Abstract: In order to study the sound absorbing properties of activated carbon fiber, viscose-based activated carbon fiber felt with different specifications are prepared in the same condition, and the sound absorbing properties of porous materials are tested by employing the transfer function method in the 250-1600Hz middle and low frequencies acoustic range. Thereafter, the impact of such parameters as specific surface area, thickness, density and thickness of airspace on back on sound absorbing properties is analyzed. The result shows that porous materials like activated carbon fiber felt have better sound absorbing properties, sound absorbing properties in middle frequency are superior to those in low frequency; moreover, as specific surface area, thickness, density and thickness of airspace on back increase, sound absorbing properties improve ,but the average sound absorbing coefficient show different degrees of increase. The research can serve as reference for enterprises when developing sound absorbing materials like activated carbon fiber.

Key words: activated carbon fiber, sound absorbing coefficient, specific surface area, thickness, surface density, depty of cavity