# City Ditty: An Inmersive Soundscape Sketchpad for Professionals of the Built Environment
## 2 Requirements Gathering, Design, and Development
### Literature Review  
While there is much research on the benefits of soundscape design in general, few studies discuss what tools are available and how they should be used at design time. [PERSON] et al. discusses the need for sound-planning tools in more detail, along with how current literature has explored the viability of using immersive tools for soundscapes [15]. The majority of previous studies focused on determining if reproductions are ecologically valid, i.e., can reproductions elicit responses and outcomes comparable to experiences in real-life environments [13; 15; 24; 25] and/or which hardware works best at reproducing this to facilitate the evaluation of soundscapes themselves [26]. For example, [PERSON] et al. [27] compared VR environments to real in-situ environments for evaluation of public spaces, while [PERSON] et al. [28] studied the quality of different sound reproduction techniques. Other work goes beyond the hardware's ability to reproduce audio-visuals by applying the concept of ecological validity [29] to soundscape reproductions to try to produce optimal lab reproductions [15; 30]. These identify further aspects by including the sample population and activities performed by the user to elicit the most accurate evaluations in a reproduction. This trend continues as a hot topic as others follow with reviews specifically on ecological validity for VR [31], and further techniques in evaluating soundscapes in VR [32]. The reproduction of soundscapes in a lab environment is highly desirable as it provides control over contextual factors such as times of day, weather conditions, and seasons, which have been shown to influence soundscape evaluations; see [PERSON] et al. [33] for a review of a wider range of contextual factors. Not only can soundscape reproduction leverage control over contextual factors, but also help identify issues that may not otherwise be apparent at design time, due to the complexity of the urban space [13]. For instance, while individual sound sources can be easily considered in isolation (e.g., traffic is loudest during rush hour), multiple sound sources combine into a larger acoustic environment that can quickly become overwhelming to keep track of. For instance, pubs are louder at night, grocery stores attract loud trucks for early morning deliveries, construction noises occur within their respective start and stop times, etc. These complex, ever-changing acoustic environments will lead to different responses and outcomes from city users, as these soundscapes can either facilitate--or disrupt--how a city user utilizes a public space or not. To capture this complexity, the Quality of the Urban Public Experience (QUPE) model accounts for the psychological, behavioural, and social responses from city users to soundscape design [1], e.g., did the soundscape foster social interactions? Did people linger to utilize local businesses? Did it promote stress reduction? Such feedback is crucial in understanding how effective a soundscape design is. Unfortunately, it is also very resource expensive to both prototype _and_ collect adequate feedback from designs in city spaces. On-site soundscape interventions require extensive collaboration between researchers, city officials, and local firms to plan and implement soundscape designs and evaluate them with public space users [1,34]. Simulations could allow for quick digital prototyping and evaluation of different options to narrow down the possibilities before physical prototypes are built. While it is not unusual for private firms and researchers to create 3D digital prototypes for consulting and soundscape evaluation, these still require very specialized skillsets and remain time consuming to build, which will act as a barrier for entry to most. For instance, [PERSON] et al. [35] created a model of Piazza Vittoria in Naples, Italy which allowed users to walk around to explore and evaluate the city soundscape in different places. However, users could not use it to make changes to the soundscape.