Abstract: A tire noise reduction device and a pneumatic tire, in which tire vibration can be reduced while durability is maintained and tire noise is reduced. The tire noise reduction device includes two main sound absorbing members for changing the cross-sectional area of a cavity of a tire in the circumferential direction of the tire and two assistant sound absorbing members disposed between the two main sound absorbing members. Each of the sound absorbing members is formed of a porous material. Each main sound absorbing member includes a first sound absorbing part and a second sound absorbing part, where the second sound absorbing part has a density lower than that of the first sound absorbing part. Each assistant sound absorbing member has a density higher than that of the second sound absorbing part and a thickness less than that of the main sound absorbing member.

Abstract: There is provided a tire noise reduction device and a pneumatic tire, in which tire vibration can be reduced while durability is maintained and tire noise is further reduced. The tire noise reduction device 1 of the present invention includes two main sound absorbing members 3 for changing the cross-sectional area of a cavity 15 of a tire in the circumferential direction of the tire and two assistant sound absorbing members 4 disposed between the two main sound absorbing members 3. Each of the sound absorbing members 3 and 4 is formed of a porous material. Each main sound absorbing member 3 comprises a first sound absorbing part 3A located on a tread portion inner surface 11a side thereof and a second sound absorbing part 3B located on a side thereof away from the tread portion inner surface 11a. The second sound absorbing part 3B has a density lower than that of the first sound absorbing part 3A.

Abstract: Disclosed is a tire noise reduction device to be mounted on the inner surface of the tread portion of a pneumatic tire facing its cavity. The tire noise reduction device includes an annular fixing elastic band and sound absorbing members disposed on the inner surface of the tread portion opposite to each other at two locations around its circumference by the fixing elastic band. The fixing elastic band has an outer peripheral length L defined in a certain range in relationship with the mass Wa of the sound absorbing members, the total mass We of the tire noise reduction device, and the inner peripheral length Li of the tire.