Method to Improve the Audio Privacy of a Personal Smart Device


The Inventors have developed a loudspeaker design to improve audio privacy of personal smart devices, such as phones or tablets, when used in public.

Problem Addressed

Today, smart devices are ubiquitous as personal communications and entertainment devices. In most cases where the audio sound is played through the device’s speakerphone, the user has little privacy in that the sound can often be heard by bystanders. Compared to traditional audio-frequency loudspeakers that are currently employed in smart devices, parametric loudspeakers feature much better audio privacy, as the audio sound is highly directional and a private audio zone can be created. However, at present, parametric loudspeakers are only employed in outdoor applications and not portable smart devices due to their high power dissipation and subdued low frequency response. The Inventors have developed a technology that combines traditional and parametric loudspeakers to significantly reduce the device’s power dissipation while retaining the user’s privacy.


This novel amplifier/loudspeaker system combines a traditional and parametric loudspeaker. In this design, the audio input signal is first separated into two frequency bands: low frequency (<800 Hz) and high frequency (>800 Hz) by low pass filters and high pass filters respectively. The traditional loudspeaker generates the audio signal whose frequency is below the 800 Hz threshold while the parametric loudspeaker generates the audio signals above this threshold. The traditional speaker is used to generate most of the low frequency components of vowels while the parametric speaker generates higher frequency components of vowels and the full spectrum of consonants. In this way, bystanders can only hear audio sounds below a threshold frequency and the intelligibility of the overheard audio signal is significantly impaired while the user of the smart device, who is in the private audio zone, would hear the unfiltered audio spectrum.


  • Smart device user retains full audio comprehension from speaker system while gaining privacy
  • Novel loudspeaker system displays significantly reduced power dissipation over existing parametric loudspeakers