4.2.1. Materials

The effectiveness evaluation was performed using two sets of color codes. We used the VIVALDI color code described in Section 3.3.1 as the baseline for our experiments. The VIVALDI color code is entirely based on sound. It uses different musical instrument timbres to express the red, orange, yellow, green, blue, and purple hues shown in Table 6. The second set is our proposed multi-sensory color code described in Section 3.3. The multisensory color code extends the VIVALDI color code by adding different scents to facilitate the identification of the saturated, light, and dark dimensions. The scent selection was performed following the cross-modal correspondence approach through a semantic differential scale survey performed with the help of the participants. The selection method is described in detail in Section 3.3.2. The scents of coffee, apple, and chocolate were selected to represent the saturated, light, and dark color dimensions, respectively. The sound color code component of the color codes was provided by reproducing pre-recorded audio tracks on a set of high-fidelity speakers at a comfortable volume level. The audio files are provided separately in the supplement materials of this work. The scent color code component was provided in bottled scent samples made available during the evaluation.
