The Journey Begins…
In February 2020 we were appointed by the MOD and their contractors, on behalf of the Household Division Army Music, to conduct a review of an acoustic upgrade project. The primary goal was to reduce noise levels in their rehearsal rooms. However, upon evaluating and discussing the proposed solution with the Quartermaster (QM), we agreed it was not suitable. Our ideas were deemed more effective in terms of protecting musicians. As a result, we embarked on the task of proposing a new design approach that would prioritize Stage Support, the acoustic parameter that enables musicians to hear themselves clearly without exerting excessive force on their instruments, consequently, they can naturally protect themselves from high levels of energy .
We conducted tests on Room number 2 (as the other 2 were identical), and the results were quite interesting. The average reverberation time was just above 0.5 seconds, with a distinctive behaviour observed between 1 and 2 kHz frequency bands, which made the room feel aggressive. One contributing factor to this behaviour was the wrong distribution of absorption, with a highly absorptive ceiling and floor, and wood slotted walls along the perimeter. Additionally, the shape of the room was strongly influenced by corner reflections, resulting in uneven sound distribution throughout the space.
Designing the Upgrade
Adding more absorption, in theory, would help to reduce noise perception but also will remove vital information coming from the room and it would increase the sound masking effect between musicians forcing them to raise their individual levels as they are not going to be able to listen themselves clearly.
The primary objective of this integrated design is to create an environment that facilitates a positive psychoacoustic contribution from the room, benefiting both the musicians and the conductor. By implementing this design strategy, we aim to achieve a flattened frequency response and enhance the overall definition within the room, while minimizing any harshness caused by high levels of sound energy. This will enable the performers to gradually adjust to lower sound levels, ultimately reducing the risk of hearing damage while maintaining the quality of their performances.
A valuable addition to support musicians was the inclusion of specially designed acoustic shields for Wellington Barracks. These shields will work in combination with the robust diffusive system designed, further enhancing the overall acoustic environment. The shield effectively protect a musician from a trumpet player by reducing 8.5 dB and also scatters the sound. A perspex shield can only achieve a 2 dB reduction and reflects the sound on both sides.
Dealing with diffusion – Detailed design
Continuing with our analysis and incorporating the valuable insights of Prof. Jaime Delannoy, our collaborator and renowned expert in Acoustics with a PhD in the field, we found that the original conditions of the rehearsal rooms at Wellington Barracks lacked sufficient diffusion and useful first reflections.
To address this issue, we strategically implemented four different systems of diffusion. The percussion section was allocated a 2D diffusion system to increase residual absorption and provide smooth reflections throughout the rest of the band, with particular emphasis on the back of the drummer. The “conductor” wall, or front wall, was equipped with a 1D diffusion system to enhance horizontal reflections near the conductor and capture the entire width of the room. Additionally, the side walls were designed to create diffusive areas at the listening height and generate late scattered sound waves effectively creating a sense of increased width within the room, despite its square shape.
One of the key objectives of the new acoustic strategy was to recreate the immersive atmosphere of a live recording room. However, considering the unique context of a rehearsal room, it is crucial to be able to discern and distinguish each instrument individually, while also being able to clearly perceive the instructions from the Band’s conductor. This is particularly important as the conductor needs to be able to perceive and respond to changes in dynamics during the rehearsal process.
Installation and final tests at Completion 2021
In June 2021, we successfully completed this project with outstanding results. Our main objective was to ensure minimal alterations to the reverberation time of the rooms while simultaneously addressing and rectifying issues such as frequency response sharpness and uneven sound distribution. We successfully developed and implemented this solution by integrating custom-made products.
We are delighted to report that we fully achieved all three objectives.
By striking the right balance, we were able to preserve the same strength of the space while significantly enhancing the overall sound quality and ensuring a more safe listening experience for all.
R. Sanles
MIOA-MAES
Memberships
Member of the Institute of Acoustics of Great Britain
