NobleMinds Montessori - DID YOU KNOW THAT? This Montessori material (Sound box) helps a child refine his or her auditory senses in a controlled and engaging way. The material 'isolates one difficulty'
Montessori In A Minute: Sound Cylinders
Sound Boxes Polished – Montessori Materials, Learning Toys and Furniture India
Sound Boxes - ETC Montessori Online
Amazon.com: Elite Montessori Sound Boxes : Toys & Games