A note on the audio sound power generated by a parametric array loudspeaker

Area of Science:

• Acoustics and Audio Engineering
• Nonlinear Acoustics
• Loudspeaker Technology

Background:

• Parametric array loudspeakers (PALs) present unique challenges in characterizing sound power due to inherent nonlinear acoustic processes.
• Accurate measurement and modeling of sound power are crucial for understanding and optimizing PAL performance.

Purpose of the Study:

• To investigate and model the sound power characteristics of parametric array loudspeakers (PALs).
• To determine the relationship between audio sound power, audio frequency, aperture size, and ultrasound frequency in PALs.
• To quantify the energy conversion efficiency from ultrasound to audio sound in typical PAL configurations.

Main Methods:

• Utilized the spherical convolution directivity model to calculate far-field sound intensity.
• Derived sound power from the calculated far-field intensity.
• Analyzed the proportionality of audio sound power with key parameters like frequency and aperture size.

Main Results:

• Audio sound power is approximately proportional to the square of the audio frequency.
• Audio sound power is also approximately proportional to the square of the aperture size.
• Audio sound power shows an inverse relationship with the ultrasound frequency.
• The conversion efficiency from ultrasound to audio sound is typically below 0.15% for common PAL setups.

Conclusions:

• The spherical convolution directivity model provides a viable method for characterizing PAL sound power.
• The identified relationships offer insights into optimizing PAL design for desired audio output.
• The low conversion efficiency highlights areas for potential improvement in PAL technology.