THE DIRECTIONAL PATTERN OF MICROPHONES
Microphones are characterised by very different properties. Aside from how a microphone works, the directivity is probably the most important characteristic.
The directional pattern of a microphone is essential information and has a major influence on the subsequent recording result. There are several different directional patterns, such as omnidirectional, figure-of-eight, cardioid or lobar, which you may encounter when researching or buying a microphone may encounter. We will explain what directional patterns mean, what is important and what types there are.
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What is meant by directional characteristic?
The directional pattern indicates from which direction and how strongly or sensitively a microphone picks up sound waves. Depending on what directional pattern a microphone has, it will be more sensitive to sound from certain directions than other microphones. Microphones are therefore not so different from human hearing in this respect – we also have different ways of hearing and picking up information: Sound from the front is received louder than sound from the back (shadowing effects due to the auricle).
What do directional patterns reveal?
The spatial recording field of a microphone can be visualised in a plane on a polar diagram (see Figure 1). This diagram is circular and describes the direction-dependent volume. 0° is the main pick-up direction of the microphone. One line corresponds to a certain frequency that is to be specified. The closer the line is to the centre of the circle at a certain angle, the quieter the microphone signal is at that angle relative to 0°.
A directional characteristic is also always frequency-dependent, which is why several frequencies are often displayed (i.e. several lines). Although the polar diagram shows the respective pattern in two dimensions, this does not correspond to reality. A microphone picks up sound in space – i.e. all around and in three dimensions. The polar pattern on the polar diagram depends on how a microphone picks up sound waves in the room.
What directional patterns are available?
There are different types of directional patterns a microphone can have. The names are derived from the different-looking polar diagrams, which visualise the recording volume in relation to the angular dependence.
The basic directional patterns are
Other mixed forms also include:
All directional patterns at a glance:
The basic patterns in detail
Omnidirectional pattern
Microphones with this directional pattern pick up sound waves equally from all directions, i.e. omnidirectionally. For this reason, the corresponding polar diagram shows a circle. These microphones are particularly suitable for recording several people standing around the microphone at the same time. As a result, they are often used for film, video or editorial radio projects. However, because microphones record everything around them, they are more susceptible to feedback and tend to be unsuitable for very loud and noisy environments.
Figure-of-eight pattern
In this case, the microphone picks up a lot of sound from the front and from behind. Laterally, on the other hand, it records almost no sound waves – the main cancellation is therefore at 90° or 270°. The figure-of-eight pattern is mainly found in ribbon microphones, which is mainly due to their special design. The advantage of this is that lateral noise is greatly reduced.
The figure-of-eight pattern of the M 130 dual ribbon microphone results in a consistent sound. The microphone is also extremely insensitive to lateral pick-up and only picks up low levels.
A portrait of the mixing characteristics
In addition to the directional characteristics mentioned above, there are also mixed forms that are very frequently used in microphones.
Cardioid pattern
The classic cardioid can be understood as a cross between a sphere and a figure-of-eight. Cardioid microphones primarily pick up sound from the front and block out sounds from behind – i.e. from 180°. Lateral sound waves are recorded with increasing attenuation from front to back. The key advantage of this directional pattern is that these microphones are less susceptible to feedback than an omnidirectional microphone, for example, but still forgive a less precise alignment to the sound source due to the wide recording angle at the front.
Intended use:
These microphones are often used on stage, in the studio or for interviews, such as our FOX USB studio microphone. The FOX’s cardioid-pattern large-diaphragm condenser capsule guarantees accurate sound conversion and low inherent noise. Cardioid-pattern microphones are often the first choice for recording speech in particular.
Our M 70 PRO X also has a cardioid-pattern pick-up pattern. When handling the M 70 PRO X, a direct pick-up or recording source is important, which has the advantage that keyboard noises, room reverberation or other noise sources are hardly noticeable. So, if you are looking for the typically powerful “broadcast sound”, you should opt for this dynamic microphone.
Wide cardioid pattern
Microphones with a wide cardioid pattern are somewhere between omnidirectional and cardioid. As with the cardioid, the maximum cancellation is also found at an angle of 180°, but this is less pronounced with the wide cardioid.
Hypercardioid pattern
This directional pattern is very similar to the figure of eight on the polar diagram. The difference, however, is that sound from the rear is picked up less sensitively, while the front pick-up width is somewhat larger. The angle of maximum cancellation is 115° and 245°.
Intended use: Our TG V70 (s) is a vocal microphone with a hypercardioid pattern. The dynamic microphone impresses with its excellent resistance to feedback – both in front of the stage and behind the mixing desk.
Supercardioid pattern
This directional pattern is very similar to the hypercardioid on the polar diagram. The difference, however, is that sound from behind is suppressed a little more. The angle of maximum cancellation is 125° and 235°.
Intended use: The TG D35 drum microphone from our Touring Gear series is a good example of this. The supercardioid pattern enables high channel separation and thus ensures a clear sound.
Lobar pattern
The lobar pattern is the most focussing directivity. The characteristic side lobes can often be recognised in the polar diagram. With a lobar pattern, the sound arriving from the front is recorded almost exclusively. This is also the main advantage, because by fading out the side and rear sound and the resulting narrow directivity, lobar microphones are the least susceptible to feedback. However, these microphones should always be very well aligned with the sound source that is to be recorded, as even small angular deviations can result in a large loss of level and a noticeable change in sound.
Directional pattern and proximity effect
The distance at which a microphone is used plays a major role. This is therefore something that must be taken into account at the development stage. The intended use is therefore a crucial factor when choosing the right microphone. The directionality of a microphone determines the intensity of the proximity effect.
