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Microphone Placement is Everything!

February 17th, 2016

woman public speakingToday I’d like share about best practices for where to place a fixed microphone when using one for speaking. These best practices apply to everyone including sports announcers for the Big Ten Conference, presidential candidates from a lectern, and also general handheld applications.

The speaking voice is a source, and like your radio or music player, it creates sound and it projects its sound to the listener. To increase the quality of your voice for listeners, you need to apply a sound system, i.e speakers and microphones. When using these pieces of equipment, a speaker must consider placement, which I will cover for you here.

The top considerations are: the placement of the microphone, the placement of the speakers and the location of the hard surfaces in the room.

Respect the room. This is the most commonly overlooked aspect. Before you ever step up to the microphone or sit behind one, take an inventory of the room including furniture, walls, and floors, especially around where you will be speaking. The room set-up can be your friend or it can be your worst enemy.

Here are a few observation to note:

• Is the room full of hard surfaces?
• How close is the lectern to a wall?
• Is the table I am speaking from have a table cloth on it?
• Are the audio speakers located behind me or in front of me?
• How close will the next microphone, or another sound source, be next to me?

3to1 RulePlacement is everything. If you want to prevent headaches and fighting with the sound guy then work with the room set-up folks and follow the 3:1 Rule as a “rule of thumb” – a broadly accurate guide or principle, based on experience or practice rather than theory. I believe in real life examples for the best results which is what experience has taught me.

The 3:1 Rule is a guideline to help you set up your equipment so they prevent audio issues from their origin. The sound that you make with your mouth is like a speaker and it will broadcast where ever you point it. So to provide a guide, the 3:1 Rule helps you in this way. If your mouth is 1′ away from the microphone, then keep all other sources at least 3x that distance away from your microphone. This would include other microphones, hard surfaces, music sources, rustling papers, clicking keyboards, fans, etc.

Audio Technician notes: Audio Input Gain. The 3:1 Rule will not work if the sound person does not understand sound structure. Here are the two that will make or break an event.

Unity Gain. Keep all the audio source gains and the mains out pretty much the same, not all over the place, looking like a zig zag on the mixer board or “riding the fader” on any other sources. The gain on your microphone should be close to the gain level on the rest of the other microphones, if there are any near you. The common problem is that if you are at a head table with other microphones, even using the 3:1 Rule, the sound person may turn up the gain to the other microphones which will start “elbowing in” into your area.

Phase Cancellation. In other words, when two microphones are in close proximity to one another and you wonder why you can’t get enough volume out of them, it’s because they are cancelling each other out. This is a result of the two identical signals, which if are 100% or 180 degrees out of phase, they will completely cancel one another if combined.

Boundary Microphone

 

 

Best Practices for a Head Table Set-up: Set the audio mixer to a Unity Gain structure, set the microphone up in a uniformed manner, all about the same distance from the edge of the table. If there is someone who is softer spoken than the other person, then move the microphone closer to them. I recommend a gooseneck microphone or a boundary or “plate” microphone.

 

 

 

Angled CrossfireBest Practices for podium miking with two microphones. Here the two mics are placed with their capsules as close together as possible and angled in a “crossfire.” This provides a wider overall acceptance angle, allows stereo miking with excellent mono compatibility, and largely avoids the phase-interference problem. Podium miking with two microphones has the two mics placed with their capsules as close together as possible and angled in a “crossfire.” Proper mixer set-up is to pan one microphone to the left  and the other to the right, which will avoid cancellation.

Speaker Placement: The main speakers must always be placed in front of the person speaking otherwise there will be feedback (loud screeching sound). The speaker cabinets should be in a location that will not be in the walking path of the presenter or easily walked in front of.

Speaker Placement

Acoustics Considerations: A common challenge also includes items in the room that conflict with the microphone’s performance.

Here are a few solutions: isolation stand

Consider the way the microphone is attached to the podium or on the table. Vibrations from the floor or the table top can be distracting, so I recommend isolating the microphone stand or mount. Placing a cloth on the table or podium is a great first step to reduce those unwanted reflections and vibrations that naturally occur. Microphone companies have what are termed “isolation stands” and they offer mounting hardware that is a more permanent solution as well.

Final Word: Speak directly into the microphone!

High frequencies are very directional, and if you turn your head away from the microphone, the sound captured by the microphone will get noticeably dull.

If you are interested in further information, I’ve found the following resources valuable:

The Three to One Rule and Phase Cancellation Fully Explained

Two Common Problems

Training People How to Use Microphones

Hope these recommendations help you to have a successful presentation!

Tony, the AV Guy

Tony, the AV Guy


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