With this three articles dedicated to installations we want to get deeper understanding on a specific topic, the acoustic installation, that is often given for granted, but still hides numerous dangers.
It is not our intention to make an academic report nor to give definitive solutions, but just to give our experience in the distribution of indoor and outdoor speakers, their installation and the optimization of a sound reinforcement system to all of those that find themselves facing the choice – and the expense – of installing a professional sound system.
In this first episode we will cover commercial facilities, such as shops, beauty salons, and shopping centres, while in the following episodes we will focus on recreational environments (bar, lounge, pubs…) and the “conferencing” world, like meeting rooms and congress venues.
Each of the spaces above, even if similar for some aspects, must optimize diffusion based on specific requests and needs, that are not always the same.
Let’s proceed in order…
PUBLIC ADDRESS SYSTEMS
The Italian fantasy has named this kind of installations in all manners, “rediffusion”, “sound diffusion system”, “ambient music”, where the English world, usually more pragmatic in definitions, indicates these systems as “public address”, referring specifically to a sound system dedicated to the public, whatever it may be.
But what are the specifications such system must have, and why is it substantially different from a live music system?
With this series of articles you’ll probably find many of the answers you’re looking for.
First things first we must embrace the proper definition, so from now on we’ll use the term Public Address, internationally recognizable.
A PA sound system is an electronic system including various devices such as microphones, amplifiers, and speakers, and that is installed with the purpose of diffusing a music program, or amplify the volume of human voice, a musical instrument, or any other source that needs to be received clearly by the public.
At this point, following this description, we want you to focus on one thing: PA systems are not only used to deliver music to the audience, but they are also needed to deliver informative messages or, even more important, safety messages, in sinergy with EVAC systems. These topics will be further discussed in the next episodes. One of the main features - strongly requested by designers and architects – is for the system to be hidden, “not seen”.
That’s why contractors often use ceiling speakers, to be installed in drywall structures in non-invasive positions.
For the same reason, cables, amplifiers, and other devices, are never to be shown and are often conceiled in specific areas, accessible only to staff.
Audio systems installed in shops, beauty salons, and similar, have the purpose of entertain people and make more comfortable the stay.
It has been proved that music diffusion can sensibly influence the choices of the customer that, even if unconsciously, pays always attention to the music program.
We could then assume that the main requisites for this kind of environments are:
Let’s start from point “1”, the one we prefer and that, sadly, too often is given for granted.
How many times you stumbled upon “cracking” speakers, visibly in trouble, undersized, or even a sound well too rich in low frequencies, resulting confused and annoying?
Im agine how this low quality can result unpleasant to the public or even dangerous ofr the staff of the shop.
In this case the number of the speakers in relation to the area of the facility and the positioning of the subwoofer are essential. Let’s remember that the sound of a system is also made by the environment, made of walls, ceilings and materials that enclose the system itself.
In the same way, great importance is given to the integration of the systems in relation to the style and context in which they are installed. There are substantially two paths:
The most common technique used until now has been that of hiding the speakers, therefore bypassing the problem of the aesthetics.
In the last few years though, especially in some more fashion oriented contexts, speakers have become part of the scenery, adding value in terms of style and design.
In this case it is also very important that the speakers are well built, with extreme care for shapes and colors. And the products on the marker, deal with it, are not all the same.
concerning point “3” – ease of use – it i salso important how this aspect is to be taken in consideration.
In the end, those that will use the system have little to no interest in the technology behind the scenes and, in the majority of the cases, it’s best for them not knowing.
“Few functional controls”, that’s what the end user needs. It is the job of the contractor and the project manager to cope with the setup and alignment of the system, leaving to the user just a couple of controls: volume, source selection, microphone mute and, in exceptional cases, some limited EQ.
In more complicated installations, wall mounted touch panels can be used, showing these few controls.
PROJECT AND INSTALLATION
When starting a project from scratch a sound system in a closed environment – let’s take the case of the shop – first of all we must consider the volumes and dimensions of the location and, if possible, get a CAD drawing to be used in addition to an acoustic prediction software.
The choice of the number and positioning of the speakers must be made following specific criteria, so that the entire area is washed coherently, and with adequate pressure. La scelta del numero e del posizionamento dei diffusori acustici deve infatti essere fatta con un criterio ben preciso ed in modo che tutta l’area venga sonorizzata coerentemente, in maniera omogenea e con una pressione adeguata. How do i get the right positioning and distancing of the speakers?
Usually the number an positioning of the speakers are dictated by the radial dispersion of the speakers themselves, in addition to the effective number.
The more a source has a wide dispersion, the easier it will be to cover larger areas. The direct consequence is that you’ll probably need less speakers. So far so good, you’d say, and in some cases it is better to have “wider” speakers.
However, speakers with wider dispersion on a large acoustic spectrum, tend to be less efficient in terms of acoustic accuracy and precision in relation to those with a narrower coverage. So it is once again important to well understand what you need in relation to result we want to achieve.
Another important aspect is the interaction between the speakers. In this case we’re dealing with one of the most fierce laws of acoustic physics, telling that if two speakers interfere in phase with each other, you could encounter masking phenomena (comb filtering) or unwanted amplifications in a certain range of frequency.
Your acoustic prediction software will help in this case, predicting on paper (on screen actually) these inconveniencies.
In some situations more than other, when we project a sound reinforcement system for commercial facilities, what we need to pay the most attention to is acoustic comfort. The purpose is ofter that of entertain customers and public, respecting at the same time the commercial dynamics of the shop or centre.
This means that the sound must never be:
Acoustic comfort is defined as a condition of psychosomatic wellness in relation to the place and the activity happening in it, and this definition is described by the three aspects above elencated.
One of the worst enemies of acoustic comfort is for sure reverberation. Reverberation is the acoustic decay when a source is turned off and the sound bounces on the surfaces of the room. Reflection control is possible by calculating the time of reverberation , RT60, defined as the time taken by an impulsive noise to decat 60dB.
Il controllo delle riflessioni avviene attraverso il calcolo del tempo di riverbero, RT60, definito come il tempo necessario affinché un rumore impulsivo, interrotto bruscamente, decada di 60 dB. The formula is RT60 = k*(V/Sa), where k is constant = 0.161 if the unit used is the metre, and 0.049 if expressed in feet. “Sa” is the total coefficient of acoustic absoption expressed in Sabine and it’s the sum of the surfaces of the room times the coefficient of acoustic absorption. To obtain it there are many methods, the most common is the frequency “sweep”.
As you may have understood from this first article, making an installation to deliver a music program in a commercial facility doesn’t mean placing randomly speakers and subs.
The acoustic installation, in this case, differs from the usual listening situation like, for example, a home stereo where the listener is still in one place. In a commercial activity people move, interact with the environment and the staff, and at every moment must feel welcome and cuddled by the music, without being bothered and annoyed by it.
To give the right value to your money and achieve concrete and long lasting results, you need to rely on professionals that proceed with the following steps:
With this kind of contents – as mentioned before – we want to give our unconditionate support to the cause, but we cannot fail to mention that the Helvia catalog has a wide range of professional solutions dedicated specifically to this field. At the same time our team of specialists can take in charge all the phases of the job, from the first visit to the analysis, up to the installation itself.
Provided by Encore Agency