**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**5

# air viscosity Related Publications

##### 5 Optimization of Loudspeaker Part Design Parameters by Air Viscosity Damping Effect

**Authors:**
Manabu Sasajima,
Yue Hu,
Takao Yamaguchi,
Xilu Zhao,
Yoshio Koike,
Akira Hara

**Abstract:**

This study optimized the design parameters of a cone loudspeaker as an example of high flexibility of the product design. We developed an acoustic analysis software program that considers the impact of damping caused by air viscosity. In sound reproduction, it is difficult to optimize each parameter of the loudspeaker design. To overcome the limitation of the design problem in practice, this study presents an acoustic analysis algorithm to optimize the design parameters of the loudspeaker. The material character of cone paper and the loudspeaker edge were the design parameters, and the vibration displacement of the cone paper was the objective function. The results of the analysis showed that the design had high accuracy as compared to the predicted value. These results suggested that although the parameter design is difficult, with experience and intuition, the design can be performed easily using the optimized design found with the acoustic analysis software.

**Keywords:**
Optimization,
Design Parameters,
air viscosity,
loudspeaker

##### 4 Acoustic Finite Element Analysis of a Slit Model with Consideration of Air Viscosity

**Authors:**
M. Sasajima,
Y. Koike,
M. Watanabe,
T. Yamaguchi Y. Kurosawa

**Abstract:**

In very narrow pathways, the speed of sound propagation and the phase of sound waves change due to the air viscosity. We have developed a new finite element method (FEM) that includes the effects of air viscosity for modeling a narrow sound pathway. This method is developed as an extension of the existing FEM for porous sound-absorbing materials. The numerical calculation results for several three-dimensional slit models using the proposed FEM are validated against existing calculation methods.

**Keywords:**
Simulation,
FEM,
air viscosity,
slit

##### 3 Examination of the Effect of Air Viscosity on Narrow Acoustic Tubes Using FEM Involving Complex Effective Density and Complex Bulk Modulus

**Authors:**
T. Yamaguchi,
M. Sasajima,
Y. Koike,
Y. Kurosawa,
M. Watanabe

**Abstract:**

Earphones and headphones, which are compact electro-acoustic transducers, tend to have a lot of acoustic absorption materials and porous materials known as dampers, which often have a large number of extremely small holes and narrow slits to inhibit the resonance of the vibrating system, because the air viscosity significantly affects the acoustic characteristics in such acoustic paths. In order to perform simulations using the finite element method (FEM), it is necessary to be aware of material characteristics such as the impedance and propagation constants of sound absorbing materials and porous materials. The transfer function is widely known as a measurement method for an acoustic tube with such physical properties, but literature describing the measurements at the upper limits of the audible range is yet to be found. The acoustic tube, which is a measurement instrument, must be made narrow, and the distance between the two sets of microphones must be shortened in order to take measurements of acoustic characteristics at higher frequencies. When such a tube is made narrow, however, the characteristic impedance has been observed to become lower than the impedance of air. This paper considers the cause of this phenomenon to be the effect of the air viscosity and describes an FEM analysis of an acoustic tube considering air viscosity to compare to the theoretical formula by including the effect of air viscosity in the theoretical formula for an acoustic tube.

**Keywords:**
Porous Materials,
FEM,
air viscosity,
acoustic tube,
earphones,
transfer function method,
sound absorbing materials

##### 2 Acoustic Analysis with Consideration of Damping Effects of Air Viscosity in Sound Pathway

**Authors:**
T. Yamaguchi,
M. Sasajima,
Y. Koike,
Y. Kurosawa,
M. Watanabe

**Abstract:**

**Keywords:**
Simulation,
Damping,
FEM,
air viscosity

##### 1 Theoretical Analysis of Damping Due to Air Viscosity in Narrow Acoustic Tubes

**Authors:**
T. Yamaguchi,
M. Sasajima,
Y. Koike,
Y. Kurosawa,
M. Watanabe

**Abstract:**

**Keywords:**
FEM,
air viscosity,
porous material,
acoustic tube,
earphones,
sound-absorbing material,
transfer function method