This is my outline from a Professional Development session I had with about 150 elementary school music teachers in 2022 (Charlotte-Mecklenburg School System or CMS). I offer modified versions for middle and high schools.

There are PowerPoint slides to go with this outline here. The live version of the talk also includes demonstrations, engaging role playing and even a few dad jokes!

These are in no particular order. Can you guess which issue I think is most important?

1. Feedback (ringing) – In addition to the unpleasant sound it can also be a root cause of:
   1. Not hearing the choir over the track or piano
   2. Singers feeling like they have to shout-sing to be heard
   3. The audience being distracted b/c the sound system is drawing attention
2. Wireless mic problems – dropouts, ear mics sound like a phone, broken cables
3. Doing sound without the context of the main goal – Interference with the purpose of the event

If you answered #3 as the most important issue, you guessed correctly.

The Main Goal of the Sound Person

To support the emotion and story of the event. This will drive all artistic and technical decisions.

How?

• Give performers 100% of the attention – Don’t make the audience conscious of the sound system. Aim for:
  • Clear speaking
  • Clear lyrics
  • Clear melody
  • No feedback
  • Natural sounding
  • No missed cues

• Play appropriate music before and after to help set the atmosphere.
• If the audience is dancing to your song, you’ve got it. If they are plugging their ears, you’re not there yet.

Feedback Strategy Deep Dive

Feedback happens when the mic can hear the speakers.

There are many causes – Like fixing a roof with half a dozen leaks, you have to address all of them to solve the problem. Here’s a checklist of the things to work on.

• Mic selection
• Mic placement – Carefully considered mics in carefully considered places
• Mic usage
• Mic EQ
• Monitor Routing
• All speakers EQ’d to match the room

Mic placement and selection

Mic Selection

Mic Polar patterns

• Cardioid – Good rear and side rejection
• Hypercardioid – Best with tracks when angled down on the choir
• Shotgun – Super directional from the front but has rear sensitivity. Also large.
• Omni – No side or rear rejection
• Figure 8

Dynamic vs Condenser (built-in amp that needs power)

• Dynamic – Easier with PA – no power needed, least sensitive, great rear and side rejection, proximity (more bass when closer), not as sensitive to popping
• Condenser – Harder with PA – needs 48v or a battery, most sensitive, not great rear rejection, no proximity, very sensitive to blowing air

Mic Placement

• • Keep mics behind the main speakers.
  • Position loud instruments on the null (non-sensitive) side
  • Hanging mics or choir mics on stands
    • Beware of phase cancellation – Wherever mic pickup patterns overlap, dead spots and tonal anomalies are created. This is called phase cancellation and it can be total (no sound) or partial (unpredictable volume dips and funky equalization).
    • Follow the 3:1 rule. Mics should be no closer to each other than three times the distance to the sound source. So, for example, if the singers need to be picked up from five feet away, the closest the mics would be is 15 feet apart. Use a tape measure. If hanging mics are too close together, try using just the center mic or just the outer two mics.
  • The more mics you have open, the less volume you get before there’s feedback. It’s natural to think the best way to pick everyone up would be to hang lots of mics, but that actually makes feedback more likely. Each doubling of the number of open microphones (NOM) reduces the potential acoustic gain (PAG) by 3 dB.
  • Low frequencies are omnidirectional – Bass frequencies from main audience speakers can hit the mics on stage. (Also bass frequencies from the monitors can hit the audience).
  • Don’t position mics where air is blowing – Air blowing into a condenser mic creates a thunder sound. This is true of lavelier and headset mics also.
  • Coil excess cable Cable under mic stands, not where feet go.

Mic usage

• Use mics at the appropriate distance for that mic. The Inverse Square Law shows: Each time the distance between the microphone and sound source is doubled, the sound pressure level at the microphone drops 6 decibels (dB) (an approximation when in a room). Every 10db is approximately half the volume.
• Performers should not cup their hand over a handheld mic ball.
• Coach performers on mic usage as they help set up.
• Mic drop = Mic that might need to be replaced

Mic EQ

• Frequency Range for humans
  • Lows – Bass, Kick Drum, mud
  • Mids – Middle of piano, vocals, violins
  • Highs – S’s & T’s, Cymbal ticks

Rooms tend to favor lower-mid frequencies (mud).

• When the proximity effect of a dynamic mic is combined with room resonance, you get a muddy sound (emphasizing lower mids). 
• Intelligibility suffers. 
• The natural inclination is to turn it up, which makes louder mud and can make intelligibility even worse. 

EQ vocal mics for a natural voice sound

• Turn down lows for vocal mics – sounds better AND hinders low-end feedback
• Goal – Sounds so natural, you have to turn it off to prove it was on
• Notch (selectively reduce volume of) ringing frequencies as needed for feedback suppression.

Monitor Routing for Mics

• Don’t send choir mics to stage monitors.
• Don’t send ear-mics to stage monitors.
• Don’t send lavalier mics to stage monitors.
• Monitors need handheld vocal mics, pitch and rhythm (track).
• Monitors don’t usually need piano at the elementary level.
• Don’t send low frequencies to monitors (if you have the ability).
• Send enough track for singers to be confident, but not enough so the mics can hear the track.

Wireless Mics

• Place wireless receivers for line of sight to the antenna(s).
• Avoid Breath pops. Position mic element away from air flow.
• Illegal wireless frequencies can cost $16,000 per day in FCC fines.
• Physical failure is more likely with some brands than others. My anecdotal observation:
  • Samson has been the worst due to cable failure and adapter failure.
  • Audio Technica sounds good and seems to hold up but more expensive
  • Countryman sounds great but the cables become brittle and break more quickly than most and they are 2nd expensive.
  • DPA is the sound quality standard but $900 per mic
  • Springtree Media has mics with good cables that sound better than DPAs. – For every mic sold, they donate $20 to water projects. This is what I buy for my own rig now.

We can give your system some love

Full System Calibration & Documentation

• Setting all EQ with calibrated, reference, measurement equipment so speakers match the room
• Setting optimum levels in every stage of the audio signal path
• We will teach you how to Gain Stage your own system
• Set up routing to monitors for you
• Teach mixing principles to you and/or students and volunteers
• Cable repairs
• Fully document the system so we both know the signal paths and I can offer free remote help more easily.
• Cleaning dust without changing important settings
• You get a report of fixes completed and recommendations (no upsells)

Email help is free and I always give sound advice!