26 Jun Mark Bliss Noise-Con 2013 Presentation
BKL Partner Mark Bliss prepared a paper and a presentation for NOISE-CON 2013 Denver summarizing two music-related assessments we performed for the City of Vancouver planning department. These detailed studies were performed over a 5-year period, as the related projects developed, to assess the acoustic viability of a proposed civic plaza from two points of view:
- The paying audience
- The surrounding existing and proposed residential neighbourhoods
Please feel free to read the paper here.
It was a very informative and valuable conference, and we were proud to be one of the presenters there. Here is a short version of Marks presentation:
The City of Vancouver’s downtown has one of the higher neighborhood population densities in North America, so one can imagine that significant community noise impacts would be commonplace.
The City prepared a business model to develop a new outdoor civic plaza, adjacent to land with proposed new residential towers. A flexible plaza venue was proposed but the viability of the space depended on an assumed number of revenue generating events per year. Note that revenue generating events at outdoor plazas tend to be of the noisy type! City staff acknowledged that the proposed rezoning for adjacent residential may conflict with the desire to construct a new outdoor civic plaza and decided to study potential noise impacts in detail including best practice mitigation options.
- Developers Want: new high-rise residential
- City Wants: new ~2000 seat outdoor performance venue with 30+ performance primary events/year on same property
- History of complaints with previous outdoor venue at that location
- Proposed plaza site exposed to road traffic noise and concerts and sports events at BC Place
- City proposed conducting detailed acoustic study to determine viability of business case
Mark performed a detailed study with the assistance and direction from the City of Vancouver to try to improve the acoustic compatibility as much as practically possible. However, there are always conflicting interests and compromises that need to be made and noise mitigation often costs money. In this case, the competing interests were:
- Paying audience wants to clearly hear concert above the residual sound
- Mixing console operators generally have absolute loudness targets at the front-of-house (FOH) mixing desk
- Surrounding existing (and future) residents don’t want to be disturbed by numerous performances throughout the year
Detailed computer software models were developed using Cadna/A and Odeon to model the exposure of the site to environmental noise and the propagation from a variety of sources to the surrounding neighbourhoods, including:
- Pop/rock concerts
- Jazz/blues concerts
- Symphonic concerts
- Recorded music performances
- Background music
- Amplified speech
The Odeon model incorporated high-directivity line arrays and subwoofers in an attempt to minimize the potential impacts on the community. Results were calculated in terms of the percentage of time where the following criteria would be met:
- The audience would not be distracted by road traffic or BC Place noise
- The noise bylaw would be met outdoors at the surrounding existing residences
- A higher outdoor noise level would be met at the surrounding future residences, acknowledging that a higher level of protection could be designed into the building envelope using available construction techniques
Even with best practice techniques used around the world, we found that this site was not compatible for typical paid performance events such as pop/rock or symphonic concerts: either concerts would be too loud for residents or the environmental noise would be too high for the audience. Results were also presented to and supported by user groups (event organizers and technical experts) who tested and agreed with the study’s assumptions and conclusions.
An acoustical consultant’s intuition tells them that open air concerts are not compatible in noisy areas or adjacent to residential land use. On the other hand, when there is a will there is often a way. In this case, the City of Vancouver’s design and flexible use program objectives for the plaza were directly at odds with the design interventions that would have been necessary to adequately address the acoustical problems, leading City staff to recommend changing the assumed plaza programming to a predominantly small scale event/performance focus.