If you’re involved in video production, or you’re a musician looking into recording, there are some basics that you should know about recording equipment. Today, we’re taking a look at microphones.
In the world of professional audio, there are several major polar patterns that can be utilized when constructing a microphone. These include cardioid, omnidirectional, and figure-8 patterns (these are at least the standard ones). Each of these patterns has a different purpose and works for a different situation. Every experienced audio engineer will need to have at least one of these polar-patterns in their toolbox, for this very reason. Here is some beginning information about microphone polar patterns…
Omnidirectional microphones have a wide pickup pattern that is great for recording group sounds, such as the noises in a room, or a choir singing. Compared to other types of microphones, a decent omnidirectional microphone will have a minimal amount of noise and will capture an even range of frequencies, regardless of how close or far the subject is to the microphone. Also, no portion of the microphone’s pickup pattern will vary in frequency, which can be a problem with cardioid microphones.
However, this doesn’t bode so well when you need to record an isolated sound, or need to prevent stray noises from getting into your recording. Omnidirectional microphones will pick up spill sound from everything in its vicinity. This can make it tricky to record musicians that need different microphones to capture the richness of sound from each instrument, since the omnidirectional mic won’t be able to isolate anything.
Figure-8 microphones have a pickup pattern that picks up sound on both front and back of the microphone, but nothing off to the sides. This makes it exceptionally great for different types of music recording, since you can record duets on the same microphone with great results, but only if you have the two singers singing towards each other. This can be essential for stereo-mixed recordings, if that is the situation. On top of that, figure-8 microphones can be great when recording interviews, since the interviewer and interviewee can be recorded with one simple solution, but without the spill noise from other noises.
For these situations, figure-8 microphones are incredibly useful. However, due to the specific peculiarities of the pickup pattern of figure-8 mics, this makes it probably the least used tool in an audio engineer’s toolbox. Although, if you wanted to completely cut out the audio that is being recorded from the sides, you could position the mic so that no sound will be recorded from the back of the microphone, thus making it highly directional. However, you can get a similar effect with specific types of cardioid microphones.
Cardioid microphones are like a mix of the other two main patterns. They have the strong front signal of a figure 8, with the side recording advantages of the omni mic, but without any pickups on the back. The advantage of cardioid microphones is actually quite simple. It will pick up wherever you point it, without picking up behind the microphone. Cardioid microphones are excellent at recording live bands, since they will pick up the entire stage, without picking up the sound of the audience. Cardioids are also great at picking up isolated sounds, which is what makes them so sought after. Specialized cardioid microphones, such as hypercardioid and supercardioid microphones, are also used by filmmakers to record sound on set.
Cardioid microphones are exceptionally useful, but also have a few disadvantages. For example, cardioid microphones suffer from off-axis coloration, which means that there is a sharp drop in the microphone’s ability to pick up high frequency sounds unless it is in the front of the pickup pattern. When arranging how a band performs on stage, this needs to be taken into consideration. However, higher end microphones will often be engineered to minimize this drawback. The other major issue with cardioid microphones is that they will experience much stronger bass frequencies if the source of sound is much closer to the microphone. For singers who like to sing too close to the microphone, this can be a problem.