Aportes de los mecanismos de participación ciudadana en la supervisión y control de obra

As discussed in Section 2.5, previous studies into stage acoustics with in situ musician sur- veying and in situ measurements have had mixed success in meaningfully quantifying the subjective preferences of musicians. There is a wide range of possible explanations for this, generally relating to the limitations of the studies. First there are a number of issues in previous studies which have impacted upon the reliable collection of subjective data from musicians, such as the following issues:

• In previous studies, where musicians have not been surveyed during a touring schedule, the repertoire played by musicians in different auditoria could be variable, meaning musicians cannot make direct comparisons between auditorium’s acoustics.

• In past studies, where musicians have not been surveyed during a touring schedule, rea- sonably long time intervals have existed between the musicians experiencing different auditoria, potentially making direct comparisons more difficult.

• Surveys have frequently been completed from memory, with no recent playing expe- rience in the auditorium, rather than directly after experiencing the acoustics of the auditoria (even though acoustical memory is known to be short [Gade, 2007]).

It is difficult to control the issues mentioned above in order to keep conditions similar between different studies, and generally past studies have taken opportunities to survey musicians when they are available, without strict control of the above factors.

As well as the possible limitations surrounding subjective surveying, another contributing factor to poor correlations between subjective judgments and objective data is likely to be the limited number of auditoria which have been included in past studies. Generally the total number of auditoria included in recent studies has been low, particularly for studies of on-stage acoustics for symphony orchestras, and especially considering the increased com- plexity for a symphony orchestra on-stage compared to a chamber orchestra. The additional complexities include a greater number of different instruments playing on stage (potentially with differing acoustics needs), and a larger stage area being used (potentially with varied acoustics depending on on-stage location).

based on the fact two auditoria had very low reverberation times. Cederl¨of[2006] considered only five auditoria, and used five different orchestras for the assessments. van Luxemburg et al. [2009] studied seven stages, with the use of a student orchestra for subjective survey- ing. Astolfi et al. [2007] examined five auditoria, again generally using different orchestras to assess different auditoria. Sanders [2003] considered the acoustics of 24 auditoria, and obtained some clear trends in the subjective data, but did not compare to any objective acoustic data, other than reverberation time.

The original studies undertaken by Gade [1989c] to investigate the ST measures (now in- cluded in the international standard for room acoustic measurements) were also limited by various factors, and Dammerud[2009] questions the validity of two of the three studies com- pleted by Gade [1989c]. Gade’s first study involved three Danish orchestras assessing nine auditoria, including their home halls. Dammerud [2009] criticises this study based on the fact different auditoria were assessed by different orchestras, with the exception of one hall (which was regularly used by two of the orchestras)and because it included ‘home auditoria’, which musicians may have been biased towards. The second study by Gade involved one Danish orchestra assessing eight auditoria in the UK. Dammerud[2009] criticises this study as the musicians only played in each hall once, which he considers is not enough experience to give a detailed assessment. Dammerud’s [2009] final criticism is that Gade used audito- ria purpose-built for symphony orchestras and also smaller halls with shorter reverberation times, meaning he altered both auditorium type and stage design simultaneously, making it difficult to isolate which influenced the subjective assessments.

In terms of the limitations related to laboratory experiments (rather than field experiments), Gade [2010] comments that many past experiments have been highly unrealistic and simpli- fied to such a degree that they lack relevance to the actual acoustic conditions in auditoria. However,Gade[2010] does comment that the experimental set up used by Ueno shows much potential for undertaking laboratory experiments with subjective significance.

From past studies it appears that the use of omnidirectional source and omnidirectional receiver on stage as a method to obtain meaningful information regarding on-stage acoustic conditions has its limitations. Studies by Dammerud [2009], Cederl¨of [2006], Astolfi et al. [2007], Berntson and Andersson [2007] and van Luxemburg et al. [2009] are all examples of investigations in which poor correlations between on-stage measures and subjective evalua- tions have been found. In part this may be attributed to the fact the finer details of acoustic response are impacted significantly by the presence of a symphony orchestra (compromising

of 80 musicians) on stage, and thus using an empty stage to undertake measurements results will give a poor indication of the true acoustics experienced by musicians. Whether the effect of a smaller chamber orchestra is significant to on-stage sound fields has not yet been studied.

Additionally, omnidirectional stage parameters cannot consider the directionality of on-stage sound fields. Dammerud[2009] found ratios of stage dimensions (which in part account for directionality) showed high correlations with musicians’ preferences. Additionally, a labora- tory study which considered acoustic parameters defined with directionality was conducted by Guthrie[2014], and found that a parameter defined to assess energy from above relative to energy from the sides may relates to musicians preferences when playing in ensemble. This potential relevance of directionally-defined stages parameters has not yet been tested in a study considering on-stage acoustics in situ in concert halls.