Discrete state space method and modal extension method based impact sound synthesis model

The efficient and accurate synthesis of physical parameter-controllable impact sounds is essential for sound source identification. In this study, an impact sound synthesis model of a cylinder is proposed based on discrete state space（DSS） method and modal extension method（MEM）. This model is comprised of the whole three processes of the physical interaction, i.e., the Hertz contact process, the transient structural response process, and the sound radiation process. Firstly,the modal expanded DSS equations of the contact system are constructed and the transient structural response of the cylinder is obtained. Then the impact sound of the cylinder is acquired using improved discrete Raleigh integral. Finally, the proposed model is verified by comparing with existing models. The results show that the proposed impact sound synthesis model is more accurate and efficient than the existing methods and easy to be extended to the impact sound synthesis of other structures.

Finite element study on impact sound transmission through a floating floor

To understand the characteristics of impact-sound transmission through a floor is very helpful for developing sound attenuation strategies to acquire a high quality of dwellings. Sound transmission through a floating floor to the room underneath was modeled by finite-element method (FEM). The sound pressure levels calculated by the FEM model on a scale of 1:4 was compared with the measured values, which demonstrate good agreement, particularly for impact sound of a relatively low frequency. The sound pressure level in a receiving room is strongly affected by the structural characteristics of both the floor and the room. The sound pressure transmitted through a clamped floor is lower than through a simply supported floor because of the larger rigidity of the clamped floor that contributes to the attenuation mechanism of stiffness. Increase in the thickness of the fiber-glass damping layer in the floor improves sound insulation. A larger room has a larger capacity to dissipate the sound pressure and thus has a lower sound pressure level. An asymmetric configuration of room avails sound attenuation because it has weaker structural and acoustic coupling than a symmetric one.

The admittance feature representation and impact sound feature extraction in the material identification of ribbed plates

The admittance features representing the physical attributes are used as the in termediates to extract the materialattributesrelated impact sound features of ribbed plates. Firstly, the admittance feature representations of metal ribbed plates attributes are obtained and the relationship between the admittance features and the impact sound features are established via correlation analysis method. Then, materialattributesrelated impact sound features are obtained indirectly. Finally, the performances of different sound features for the material recognition of ribbedmetal plates are verified through the Support Vector Machine classifier. The results indicate that the obtained four sets of features can effectively identify the materials of the metal ribbed plates, while the accuracy of a single feature depends on the separable degree of the corresponding material attribute. And the features extracted based on admittance functions have higher average accuracy than that of timbre features. Therefore, the proposed sound feature extraction method based on admittance features is valid, and the extracted sound features can effectively reflect the physical attributes.