5 results about "Mid-frequency" patented technology

This invention provides a multi-layered lightweight sound-absorbing and insulating material, comprising a layer of sound-absorbing cotton, a cup-shaped plastic film layer, and a plastic board layer stacked together. Multiple cup-shaped structures are arranged in an array on the cup-shaped plastic film layer. Each cup-shaped structure has a second through-hole at its bottom, and these structures are arranged periodically according to the size of the second through-hole. Within each arrangement cycle, there are multiple second through-holes with different diameters. The cup-shaped structures corresponding to the different diameters of the second through-holes form multiple Helmholtz resonators with different resonance frequencies. This invention forms multiple Helmholtz resonators with different resonance frequencies through multiple cup-shaped structures with different through-hole diameters. The coupling effect of the perforated cup-shaped structures with different resonance frequencies generates a continuous and wide mid-to-low frequency resonant sound-absorbing band. While possessing a certain high-frequency sound absorption capability, it significantly improves the low-to-mid frequency sound absorption and insulation capability. Compared with traditional porous sound-absorbing materials such as felt fibers and sound-absorbing cotton, it greatly improves the sound absorption and insulation capability at the same thickness.

A circuit tuning radio frequency (RF) power. The circuit includes a low to mid frequency (LF / HF) tuning circuit including a variable LF / MF capacitor coupled in series with an LF / MF inductor. The LF / MF tuning circuit is coupled between ground and a common node configured to receive an RF input. The circuit includes a high frequency (HF) tuning circuit coupled in parallel to the LF / MF tuning circuit between ground and the common node. The HF tuning circuit includes a variable HF capacitor coupled in series with an HF inductor. Cross parallel isolation occurs between the LF / MF inductor of the LF / MF tuning circuit and the HF inductor of the HF tuning circuit when adjusting the variable LF / MF capacitor or variable HF capacitor.

Acoustic output device, comprehensive: a bone conduction loudspeaker configured to generate bone conduction sound waves; an air conduction loudspeaker comprising a diaphragm, wherein the air conduction loudspeaker is configured to generate air conduction sound waves by vibrating the diaphragm, where the air conduction loudspeaker is independent of the bone conduction loudspeaker; at least one enclosure configured to house the bone conduction loudspeaker and the air conduction loudspeaker; where the angle between the direction of vibration of the bone conduction loudspeaker and the direction of vibration of the center of the diaphragm of the air conduction loudspeaker is 70° to 115°, Bone conduction sound waves have medium to high frequencies, while air conduction sound waves have low to medium frequencies.

A speaker system mounted in a vehicle has a low frequency speaker and a mid frequency speaker disposed above the low frequency speaker in a vertical axis, which reduces the case where the position of the sound image of the mid frequency sound is shifted downward. A speaker system (1A) has a low frequency speaker (WF), a mid frequency speaker (SC), a filter (111), and a filter (112). The low frequency speaker (WF) and the mid frequency speaker (SC) are disposed in front doors of a vehicle. The mid frequency speaker (SC) is disposed at a position above the low frequency speaker (WF) in a vertical axis in a vertical direction. The filter (111) is a low pass filter disposed between an output terminal (20) of an amplifying device (2) and the low frequency speaker (WF). The filter (112) is a high pass filter disposed between the output terminal (20) and the mid frequency speaker (SC). A cross-over frequency between a frequency response of an output system (L1) including the filter (111) and the low frequency speaker (WF) and a frequency response of an output system (L2) including the filter (112) and the mid frequency speaker (SC) is 300 Hz or less.

This invention discloses a mid-to-low frequency hybrid broadband sound absorber, comprising: a first Helmholtz resonator with a first absorption peak frequency band; a second Helmholtz resonator with a second absorption peak frequency band; the second absorption peak frequency band being higher than the first absorption peak frequency band; and a plurality of discrete porous material blocks; the first and second Helmholtz resonators are spatially separated by at least one of the plurality of porous material blocks. This invention achieves effective extension of low-frequency sound absorption to mid-frequency; it achieves effective connection and fusion of optimized mid-to-high frequency sound absorption bands with extended low-to-mid frequency sound absorption bands; the sound absorber of this invention forms continuous, flat, and efficient broadband sound absorption performance within the target frequency band. Simulation verification shows that the average sound absorption coefficient in the 400Hz-2000Hz frequency band can exceed 0.8.