Geometry-intermediated transport in zeolite for advanced compact loudspeaker

Abstract The linear enhancement of mechanical compliance through zeolite filling in compact loudspeakers has been theoretically and experimentally confirmed. However, utilization of this enhancement to elucidate the correlation between porous structure and acoustic properties remains elusive. This research optimizes gas diffusion ability in zeolite to enhance the acoustics performance of compact loudspeakers. Based on the mechanical compliance linear enhancement theory in zeolite-filled loudspeakers, an intrinsic parameter <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>α</mml:mi> <mml:mrow> <mml:mrow> <mml:mtext>pore</mml:mtext> </mml:mrow> </mml:mrow> <mml:mrow> <mml:mrow> <mml:mtext>ref</mml:mtext> </mml:mrow> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> is introduced to measure adsorption site accessibility. By using a hydrothermal method and etching process, ZSM-5 with varying mesostructures, including normal stacking plates, b -oriented, and radial channel plate porous configurations, are successfully synthesized. The optimal (labeled by Z5-BR) sample combines the advantages of b -oriented and radial porous structures in favor of mass transfer. At 0.3 cm 3 Z5-BR filling, the loudspeaker achieves 70 Hz resonance frequency shift Δ f 0 , 1.05 mH·cm −3 mechanical compliance enhancement slope <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>β</mml:mi> </mml:mrow> </mml:math> , and 35.79 mH·m −2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>α</mml:mi> <mml:mrow> <mml:mrow> <mml:mtext>pore</mml:mtext> </mml:mrow> </mml:mrow> <mml:mrow> <mml:mrow> <mml:mtext>ref</mml:mtext> </mml:mrow> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> , leading to a maximum 3 dB sound pressure level increase at a sound frequency of 106 Hz. This study quantitatively links the refine microstructure of porous zeolite to acoustic behavior, offering a comprehensive framework for loudspeaker material estimation and igniting the fire to design the composition and structure of acoustic materials at hundreds of Hz through microscopic diffusion-adsorption processes.