Update README.md

README.md

@@ -51,3 +51,23 @@ The audio clips were selected from the **CC0-licensed subset of FSD50K**.
 The onomatopoeic images were created by 18 illustrators recruited through the 99designs platform.
 Each illustrator listened to 50 sound event clips and created one onomatopoeic image for each sound event class.
 
+## License
+
+MIAO contains audio files and image files with different licensing terms.
+
+### Audio files
+
+The audio files are drawn from the CC0-licensed subset of FSD50K and are distributed under the same **CC0-1.0 license**.
+
+### Image files
+
+The onomatopoeic image files are available under the following terms:
+
+- **Research use:** The image files may be used under the **MIT License** for research purposes.
+- **Commercial use:** Commercial use of the image files requires a separate paid license.
+
+For commercial use of the image files, please contact:
+
+```text
+Keisuke Imoto
+keisuke.imoto (at_mark) ieee.org