Introduction
Frankfurt Musikmesse will see the first beta release of a new Martin Audio software tool called DISPLAY™ (DIrect Sound Prediction of Line ArraYs). The program is intended to equip users of W8L Series Line Arrays with a powerful yet simple to use analysis and design virtual 3D environment. With the aid of DISPLAY™, guesswork regarding coverage and SPL is removed, enabling confident rapid deployment of arrays in any venue. This software is the first fruit of the dedicated software development section within R+D and establishes a framework for the future.

Features
2D and 3D modes
Allows new users and particularly those who use ViewPoint™ to rapidly generate venue models.

OpenGL rendering
Smooth, fast and precise manipulation of views.

SPL Distribution
Variable spatial and frequency resolution over different planes.

Frequency response
Resolution down to 1/36 oct, smoothing up to 1/1 oct at user defined microphone position.

Polar plots
Multiple frequencies at a user defined distance from the geometrical center of the array

Comprehensive rigging/setup information
All the information needed to deploy the arrays, including mechanical, safety, patching and controller parameters.

Environmental effects
Temperature and humidity dependant air absorption.

Standalone Operation
Efficient data storage, accurate interpolation and fast calculation enables DISPLAY™ to run well on any modern laptop without any complicated client-sever requirements

Calculation Method
The complex (magnitude and phase) sound pressure of each component of each box is measured over a sphere of radius large enough to be deemed far field for that component. This data is stored locally to the program. The directional point source technique is then employed using a fully complex interpolation scheme. The complete soundfield is formed from the complex summation of all component contributions. Further information regarding the calculations can be found in the ‘technical area’ of the Martin Audio website under the ‘Papers’ heading.

Case Study : Royal Albert Hall
As an example application we have selected a simple deployment of W8Ls in a ‘difficult’ venue. The first step is to approximate the venue with complex planes (complex planes are defined by 3 or more coplanar vertices).

With this in place we can consider the arrays. 2 columns of 12 either side of the stage angled outwards seems a reasonable starting point. Figure 1 shows the 1/3 oct 4kHz band SPL distribution. It is apparent that the splay between the columns is too great and a reduction of this splay produces better results as can be seen in Figure 2. In this plot we notice that coverage on the periphery of the audience planes of the highest balcony should be improved. A way to achieve this is to pull both arrays back. Figure 3 displays this distribution which is respectably even over a large area. An informative overview of the venue is shown in Figure 4 where 4 separate views are displayed, this time at 8kHz.

Using spot frequency response analysis at various positions in the venue we can assess the variation of the output. Figure 5 depicts the frequency responses at the microphone positions marked by circles in Figure 3. We can see that the responses are smooth and similarly shaped, indicating a consistent sound throughout the venue. Another interesting view of the output is the aligned polar (at a distance of 20m) shown in Figure 6, where different frequencies are plotted on a polar graph aligned to the array axis. Once again the smoothness and controlled dispersion characteristics are apparent.

This iterative approach to the sound system design can be refined further, the above being an illustration of what is possible in a short time. All the splay angles are determined automatically and controller presets are standard ones. This fulfils an important aim of ours which is to not involve the user in low level details such as cabinet splay angles and let the software do most of the work. Full access to all the parameters in the controller-amplifier-loudspeaker chain is available to expert users or those wanting to learn. If space permitted in this article, we could demonstrate further tweaks to this venue by introducing small eq changes to the controllers.

Conclusion
The advent of line array technology has witnessed a new level of soundfield control which, in order to be fully harnessed, requires partnering setup software. This is due to the non-intuitive nature of some aspects of line arrays and the ability of achieving similar coverage goals with quite different looking arrays. For instance, whilst it is possible to achieve a particular dispersion using purely acoustic techniques, this may dictate an array that is too big and interferes with other constraints such as sight line requirements. What is needed in this instance is a smaller array driven intelligently. Factor in variable environmental conditions and the case for a flexible system approach using DISPLAY™ is unassailable.

It is becoming increasingly common for authorities to require information about SPL beyond the perimeter of an event - granting licences only when the nuisance impact can be assessed. DISPLAY™ has already proved that it is capable of fulfilling this requirement during internal testing with some users.

As a powerful yet simple to use system analysis and design tool, DISPLAY™ is destined to become central to the user training activities of the Martin Audio applications engineers.