The Belonging Co., Nashville, TN; image: Diversified
If there is an opportunity to upgrade or even get a new sound system for your church client, what is the best approach to handle this challenge? One sound expert, and church tech, from Singapore's New Creation Church suggests this structured approach.
Share your take on his ideas in the comments field, below.
1-Gathering of high-level requirements
The church representatives can begin by writing down the high level requirements. For example, is the worship service for live audience only or also for broadcasting through social media to on-line audience? The sound system requirements depend heavily on the style of worship. Is it a traditional or contemporary worship service or both?
Providing an exhaustive listing of the sound sources is important. Questions to ask include, but are not limited to, how many vocalists will there be, and whether or not they will be using wired or wireless mics, what is the size of the choir, what are the other microphone requirements (i.e., wireless handheld, head-worn or lectern) for speech-related events like sermons and program announcements, what are the types of musical instruments, inputs from other sources, such as computers, CD players, etc. Also, what are the monitoring requirements, e.g., in-ear monitoring, wired or wireless, stage monitors? Is there a need to feed the audio and video to other rooms within the building in the event of attendance overflow? Recurring requirements for special events such as Christmas and Easter are also to be included. Other useful features such as multi-track audio recording and virtual sound check for sound training will need to be considered.
This may look tedious, but this early stage of defining the needs and wants is as critical as the design of the sound system since the final success depends on the fulfillment of all identified end-user requirements. Since the sound system is expected to meet both the current and foreseeable future needs, these ought to be included in the list. An excel spreadsheet can be helpful in documenting these requirements, and this should include constraints such as budget, space for FOH (front of house), sound booth, etc.
The early stages of defining the church teams' needs and wants is as critical as the design of the sound system itself.
2-Translation to sound system requirements
The sound system designer can then base on the above high level requirements and translate to sound equipment requirements such as types and quantity of microphones, DI's, stage boxes, mixer I/O (input/output) channel count, power amplification, loudspeaker system, cabling requirements, IT infrastructure, electrical power requirements etc. This is by no means a single direction workflow. Clarifications, suggestion of possible options based on past experience and projects, and trade-off discussions with the church representatives mean that there will be considerable information and requirements refinement flowing back and forth. Hence, it is important that sufficient time be allowed for this process. This reaches the steady-state when the rate of amendments has tapered off finally.
It may be worthwhile to note that while contemporary praise and worship segments may be the most complex for audio mixing and therefore drive most of the sound system requirements, it is the speech-related part of the program, such as preaching, testimony, and announcements, that takes the lion's share of the worship service time. Therefore, it is prudent to pay particular attention to mic'ing requirements for the sermon.
If the requirement is for the live online audience, in addition to the live audience, the recommended solution is for the sound system to be able to provide a separate audio mix from the front of house mix to cater to the online audience. It can take the form of a separate audio mixer just for online mixing. Alternatively, in the case of a simpler system, a single audio mixer with separate auxiliary output can be utilized for online mixing through the use of a separate control surface or tablet. Since the purpose of the online mixing is to re-create the live feel, ambient mic'ing is normally employed to include live audience responses.
The requirements for online services are different from live services. For live services, the audience gets the sound mainly from the loudspeaker system and some sound directly from the stage. If the loudspeaker system is properly designed, there should be more than sufficient margin for the loudspeaker system to reinforce the sound to the targeted SPL (sound pressure level). The dynamic range is expected to be wide. For example, during a speech-dominated event, the SPL may hover from the high 60’s dBA, whereas the loudest segments of the praise and worship can reach 90 dBA or beyond. The dynamic range could easily be 20 dB or more between speech and loud music.
A separate audio mix with more limited dynamic range is required to provide the online audience with the best sound experience.
In contrast for online audiences, the limit for digital transmission is the maximum digital audio signal level of 0 dBFS (decibel full scale). As to how loud the sound is that they actually hear, it depends on the volume setting of their home loudspeakers or headphones. In many cases, online users hear the sound from their computers' or mobile devices' loudspeakers. In the home environment, the comfortable sound pressure level is usually much lower than in live sound venues. The dynamic range is also much more restrictive for the home environment. Therefore, a separate audio mix with more limited dynamic range is required to provide the online audience with the best sound experience.
