What to Do About Microphone Pet Peeves
An Audio By Design reader named "Bro Duke," writes in about his microphone pet peeve, "their lack of internal filters. Specifically, to limit the popping of 'Ps.' On one occasion, I made a comment to our local Board Of Supes at city hall. Though my face was a full 12 inches away from the microphone, every time I uttered a 'P.' I could hear it pop loudly in the PA speakers."
What could be done to improve the situation here? Although the mic in question was not named, from the description, it seems to exhibit the proximity effect, where the lower frequencies are boosted more and more as the talker moves closer and closer to the mic. So those plosive sounds get over-emphasized.
We can assume from this information that this microphone has directional pickup characteristics, maybe cardioid or super-cardioid, since omnidirectional microphones aren't prone to the proximity effect.
So one solution could be changing the mic to an omni with similar sensitivity characteristics. But that may not be appropriate in this acoustic space. Municipal meeting rooms are often reverberant and noisy (noise from people attending the meetings and from such things as air handlers, for example). If that's the case here, then a directional mic could indeed be what is needed. But not all directional mics are constructed the same.
To obtain a directional polar pattern, sound needs to enter the space behind the diaphragm, in addition to impinging on the front, to create acoustic cancellations within the mic. The magnitude of the cancellations depends on the arrival angle of the sound source.
Typically, directional mics are made with a slot or a number of slots along the side of the mic. Mics with only one slot tend to have the greatest proximity effect. You may have to stand three feet from the mic before the low frequency response starts to flatten out and those "Ps" stop popping.
Perhaps the mic in question is of this construction. A solution would be to change it out for a mic with multiple slots along the side. These slots are usually tuned, with slots tuned to the higher frequency slots closer to the front (and the diaphragm), and the ones tuned to the lower frequency ones towards the rear. With this type of construction, proximity effect is reduced, and in some microphone designs, nearly eliminated, and you would be able to stand 12 inches or less from the mic without producing over-emphasized explosives.
Another way that mic manufacturers help out with the low frequency response is by providing a switchable bass roll-off filter in the mic. If the mic will be used at a distance where the proximity effect is evident, then switching in the filter to reduce the lower frequencies can often help. Some mics come with filters with a selection of cut-off frequencies.
We don't know if our mic in question has such a filter, but if it does, try switching it in. Also check if the mic mixer used in this system has an equalizer, or even a simple low cut filter, in the channel to reduce the level of the low frequencies.
Our fearless reader Bro Duke also observed more "P" popping on the local news on a TV station in a major market: "Their news anchor has been popping Ps intermittently for about a year now."
Could it be they are using a directional lavalier? Does it have a bass roll-off filter and is it switched in? Or can it be equalized at the audio mixer? Can the lav be positioned differently, maybe a little farther away from the newscaster's mouth?
Also, in this case, an omni lav might be the better choice. Most local newscasts originate from a studio and hopefully this particular studio has fairly good acoustics and low noise. And chances are there isn't a studio audience, so sound reinforcement (and obtaining enough gain before feedback), shouldn't be an issue.
This brings up the importance of having a variety of mics at your disposal to use as the situation requires. In addition to the different characteristics discussed previously, mics come in all price ranges, with quality to match.
Microphones need to stand up to some rough handling, especially those intended for handheld use, for fieldwork or for sound reinforcement. In general dynamic microphones tend to be more rugged than condensers, can operate over a wider range of temperatures and humidity, and they don't have to be powered. That's why they are often used in ENG applications.
But that's only part of the story. How the diaphragm element is mounted in the microphone housing and how the housing is constructed are a couple of factors that will determine how resistant the mic is to shock and vibration, handling and wind noise, and hum and buzz.
Better quality mics tend to incorporate such things as a shock mount for the diaphragm and the internal elements, a tough metal grill windscreen, a multilayered windscreen, a wind filter for side openings, a hum-bucking coil and a steel housing. In addition, accessories often include an external shock mount that screws onto a mic stand through which the microphone is placed, and an external wind screen.
Condenser mics have some advantages of their own. They typically have higher outputs due to their internal electronics, have a smoother and extended frequency response, and better transient response compared with dynamics. Look for a low-noise mic especially if you are trying to capture low level sounds, like for a nature program. But be aware that some condenser mics have been known to exhibit the pin-1 problem and also could not be used in high RF environments.
Modern lavalier mics tend to be condensers and the better ones are designed to minimize clothing, handling, and cable noise. Some are even resistant to perspiration, moisture, and salts.
In general, dynamic mics can respond to higher sound pressure levels without distorting compared with condensers, although there are some condensers designed specifically for high sound levels.
Condensers with their higher output levels can overload the mic input channel on a mixer. For that reason, condensers often are equipped with a switchable attenuator, with one or more attenuation settings.
It would be well worth the time to review microphone specifications and user guides, and to gain an understanding of the various characteristics of different mics and their applications. Try them out before you make your final decision and try to buy the best quality you can afford. And then have fun working and experimenting with them on your projects.
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