microphones

Microphones: Best Choices for Live Presentation or Video Webcast

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The staggering array of microphones available today can be overwhelming to someone who is not an audio expert. However, understanding a few basic principles of microphone design and application can make picking the right one for your situation pretty easy.

All microphones either pick up sound from all directions (omnidirectional) or have a specific directional pickup pattern. The main directional patterns for microphones are cardioid, hypercardioid (sometimes called supercardioid), or figure 8, each of these describing the shape of the pickup pattern.

The Presentation Microphones

For a presentation situation where the sound will be amplified through speakers, an omnidirectional microphone is generally not useful, because it will pick up too much sound coming from the speakers which will cause feedback.Feedback is that annoying ‘howling’ sound that gets out of control when an amplified microphone signal is ‘fed back’ into itself causing the system to go into oscillation. The one exception to this is an ‘earset’ or ‘headset’ type of microphone positioned very close to the speaker’s mouth. Because of the close proximity, the microphone will pick up the presenter much louder than the other ambient sounds.

An “omni” mic is a good choice in this application because the frequency response tends to be much flatter than a cardioid, so it sounds smoother. This kind of mic is less susceptible to loud “pops” coming from plosives (“P” and “B” consonants). It is also  less sensitive to slight position changes because its frequency response is the same in all directions.

The different basic ‘styles ‘ of microphones most commonly used for live presentations are: Hand-held cardioid microphones (ex. Shure SM58); gooseneck cardioid or hypercardioid lectern microphones  (ex. Shure MX418); ‘lavalier’ or lapel mics, which can be omni or cardioid (ex: Shure SM93 –omni, or Shure WL185 Cardioid); and headset or earset microphones which are usually omnidirectional, but some cardioids are now available (ex Shure MX153).

Here are some quick pointers about the different types:

Handheld Cardioid (or hypercardioid) microphone:  

Plusses:

    1. When used properly, these will give you the most gain before feedback. In other words, you can get them much louder than most of the other options even when in proximity to loudspeakers.
    2. The presenter can walk around and not have to be too concerned with their proximity to speakers. The mic can be placed on a stand, table stand or podium stand, and the presenter can remove it from the stand if he wishes to walk around.

Minuses:

  • Occupies the presenter’s hand.
  • The presenter needs to have good ‘mic technique’ – if he starts waving the mic around or not keeping it pointed the right way and near his mouth, there will be wild variations in sound levels and quality.
  • The mic has an obtrusive profile on camera, especially if it is positioned directly in front of presenter’s face.

Gooseneck Podium Microphone:

Plusses:

    1. Less obtrusive on video
    2. Positioning is usually easy

Minuses:

    1. Presenter cannot move away from podium or turn his head while speaking, or there will be severe level drops.
    2. Microphone may pick up noises from podium unless it is properly shock-mounted
    3. These microphones tend to be very sensitive to plosives, especially if the presenter tends to get too close to mic. Always use a foam windscreen, and direct presenter to stay 3-6” away from microphone when speaking.
    4. Temptation for presenter to move microphone into different position while presenting which will make a large and annoying noise.

‘Earset’ or ‘Headset’ Microphone

(note: ‘earset’ microphones usually refer to a microphone that goes over one ear, while ‘headset’ microphones loop over both ears with a metal wire that goes around the back of the head. The headset configuration tends to be more stable, but can often be a problem with female presenters because it can affect their hair):

Plusses:

    1. Presenter can walk around hands-free
    2. Position of mic relative to the presenter’s mouth does not change when moving his head, so sound quality stays very consistent
    3. Good gain before feedback due to close proximity of microphone to the presenter’s mouth
    4. Fairly low profile for video. These mics can be purchased in different color shades to match the presenter’s skin color which can make them even less visible on video.
    5. Little plosive sensitivity due to omnidirectional pickup pattern.

Minuses:

  1. Can be tricky getting the positioning right, especially if the presenter has an odd size ear or an unusually shaped face.
  2. If these mics are re-adjusted frequently for different presenters, they often break from being bent and re-bent.
  3. Some presenters find the headset annoying or distracting.

Lapel or ‘Lavalier’ microphones:

Pluses:

    1. Very low profile and unobtrusive on video. These can often be positioned in such a way that they are practically invisible.
    2. The presenter can move around hands-free.
    3. Plosives are generally not a problem because the microphone is fairly far from presenter’s mouth.
    4. If the microphone is placed in a central position, sound only changes slightly when the presenter turns their head.

Minuses:

  1. Very difficult to get a lot of volume due to the distance from the presenter’s mouth. Feedback can be a big problem: the presenter cannot go out into the audience or anywhere close to the speakers.
  2. Although a cardioid lavalier can produce a little more gain before feedback, it presents other problems, such as greatly increased sensitivity to clothing noise, head turns, and plosives.
  3. Presenter inadvertently touching or bumping mic with hand, producing a very loud noise (for example, a presenter pats his chest, forgetting there is a mic there or adjusts tie).

 

The “right” microphone is different for each application. Do you have questions about which mic is right for you? Get in touch with the community below!


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