Insertion loss of a thin partition for audio sounds generated by a parametric array loudspeaker

Area of Science:

• Acoustics
• Signal Processing
• Materials Science

Background:

• Parametric array loudspeakers (PALS) generate highly directional sound.
• The directivity of PALS is known to degrade when encountering obstacles.
• Understanding this degradation is crucial for applications involving sound transmission through barriers.

Purpose of the Study:

• To investigate the phenomenon of directivity deterioration in PALS after sound transmission through thin partitions.
• To compare the transmission characteristics of PALS with traditional sound sources through barriers.

Main Methods:

• Utilized a parametric array loudspeaker (PAL) radiation model based on the Westervelt equation.
• Employed the plane wave expansion method for sound field calculations.
• Simulated sound fields behind aluminum foil and porous material using quasi-linear and paraxial approximations for ultrasonic waves.
• Conducted comparative analysis with point monopole and traditional directional sound sources.

Main Results:

• Simulations and experiments demonstrated a significant reduction in transmitted sound from PALS behind thin partitions.
• The focused radiation axis of PALS was found to be less pronounced after transmission.
• Thin partitions effectively blocked the ultrasonic components responsible for PAL directivity.
• Traditional audio sources showed minimal impact from the partitions.

Conclusions:

• Thin partitions severely impede the directivity of parametric array loudspeakers by blocking essential ultrasonic frequencies.
• PALS are less suitable for applications requiring sound transmission through thin barriers compared to traditional audio sources.
• The study provides valuable insights into the acoustic behavior of PALS in complex environments.