Compression is used to achieve this reduced dynamic range. The input channels for vocals and many of the musical instruments are usually compressed with a low compression ratio (e.g., 2:1 or 3:1) along with a high compression ratio, e.g., 6:1, at a higher threshold that acts more like a limiter for the master channel. This is to maximize the digital audio level without clipping, and yet enable it to meet the program loudness in terms of LUFS (loudness unit full scale) or LKFS (loudness k-weighted full scale) in accordance to the respective social media guidelines. In this regard, many users find that digital mixers together with loudness meters are well suited for this purpose. If computers are used to broadcast to social media, free loudness meters such as the Orban meter (https://www.orban.com/meter) can provide an accurate live audio level monitoring for transmission via Zoom or to social media platform.
Shown here, an Orban meter in live monitoring mode, providing comprehensive metering for loudness (LKFS) as well as signal peak monitoring (dBFS).
In designing sound systems for church applications, sound system reliability is one very important criterion. Church services are expected to go on uninterrupted. One-off reduced functionality may be acceptable, but not total system failure. A sound system can fail to function due to a variety of reasons, such as incorrect operation, and accidental incorrect audio mixer or processor I/O routing, power supply-related issues, or actual component failure. It is not unexpected that when an issue is discovered and identified, there is usually not much time left before the church service starts. The church sound team should be able to get in contact with a relevant party, such as the consultant or manufacturer, for application engineering for a suggested fix or a temporary workaround solution. During the design stage, there is a need to comb through the entire signal flow diagram to figure out the possible workaround solution should any one of the components fail. Such workaround solutions should be planned for and rehearsed upfront to reduce the time required to restore the sound system to partial or full functionality.
3-Acoustics considerations
Another important thing to note is that sound does not come only from the loudspeakers. The loudspeakers interact intimately with the venue acoustics space. Disturbance from external or internal noise sources can distract the congregation from fully engaging in the worship service. Therefore, the acoustics requirements of the venue must also be considered. There are specific acoustic requirements, such as RT60 (reverberation time at 60dB change) and STIPA (speech transmission index for public address system), that are necessary to achieve good speech intelligibility. An acoustic consultant is engaged for acoustic treatment to meet target reverberation time, reduce slap-back echo, minimize sound transmission from external sources and sound transmission from the venue to the neighborhood of the venue, minimize background noise, such as from air-conditioning systems, to meet certain noise criteria ratings (e.g., NC-30) and reduce other structural-borne vibration and noise.
4-Loudspeaker system optimization
Loudspeaker systems need to be optimized to meet critical performance goals, such as loudspeaker coverage. This include maintaining good tonality throughout the venue seating area, as well as minimizing the sound pressure level spread between the front row seats and the back row seats. The loudspeaker system designer can start off the loudspeaker design using a computer simulation program. When the intended design goals are met, critical parameters such as loudspeaker positioning and aiming angles are noted for implementation. The loudspeaker coverage can be verified on-site using acoustical measurement tools such as dual channel FFT (Fast Fourier Transform) like Smaartlive. Further optimization, such as level, equalization, time delay for subwoofer alignment, etc. can be carried out and stored in the loudspeaker processor. Loudspeaker system optimization is a critical step not to be missed, even in a one-off rental venue, to obtain the best possible sound from the loudspeaker system. The loudspeaker system design and optimization has to be carried out by highly trained and qualified personnel.
5-Operation
The operation of the sound system includes a sound equipment check, mic'ing, audio mixing, monitor mixing, troubleshooting, problem-solving, and prevention of future issues. This responsibility lies mainly with the church sound team. The complexity and scale of this operation is enormous and cannot be fully expounded upon within this short paragraph. A proper sound training program is required for the passing of knowledge and skills from the consultant, systems integrators, system designers, and sound equipment application engineering to the church sound team. Regular sound training programs are useful in bringing up suitable new church sound volunteers to participate in designated roles so that the Gospel, whether preached, sung, or played, can reach out to all of the intended audience with minimal distraction.
Summary
This systematic approach is not only applicable when the sound system is being upgraded or replaced. This same structured approach is valuable when planning for the required sound support for occasional special church events at off-site venues.
