Fig 4. Results of the material categorization task.

(a) Material categorization of the sounds modified from the original metal sound (M1) using frequency coefficient l_i and damping coefficient k_i. (b) Material categorization of the sounds modified from the original drum sound (D1) using frequency coefficient l_j and damping coefficient k_j. The three numbers (CR_A, CR_B, CR_C) above each sub-figure indicate the score of the sound, i.e., the sum of the confidence rating of each category (Drum, Metal, Others) across all participants. Because only one category could be chosen for each trial, the maximal score of CR_A + CR_B + CR_C of the 19 participants was 19 × 7 = 133. Sounds along the dotted line were the sounds in which tan φ was kept the same as that of the original sound.