Article on Acoustics

  • This UK site works with contemporary church musicians. This excerpt from "the other side of the fence" does offer reasons why Catholics in dry acoustics will not sing and participate.

    Within this article are clear descriptions of what "acoustics" are and how they affect speaking and singing.


    Any time we create sound in an indoor environment we can split what we hear into two specific categories: the direct sound which travels straight from the source to the listener, and the reverberant sound which is made up of all the copies of that sound which reach the listener after having bounced off one or more surfaces in the venue. Depending upon the size of the venue and the materials it is made of reverberation may die away very quickly, or it may linger and last a long time.

    Reverberation is not a bad thing in and of itself; it is a natural product of creating any sound in an enclosed space. In fact if you ever find yourself in an enclosed environment without any reverberation (such as an anechoic chamber, used for conducting precise scientific measurements of sound sources) it can feel quite unnatural and uncomfortable. Most of the time we are not consciously aware of reverberation, it is something we naturally expect to hear and our auditory systems process it entirely subconsciously. However sometimes reverberation can cause us issues if it is not appropriate to the venue or application.

    Problems with reverberation can go one of two ways:

    Too much reverberation will smear all the short, sharp transient sounds which are critical to speech intelligibility (think about the T’s and P’s) and make it harder to understand what is being said. Likewise percussive or strummed instruments which are central to many forms of contemporary worship have very short transient components that will lose clarity and impede the clear expression of rhythm, making music feel cluttered and messy. At the same time, the length of the reverberation time means that sound energy stays in the venue for longer and builds up to greater levels, this can result in worship feeling overly “noisy” and is a common cause of the “it’s too loud” complaint. In a reverberant environment more of the stage noise will bleed out into the front of house sound so it also becomes harder for the sound person to control overall volume levels from the mixing desk.

    In contrast, too little reverberation will lead to a very crisp, clear sound, but makes the venue feel very dry and uninspiring to sing in. This may be ideal for venues which are focussed purely on speech or contemporary music performance, but in churches where the worship is a participatory experience your congregation will begin to feel very exposed and have a tendency to hold back from fully engaging in the worship. Because of the participatory nature of church services we generally aim for a slightly longer reverberation time in church venues than we would in other contemporary performance oriented spaces, it is particularly important if you are engaging an acoustic consultant that they understand this – for example a consultant whose experience may lie predominantly in theatres or concert venues may not be the ideal person to design the acoustics for your church.

    At SFL we believe that around 1.4-1.6 seconds is about ideal for most churches, though this is venue and application specific so is not a concrete rule. Slightly longer reverberation times can usually be tolerated in larger venues or venues where more traditional forms of musical worship are the dominant mode. As some interesting references, many classical music venues are designed for slightly longer reverberation times in the order of 2-2.5s, whilst building regulations for classrooms and lecture theatres in the UK call for a reverberation time of no greater than 0.8s. Given the diversity of programme material in the typical church meeting the 1.4-1.6s target sits quite comfortably in the centre ground of these figures.

    There is a commonly held belief in certain circles that cathedrals and other large church buildings have the ideal acoustic. I’ve lost count of the number of times I’ve been told that a church has a “fantastic acoustic”, which usually means it has quite a long reverberation time. Cathedrals in particular tend to have very long reverberation times as they are both very large spaces and tend to be constructed out of lots of very hard and reflective materials such as solid wood and stone. According to figures from the University of Salford, St Paul’s Cathedral in London has a reverberation time of a whopping 13s. This appreciation of acoustics – that the “cathedral-like” reverberation is the ideal – is not necessarily wrong, but it is overly simplistic. The long reverberation times experienced in cathedrals would have been very helpful for historical forms or worship which were often choral or organ led, in particular a more reverberant environment will help unamplified voices carry further. However for a church trying to deliver more contemporary worship styles or relying upon electro-acoustic amplification rather than purely on the acoustic to aid propagation of the spoken voice the “cathedral” feel will ultimately form an impediment to sound quality and listener comfort.