# Using Virtual Soundwalk Approach for Assessing Sound Art Soundscape Interventions in Public Spaces
## Materials and Methods
### Experiment in the Auralisation Laboratory  
#### 2.3.1 Advantages of the Research in Laboratory Conditions Instead of the Soundwalk In Situ  
The two most common soundscape analysis methods are based on soundwalks or laboratory experiments via listening tests backed up with questionnaires, semantic scales, behavioral observation protocols, or interview protocols [26]. Both approaches are considered reliable for soundscape assessment [53; 54]. For this study laboratory experiments were chosen while attaining some of the beneficial characteristics of the soundwalk approach. Laboratory conditions allow for critical listening as opposed to selective listening [76]. However, [PERSON] and [PERSON] [77] point out the deficiencies of the laboratory approach because of the difficulty in simulating complex spatial relationships between sound sources and listener, and the interrelationship between micro-climate and socio-cultural factors. Tests in situ, based on the soundwalk method, automatically take into account those factors as well as meteorological conditions, which can distort the results when compared to the research in laboratory conditions. On the other side, [PERSON] et al. [56] found high correlations in sound source recognition and soundscape assessments between laboratory soundscape research featuring different sound reproduction techniques and on-site surveys. In this study the impact of the overall environment in which the analyzed acoustic environment was recorded  
Figure 4: The percentage of the picture showing foliage as follows: A1 25.2%, A2 11.7%, B1 20.0%, B2 39%, C1 70.9%, C2 27.6%. was taken into account, in particular: (1) spatial interrelationships of sound sources (including their movement)--by recording using the FOA microphone, (2) meteorological conditions--by running the recording sessions in as similar (and moderate) weather conditions as possible, (3) socio-cultural factors--by controlling the socio-cultural structure of the group of respondents, (4) the interrelationship between the acoustic and visual experience--by including the recorded visual material in the test. On the other hand, testing in situ inevitably prevents a precise comparison of key/selected measurement points, due to the large number of external factors which the respondents experience while passing from one measurement point to another and the inability for each participant to experience the exact distance and orientation to the sound sources in question [53]. Benefits of tests in laboratory conditions that contribute to the comparison (of different soundscapes) are:  
1. accurate, efficient, and fast exchange between multiple sound environments (recorded at geographically considerable distances);
2. repeatable conditions for listening to multiple locations;
3. repeatable conditions for multiple participants for the same recorded location/acoustic environment. The laboratory approach was chosen so that the same group of participants could (easily) assess urban open spaces located in different cities, while spatial relation between the listener and analyzed sound sources was preserved. As the same group of participants remained unchanged across the locations, the impact of socio-cultural factors (i.e., translation of the questionnaire since chosen locations are in different countries) was minimized. Furthermore, per ISO/TS 12913-3:2018, the upper limit of the participants number per soundwalk is suggested to be around 20 people as it is considered that a higher number will start to significantly influence the assessment results by reducing calmness and increasing the perceived eventfulness as the participants on their own will start to be perceived as a crowd [29]. The virtual soundwalk approach was used since it was considered that retaining an insight into spatial relations within a spatial sequence provides results vital for possible application in design.