Minimally radiating sources for personal audio

Area of Science:

• Acoustics and Audio Engineering
• Signal Processing
• Personal Device Audio Optimization

Background:

• Minimizing audio annoyance from personal devices requires localized sound at the user while reducing levels elsewhere.
• The challenge involves minimizing radiated sound power across the far-field while maintaining user-position sound pressure levels.

Purpose of the Study:

• To analytically and experimentally investigate optimal array configurations for personal audio devices.
• To determine the trade-off between radiated noise reduction and electrical power requirements for multi-element arrays.
• To evaluate the effectiveness of two and three-element arrays in balancing performance and power consumption.

Main Methods:

• Analytical derivation of optimal two-source array directivity (hypercardioid).
• Monopole simulations to analyze linear arrays for mobile phone applications.
• Experimental validation using a small loudspeaker array under anechoic conditions.
• Investigation of coupled enclosures for improved power efficiency.

Main Results:

• The optimal two-source array achieves approximately 7 dB reduction in radiated sound power compared to a monopole.
• Two and three-element arrays demonstrate a practical compromise between noise reduction and power demands.
• Coupled enclosures for the two-source array further reduce electrical power needs.

Conclusions:

• Hypercardioid directivity is optimal for minimizing radiated sound power in personal audio applications.
• Multi-element arrays, particularly two and three-element configurations, offer effective solutions for noise reduction and power efficiency.
• Practical implementation in coupled enclosures enhances the performance of two-source arrays.