Sensory evaluation of concert hall acoustics - Department of Media Technology

Disentangling preference ratings of concert hall acoustics using subjective sensory profiles

2013-01-09T14:43:24+02:00

Subjective evaluation of acoustics was studied [1] by recording nine concert halls with a simulated symphony orchestra on a seat 12 meters from the orchestra. The recorded music was spatially reproduced for subjective listening tests and individual vocabulary profiling. In addition, the preferences of the assessors and objective parameters were gathered. The results show that concert halls were discriminated using perceptual characteristics, such as Envelopment/Loudness, Reverberance, Bassiness, Proximity, Definition, and Clarity. With these perceptual dimensions the preference ratings can be explained. Seventeen assessors were divided into two groups based on their preferences. The first group preferred concert halls with relatively intimate sound, in which it is quite easy to hear individual instruments and melody lines. In contrast, the second group preferred a louder and more reverberant sound with good envelopment and strong bass. Even though all halls were recorded exactly at the same distance, the preference is best explained with subjective Proximity and with Bassiness, Envelopment, and Loudness to some extent. Neither the preferences nor the subjective ratings could be fully explained by objective parameters (ISO3382-1:2009), although some correlations were found.

References

{bibtex}virtualacoustics/jasa2012_page.bib{/bibtex}

Concert hall acoustics assessment with individually elicited attributes

2013-01-09T14:43:24+02:00

Sensory evaluation, and descriptive testing specifically, requires panels of human assessors who rank and rate the products using their senses. By applying advanced statistical techniques to the analysis of the subjective data, it is possible to reveal the perceptual differences of the products under test. For example, sensory analysis is a common practice in food science.

Similarly, the perception of concert hall acoustics is complex and multidimensional by nature. The music, the conductor, and the performance of the orchestra greatly contribute to the listening experience, and the contribution of the auditorium acoustics itself is hard to isolate with perceptual studies. Individuals have different tastes and preferences, such that the descriptions of perceptual attributes of halls can be ambiguous. In our study [1], a sensory evaluation method was applied to concert hall acoustics assessment to gain a deeper understanding of the perceptual criteria applied to the rating of three concert halls. The final goal was to deliver a better understanding of concert hall acoustics, which aspects are perceived and considered important and how perception could be measured when assessors can simultaneously compare different listening positions and concert halls.

The results obtained with 20 assessors (9 males) include the clusters of individual attributes and the ordination of sound samples (3 seats in 3 concert halls). The main cluster was formed with attributes describing loudness and distance because such attributes discriminate best between the sound samples. Attributes related to reverberation were divided into two subgroups. One of them was related to enveloping reverberance and the other to the size of the space. The samples were also ordered based on definition or clarity where the order is reversed compared to the reverberation describing the size of the space. The three recorded concert halls were clearly distinct from one another. Musical signals seem to provide each a slightly different sensory profile.

Our articles [2-5] tell more details on sensory evaluation methods in the context of concert hall acoustics.

Figure 1: Concert hall plans and receiver positions (Rx) used in the listening test

Appllied graphical user interface for rating the nine samples at a time.

Sensory profiles of studied recording positions.

One result of the individual vocabulary process can be presented as sensory profiles of the studied samples. Here, sensory profiles are formed with attribute groups.

‹ ›

References

{bibtex}virtualacoustics/jasa2011_page.bib{/bibtex}

A study on the benefit of lateral early reflections

2013-01-09T14:43:24+02:00

For this study, reported in two JASA Express Letters [1,2], we created six simulated concert halls that have same monaural room acoustical parameter values according to ISO3382-1. The simulated early reflections are seen in the figure below. Examples of sound samples can be found on the supplementary video.

The first letter [1] that wideband early reflections that preserve the temporal envelope of sound contribute to the clear and open acoustics with strong bass. Such reflections are fused with the direct sound due to the precedence effect. In contrast, reflections that distort the temporal envelope render the sound weak and muddy because they partially break down the precedence. Moreover, the reflected sound has to reach the listener from another direction than the direct sound for open and enveloping sound.

The second letter [2] explains why lateral early reflections were shown to contribute to the perceived distance, envelopment, and openness. Our explanation is that lateral reflections are beneficial due to their increasing effect on binaural loudness—the phenomenon known well in psychoacoustics, but not in architectural acoustics. The reflections from the side are amplified more than median plane reflections, in particular at high frequencies, due to the shape of the human head.

References

{bibtex}virtualacoustics/jasa2011el_page.bib{/bibtex}

Sensory evaluation with individual vocabulary profiling (IVP)

2013-01-09T14:43:24+02:00

Sensory evaluation methods have been predominantly developed in food and wine industry to explore the perceptual characteristics of products, which are hard to evaluate through consumer based preference methods due to huge variation in individual tastes. The acoustics of concert halls is also heavily influenced by a matter of taste. Therefore, sensory evaluation methods are very useful for studying auditorium acoustics due to their ability to extract information often hidden behind preference judgements. With such methods the sensory profiles of concert halls or profiles of seats inside one concert hall can be formed.

Sensory evaluation can also be performed using consensus vocabulary profiling (CVP) where a group of assessors first elicit the adjectives to describe the stimuli and then with group discussions develop a common vocabulary of consensus attributes. CVP approach represents one of the most common tools in sensory science, but is very challenging to tailor to concert hall acoustics studies due to physical constraints. Such process would require the initial development of a consensus language based on visits to concert halls with live orchestras, followed by a second round of visits for attribute ratings. The process would thus be very laborious and would also require expert listeners. To be able to do such studies in the future we are first trying to understand the primary consensus attributes with IVP studies. Later, it might be reasonable to have an expert panel to develop the consensus language.

The IVP approach allows the assessor to employ their own attributes and thus overcomes the need for assessors to interpret the complex means of consensus attributes used in CVP. For example, the attribute clarity can have several definitions and it cannot be ensured that all assessors would understand and agree upon the meaning and usage of a such an attribute scale. The results of individual vocabulary development studies can give a lot of detailed information of the perception of acoustics, in addition to the method being relatively rapid to implement. The discriminating attributes elicited by the assessors provide valuable information as such, but the ordering of samples with these attributes in a common factorial space enables us to create sensory profiles of the studied concert halls.

The process of sensory evaluation with individually elicited attributes.

Usually, the process lasts 3-4 times 2h for each assessor.

Classification of measurement methods in the physical, sensory and affective domains, as presented by Lorho [1].

‹ ›

Research on sensory evaluation in Aalto

We have used sensory evaluation for concert hall acoustics studies. The main results are presented on separate pages, see more...

References

{bibtex}virtualacoustics/sensory_ivp_page.bib{/bibtex}