Lavalier Microphone (Viers, 2012, 13, 25, 67-83)
The Lavalier microphone is one that connects directly onto the talent. They are good for noisy locations as they are usually an Omni-directional microphone pointing upwards towards the talent mouth. They can also be used as a boundary microphone when planted on the talents chest acting as a sound board, so it can also pick up dialogue from other sources. Great for when Booming or Boundary microphones can’t be used as the frame of the shot may be too wide to fit in.
However, there are many draw backs from using a LAV microphone:
>Acoustic Shadow: The acoustic shadow is when sound waves from a sound source don’t directly reach the microphone, making the sound dull and flatter. Objects blocking sound waves reduces the higher frequency pick up from the microphone creating this effect.
>If the talent is moving their head around whilst acting out a scene, the recording level would fluctuate as the sound source (their mouth) would be moving to and from the microphone.
>If the talent leans over hard surfaces, it can create harsh echoes and slaps picking up unnatural reverb. To reduce this from happening, place an acoustic sheet or carpet over the surface. However, you can only do this if the surface is out of shot.
Hiding LAV Microphones
Hiding LAV mics is also an issue you will face. Clothes absorb higher frequencies so mic placement is key. It also loses sibilance which is at the range of 6KHz- 10KHz. You can buy microphones with have an increased sibilance pick up to reduce this problem
Always try and place the microphone at the center of the chest. If the talent is talking to someone on their right, place it more to the right, the opposite if the talent is speaking for someone on their left. Choose what placement works best for the scene. Find out where the talent will be facing when delivering lines in a scene. This will allow you to determine which placement is best.
Contact noise
This is when clothing is in contact with the microphones creating noise that will cloud over your dialogue. You can prevent this by:
>Using a static guard.
>Ask the costume departments to use guards.
>Rubber alternatives to jewelry.
>Check microphones regularly to make sure they are still in place and aren’t rubbing on any clothing.
Underneath is a link that shows techniques of hiding you LAV microphones and reduce noise.
https://www.youtube.com/watch?v=D85HmR825wM&spfreload=10
3:1 Rule
Many microphones on set can cause phase cancelation. Phase cancellation is when noise from microphones dip in and out as a result of interrupting each other’s waveforms. This makes the recordings sound hollow.
The 3:1 rule is when you turn off inactive microphones when in close proximity to active microphones and then turn up the active microphones to get rid of any phase cancellation.