Simply stated, a microphone changes sound waves into an electronic signal which is transmitted to an amplifier and then to speakers or perhaps a tape recorder. For the purpose of most singers, the type of microphone most commonly used will be a cardioid type, which has a narrow pattern of audio sensitivity. This unidirectional pattern will pick up sound from a source directly in front of it, but will tend to avoid sounds from other directions. This is helpful in preventing bleed-in to the mix from unwanted sounds or in the attempt to control feedback, etc. In those cases where you want to amplify sound from all directions an omidriectional mic is used. Besides these basic pattern characteristics, different manufacturers design specific characteristics and sensitivities into various mics for different purposes, such as amplifying musical instruments. Choosing the right mic is important to the nature of the desired results.
There are three basic pickup patterns used by most microphones:
Omnidirectional - Sensitive to sounds from all directions. Unidirectional - Sensitive only in one direction, usually a cone shaped pattern. Cardioid - A type of unidirectional mic, sensitive in one direction. It picks up sound in a heart-shaped pattern, strongly from front, and about half as loud from the sides.
Test your microphone
What type of mic do you have? Speak into the mic head from the front and then from the side. If the sound is fairly even from all sides, you have an omnidirectional mic. If your voice fades when you speak from the side, you have a unidirectional mic. Mics are sometimes selected on the basis of how they generate the initial audio signal. Condenser type mics require an additional power source to operate — either with a battery or phantom power supplied through the cable from the sound board. They tend to be brighter, crisper and require less amplification. In contrast, a “dynamic” mic uses only the sound source to generate signals to be sent to the sound board. Wireless mics use a tiny transmitter to send audio to a receiver connected to a sound board. A limited variety of mic types are available for handheld or lavaliere use. These mics are great but are not without their drawbacks. They run on batteries (always use alkaline) which have to be changed regularly, are sometimes subject to transmitter interference or “dropout” (a lapse in the received signal), and do not offer the variety of types and qualities available to hardwired. A hard-wired mic is the standard type of mic which has a cable wired directly into a sound control board. Most mics used today are of a low impedance type (low resistance) which are resistant to interference and allow longer cable runs. A lavaliere (or lapel) mic is tiny, hardly noticed mic clipped on a person’s clothing, great for amplifying speech, but not so good for the broad dynamic range of singing. Some people love these because they leave the hands free and no cords to dangle — others hate them because the sound is not as good as a larger, hand-held mic and there is no dynamic control over the volume (by lowering and raising the mic). As in many other things, with mics you get what you pay for. The better quality instruments are not cheap and they must be used together with good quality equipment and acoustics to produce the desired results.
Using a Mic for maximum performance
When used for vocal amplification, a microphone should be mounted or held within a tolerance of between 3 and 8 inches of the person. To keep a mic within these tolerances, a gooseneck or boom can be used on a stand or lectern to adjust the vertical/horizontal placement. When holding a microphone during singing , it’s best to hold your mic approximately 3 to 4 inches under your chin. If you hold the microphone father away, the sound operator must increase amplification, and unfortunately, when excessive volume must be used to amplify your voice, it may also amplify other surrounding sounds. This makes it difficult to “mix” or separate your voice from other nearby sounds or singers which may “bleed” into your microphone. Do not speak directly into the mic, but “across” the mic, in order to avoid pop caused from your breath. Another problem in obtaining good mic mixes in services is separating the volume of the drums. Drums (acoustic type) often project so loudly (mostly the cymbals) that they can be heard through other microphones on the platform. You can turn down the microphones (if any) used to amplify the drums, but depending on the acoustics and type of mics used, their sound may be still heard through the other mics of the singers. Consequently, the sound of the drums cannot be easily separated from the other sounds of singers or musicians. (When such problems exist, a drummer must reduce his playing volume or a clear acoustic shield must be placed around the drums.) Whenever other acoustic instruments are used, it is very important for all singers to hold their microphone close to their mouth so that “their voice” is what is heard through their mic, not all the surrounding sounds. Even other singers can “bleed” into your microphone, making it impossible to mix the individual voices. How important it is to hold your mic properly. Holding a mic too close can also be a problem. This can create “distortion,” which makes your voice sound fuzzy and indistinguishable. Avoid a “rubber arm.” Practice holding your mic at an acceptable distance and learn to hold your arm at a consistent arc which will keep your mic at the right position. If your mic distance fluctuates much, so will your volume, causing difficulty for the sound operator to maintain a good mix. During moments that a microphone is not being used, it should never be held randomly in any direction. If the mic is still “live” and not used, it should always be held in an upright position, lowered from your mouth if so desired until you need to use it again. Due to the concern in delivering sufficient power to the monitors for the singers to hear themselves, the “feedback” threshold is often stretched to its limits. By inadvertently pointing the mic toward or near a speaker may create shrill feedback. There is another problem which is caused by holding two or microphones too close together. This is called “phase shifting,” and creates unpleasant, unnatural sounds. It is advisable to never allow two live mics to come closer than two feet from each other.
What not to do with a Mic
1. Don’t blow into a mike to see if it’s on. This sound is annoying and you might blow harmful moisture (spit!) into it. It’s a better idea to say something or tap it lightly with your finger.
2. Do not speak directly into a mic. You’ll usually create a popping sound, especially if you make a “P” or “T” sound. A wind screen on the mic will help to reduce this, but it’s best to improve technique by speaking across the mic rather than into it.
3. Do not place a clip-on mic under clothing. Although out of sight, the mic will pick up rustling noises as clothing rubs against it, and it will muffle sounds. It is better to clip it on a lapel or wear it around your neck. For stage or TV productions, lavaliere mics can be concealed under clothing if first placed into a silk pouch which reduces noise-causing friction.
4. Do not wear or handle a mic when you step into a baptistry. A hard-wired mic may deliver a serious electrical shock to a person grounded in a pool of water. This danger doesn’t exist with a wireless mic, however water and moisture is an enemy to any electronic device and may ruin your equipment. It’s better to mount a mic above your head or in front of baptistry. In those “unique” circumstances when nothing else can be arranged, a hand-held wireless mic, sealed inside a zip-lock plastic bag can be used. The plastic will waterproof the mic, but sound (somewhat muffled) will still pass through.
5. Don’t abuse your microphone. Don’t drop it, subject it to shock, or hold it dangling by the cable, etc. It is a delicate instrument and may be expensive to repair or replace. Store it in a clean, dry place when not in use.