Toy for animals

A toy for animals, comprising:

• an outer, hollow shell member of elastomeric material, wherein said shell member has two generally diametrically opposed holes that are each open between the hollow interior and the exterior of said shell member;
• a single hollow, generally cylindrical flexible insert disposed within said shell member and constantly in at least partial contact therewith to keep said insert in place in said shell member and prevent free floating of said insert in said shell member, wherein said hollow insert has a first hollow volume, further wherein said insert has an integral hollow central core that extends through said first hollow volume of said insert and between at least partially flat portions of opposite ends of said hollow insert, wherein said hollow central core has a substantially circular cross-sectional configuration and forms a second hollow volume that is surrounded by said first hollow volume and is separated therefrom by material of said insert so as to form a tunnel through said insert, wherein said second hollow volume of said central core is open to the hollow interior of said shell member at said flat portions of said insert, but said second hollow volume is not open to said first hollow volume of said hollow insert, and wherein said hollow insert has a port in one of said flat portions of said insert;
• and
• an acoustic cartridge disposed in said port of said hollow insert.