Video in Educational Research

Audio Technology

• Typesof Mikes
• WirelessMikes
• PZMMikes
• MikePlacement
• MikeConnectors
• MikeLevel vs. Line Level vs. High Level vs. Low Level
• Balancedvs UnBalanced Audio Lines

Typesof Mikes

• Types of mikes include:
• PZM Mikes
• Lapel or Lavalier Mikes
• Shotgun Mikes
• Handheld Mikes

 Typesof Wireless Mikes Types of Wireless Mikes include:

• Handheld Mikes
• Lavalier or Lapel Mikes
• Wireless transmitters could take an input from a PZM Mike

 Type of Microphones

The selection of the correct microphone while taping is the most important choicethat the eduacational videographer can make. Using the wrong microphone is the number one error made, as well.

 While professionalmikes for the broadcast market cost over a thousand dollars, very superior mikes are availablefor under $300. The difference between cheap mikes and these $300 middle-pricedmodels is analagous to the difference between using outdated black and white film andusing fresh new Kodak color film. One should remember that the better mikes produce sound that is sharper, chrisper and more vibrant. These mikes make it easier to hear what really happenend in the classroom. Further they come in all the types necessary to do the different jobs required.
 Take enough time to make the proper selection of microphones. Most likely this will include a PZMMike and a radio mike. In your budget,make sure that you have at least 15%-20% just for the sound (headphone andmikes). As you can see in our sample budgets the$5000 budget includes $1000 in the proper sound equipment.
Microphones types are divided in the way the mike picks up the sound (i.e. the pattern of thesound pickup), and the type of connection and cable it uses (e.g. balancedor unbalanced, wired or wireless ). You could also have the microphone work via a wireless transmitter receiver combination.
 In the picture above you can see the thetypes of microphones.
On the right are PZM mikes thesetypes of microphones (Pressure Zone Microphone) are especially appropriate for picking up the sound of a group discussion.The mikes are inexpensive (e.g. the Crown PZM, which has a mini connector for your camcorder is only $130).These Shure PZM mikes are in the $300 range.

 Mike placement makes a huge differencewith all microphones.

DetailedDescription of Specific Audio Connector Types

 Types of audioconnectors include:

• XLR Connectors, Male and Female
• 1/4" Phone Jack, Male
• RCA Jacks, Male
• Mini Stereo Jacks, Male

 Each type of connector is labeled in the linked picture above.

Levels

The Rules of Audio Inputs and Outputs:

• Connect Mike outputs to Mike Inputs
• Connect Line outputs to Line Inputs

The background knowledge is:

• High Level = Line Level
• Low Level = Mike Level

 When connecting audio equipment together one needs to be aware that besidesthe connector flavor, there are two main levels (or amounts -- really voltages)of audio inputs and outputs.
 Line Level outputs and inputs are common to all stereo equipment. The tapeinput into your receiver, the CD input into your receiver are all line levelinputs. Line level is an amplified signal, you can feed it down cables withlittle worry of interference from spurious RF due to the fact that the signalis so much hotter than the local RF.
Mike level inputs and outputs are common to all CamCorders. A microphoneproduces a low level of voltage change which goes down the wire. The inputamplifies that change and produces the resulting audio. Obviouslly RF signalshave a far better chance of interfering with this low level signal. Thusmicrophone cables for CamCorders should be short (unless one uses balancedmikes with cable with XLR connectors).
 

Balanced vs. UnBalanced Audio Lines

One remaining bit of audio knowledge is understanding the difference between

balanced lines

and

 unbalanced lines.

Balanced lines use three wires with the outside wire being a shield aroundthe inside two. The inside two wires are thus shielded from external RF.The common connectors for balanced audio is the XLR connector.
Unbalanced audio lines use just two wires, there is no shield. The signalpasses down the two wires unshielded from outside RF.
Home stereo connection cables are unbalanced line audio. The typical professionalquality microphones use balanced line audio.
 Balanced line connectors are XLR,
 unbalanced line connectors are common to CamCorders and to stereo equipmentas shown.

Consumer level CamCorders use unbalanced microphone inputs with stereo minijacks, but they often have separate line level inputs via RCA jack connectors.
 

 and labeled in this picture.