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The H.I.S. System
Written by Joseph DeBuglio, 2000
Edited by Dave Gordon, Eagle Sound and Acoustics 2004
The Highly Intelligible Church Sound (H.I.S.) System Standard is based on the following goals:
- Each standard must be applicable to over 90% of the churches within the church community.
- It should establish a foundation for a sound system which can be built upon for future growth.
- The system should have all of the basic features designed into the system, ready to provide sound for all of the most common church events from worship to weddings, funerals, concerts and drama.
- It must use combinations of equipment, microphones and speakers which are relatively noise free when inserted into the system.
- The combinations of products must be affordable. The target cost of an entry-level sound system should be about $35.00 to $45.00 per seat installed.
- It must satisfy people with average hearing loss and benefit those with hearing aids. It shall be understood a hearing assistance system is needed for those whom you have to raise your voice to in normal conversation.
- Easy to operate with the least amount of instruction.
- Have enough gain so a person can stand in a comfortable position. This generally requires a micing distance of 18 inches.
- To work within generally accepted guidelines of coverage, intelligibility and performance standards, not yet made official by any secular professional body.
The H.I.S. System also requires certain acoustical considerations. People have been trying many sound system designs to avoid dealing with the acoustics of a space. The records show more failures than successes. Until recently, many people thought an audio system could sidestep the laws of physics. This is no longer the case. The following is a list of acoustical conditions which must be met for your sound system to be effective.
- The room must be free of echoes.
- The room must be free of flutter echoes.
- The RT60 should not exceed (on average) 2.2 seconds.
- The RT60 should not be less than 1.3 seconds.
- There should be no standing waves from any angle (side to side, front to back and floor to ceiling).
- The NC of the room shall be below 40dB.
It is generally understood each violation of these acoustical conditions will limit the performance of any sound system in proportion to how serious the acoustical problem is.
The H.I.S. System Details
- The average working distance from a regular dynamic microphone before feedback - 18 inches (in a room with NC 40 or lower).
- Maximum working distance from a regular dynamic microphone before feedback - 30 inches (in a room with NC 40 or lower).
- Average sound pressure coverage within the seating area +/- 3dB
- Intelligibility score +/- 2% of 92% in all seats. A Computer should be used for this or you can use the oral speech test.
- With your eyes closed, turn your head to the source of the amplified sound. When you open your eyes, you should be looking at the person speaking or in their direction from any location within the sanctuary.
- At 18 inches from the microphone, have enough sound pressure level (SPL) to be around 25dB above the room noise or have an average SPL of 66dB in all of the seating. The NC of the church has to be below 45dB to reach this goal
- The sound system must not increase the reverberation time of the room.
- The sound system must not degrade the performance of the organ or compete with congregational singing when a microphone is left on.
- The sound system must allow the sound operator to quickly change controls without people in the audience noticing the changes.
- The sound system must be stable with 3 mics open and micing at 12 to 16 inches without feedback.
- The sound system must not introduce a signal or noise when using the maximum mic gain for a single open microphone. This means no hissssss or radio stations.
- The sound system must not introduce a signal or noise with 4 open mics and micing at 12 to 16 inches without feedback. This also means no mixer hissssss
- Have enough SPL in the sound system without distortion so a person can be heard clearly when needing to speak to the audience during congregational singing.
- To place the speaker system in the "sweetspot" of a sanctuary to achieve the highest level of intelligibility and best coverage.
- All microphone lines must be balanced type II (two conductors, a ground wire with tin foil shield) using a 3-pin connector. All lines shall be wired - pin 1 ground, pin 2 hot signal or positive signal, pin 3 cold or negative signal.
- All microphone lines must be continuous from the platform to the mixer position without any breaks. Do not use multi pair cable or snakes.
Needs and Wants
Next is filling the needs of the basic church system.
- Provide a minimum of 1 mic input for every 60 square feet of the pulpit/ platform/ alter area. This will ensure enough mic locations for the choir and all special events.
- Provide an amplifier with a minimum of 1/2 watt per person. Some churches may require 2 to 8 times more power per person.
- Provide a tape player and/or CD player for playback.
- Provide a separate tape recorder for recording services. This prevents a feedback loop which often destroys sound systems. Many churches use tape sales to fund other sound system expenses.
- Provide a Constant "Q" 1/3rd octave equalizer for every live mix (mains, floor monitor, choir monitor....).
- Provide the option for floor monitors without replacing the mixer.
- Provide the option for choir monitors without replacing the mixer.
- Provide the option for musician monitors without replacing the mixer.
- Provide the option for separate signals from the mixer for tape recording, distributed system (nursery, offices, washrooms...), broadcast output for TV, cable or video, and hearing impaired systems.
- Mixer must have Pre Fade Listening (PFL) on each channel.
- Mixer must provide 48-volt phantom power for condenser microphones.
- Mixer, amplifier and equalizer should always be separate units. - (No Exceptions).
- All components must have electronically or transformer balanced inputs and outputs - (No Exceptions).
- Mixer must have separate Left and Right (Live and Record) master output faders.
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