the sounds getting into the microphone is we'd have a barrier in front of the source, which is your mouth and the microphone, and that's what we call a pop shield. Pop shields are normally made from a fabric or a metal mesh and it sits in front of the microphone and clamps to the microphone mount or an external stand and creates a barrier to capture all the extra energy coming from your mouth to the microphone. Pop shields are really inexpensive, you can even make them home from things like tights and a [inaudible] hanger, but they really added a good level of professionalism to your recording. It is worth noting there that some microphones do have inbuilt pop shields such as live microphones like the Shure SM58. It's got an inbuilt pop shields so you wouldn't need to add one and if you are using that microphone. Let's do a little example of what it sounds like using the pop shield and not using a pop shield. We're going to do a little test with them without a pop shield. I'm talking into the road and [inaudible] and hurtfully because it's got the pop shield there. A lot of that popping sound is eliminated so we'll just remove that. Now, when I'm talking into the pop shield, you're probably picking up a lot of that popping sound and it's not going to sound very great because it's going to be popping them, picking, popping, poppings up as in of popping. When we're recording outside, another main issue we're going to come across is the noise from the wind. Wind naturally carries a lot of best frequency energy, as well as sharing some of the mid-frequencies with the human voice as well. It's really difficult to get rid of wind sounds in post-production so it's important that we try and to eliminate that at source, and we do that by using a wind protection system. The most common type of microphone that we'd use outside is a shotgun microphone. That's often what you see in film and TV. You'll always see the shotgun microphone outside encased in a windshield. This just stops the wind from actually getting to the condenser of the microphone, but still it's all the frequencies come in that we want such as the dialogue. Because we're filming outside, we've got wind protection there. We're filming in quite a busy location but the windshield stopping all of that wind noise coming in and ruining the tech. In the next part of the course, we're going to look at a few applications of way you'd want to use a microphone, we'll look at a podcast with two people, a vice server, and recording a guitar. Using the knowledge we've learned in this course, we'll decide what microphone would be best to use in those applications. 8. How to Choose a Microphone (with examples) : By combining everything we've learned in this course, we should be able to have a scenario and then choose a microphone that's going to be suitable for it. So when we're choosing a microphone for a situation, we need to ask two questions first. Where are we going to be using the microphone and what are we going to be used in the microphone for? Once we've got the answers to those questions, we can start thinking about other features of the microphone. We need to consider the type of microphone, polar pick up pattern, the frequency response, the cables and connectors, and do we need plosive or wind control. So using all that information, we'll go through a few examples now so we can choose microphones for these situations. So first we'll think about what kind of microphone would we need for a voice over? So first, we need to ask the two questions; where are we going to be using the microphone? And that'll be in the home or studio, somewhere quiet. The second question is, what is it going to be used for? And that's recording my voice. So with that information is going to use for recording my voice, in a quiet home or studio, we can then think about the other elements of that microphone. So what type of microphone is it going to be? Well, we'd like a condenser because we want the best quality and we're going to be using it in a quiet setting. What pick-up pattern are we going to need? We're going to want to use a cardioid pickup pattern because we want to pick up my voice only, just in front of the microphone. What frequency response do we want? Well, we want something aimed at the vocal range, so the mid-frequencies. What cables and connections? Well, we're going to want a good quality microphone. So that's going to be XLR, and thinking about plosive and wind control, well we're definitely going to need something to stop the plosives coming from my mouth into the microphone. So we're going to need a pop shield. So with all that information together, I've picked the perfect microphone for this application, which would be a RODE NT2A. So the microphone we've chosen for a voice over is the RODE NT2A studio large diaphragm condenser with the pop shield. It gives a really nice warmth and creamy sound to your dialogue, which is great for doing them voice overs with. So next up, we've got a guitar amplifier on a stage as part of a live band. What microphone can we use to record the sound coming from the guitar amplifier? So we start with a two question, where is it going to be used? It is going to be used in a really loud environment on a stage, in a theater; and what is it going to be used for? It is going to be used for capturing the sound of a guitar, coming from an amplifier. Then from them questions, we can consider the other things. So what type of microphone do we need? Well, we need a dynamic microphone this time because it's in a loud environment. We're going to use a cardio pick up pattern because we can put that right in front of the guitar amplifier and just capture sound common stretched from the front. What frequency response do we need? Well, we can look at, sort of a mid range somewhere that it's going to pick up a lot of the different elements of the electric guitar and the sound coming from the amplifier. What cables and connections? It is going to be an XLR cable because we want the best sound that we can. Finally, do we need wind or plosive control? Well, we're not recording outside, so we don't need wind control and we're not recording dialogue. So we don't really need plosive control. So no, we don't. With all that information together, we've decided the best microphone to use for recording the guitar through an amplifier would be a Shure SM57. Here's an example. In the next scenario, we want to record a podcast with two people in the same room. So we go to the first two questions, where are we using the microphone? We will use it in the home, an office or studio, and the second question, what are we using it for? A podcast with two people speaking. So it needs to record two pieces of dialogue at the same time. So now we can consider the different elements of the microphone. So what type of microphone? We will want a condenser because we want the best quality sound. We want that crystal clear sound from that dialogue. Then we will decide on the pickup pattern. This one's interesting. If we had two microphones, we would do them as cardioid because we'd want one each just picking up their dialogue at the front of the microphone. But the interesting thing here is that we can actually use a figure of eight microphone, and that can be in the middle of the two people speaking on each side of it and both pick up, the sides, while rejecting sounds from each side. Then we'll look at the frequency response, which we want a mid-range because it's going to be vocals. The connections and cable, we want an XLR cable. Do we need plosive or wind control? It's not outside so no wind control, it's inside with people speaking to the microphone, so we're going to need a pop shield. So the microphone I'd use here would be a RODE NT2A in the figure of eight pattern. Thank you for joining me on the podcast. That's okay. If you could only eat one meal for the rest of your life, what would it be? That's a very hard question. I think it would probably have to be quite cliche and maybe go for a nice pizza. The final scenario we'll talk about will be somebody recording some dialogue for film or TV next to a main busy road. We need to ask the first two questions, where are we recording? So this time it's going to be outside, and what is the microphone used far? Well, it's going to be recording someone speaking. Next, we can look at the type of microphone. We're going to want a condenser because we want that quality crystal-clear audio from the voice, and we'll look at what pick up pattern we need. This time we're going to go with a shotgun pickup pattern because it's next to a busy road. We're going to want to reject a lot of that sound coming from the sides, which is going to be the traffic noise, and we really want it to focus in on the dialogue that's being said. The frequency response is going to be end at the vocal range. So the mid-frequencies, we're going to use an XLR cable and we're also because we're filming outside, going to need wind control. So the microphone I've chose for that situation would be a SENNHEISER MKH 416 with a windshield. So this is a SENNHEISER 416, we're using this in a really loud location, there is a main road with some pretty loud cars. As you can probably hear, you can hear some of that external noise, but it's mainly directional and picking up just my voice, which is really what we want in a noisy location. 9. The Project: You should now understand all the key elements to choosing the right microphone for the right application. For this project, I'd like you to pick a microphone for something that you'd like to record. It could be a voice-over, acoustic guitar, piano, singing, anything you like, and share that recording of what you've done, and maybe just explain what microphone you chose and why.