Dual-Mode Loudspeaker for Directional Sound Control
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Solution Overview
Problem
Conventional loudspeakers lack the ability to selectively produce sound waves in either a wide beam or a narrow beam, which can be a disturbance in public settings, as they typically emit sound in all directions without directional control.
Innovation Solution
An acoustic component that can be excited to produce sound waves in both audible and ultrasonic frequency ranges, utilizing a transducer or transducer array to modulate audio signals with ultrasonic carrier signals, creating directional beams through non-linear air interactions, allowing for both conventional and directional sound production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional loudspeakers emit sound in all directions to ensure wide coverage, then sound dissemination is maximized, but disturbance to people in public settings increases
Solution Approach 1:
The loudspeaker system dynamically switches between wide-beam and narrow-beam operating modes based on usage context. The same acoustic component can be excited at different frequency ranges to produce different beam patterns, allowing the system to adapt between maximizing sound dissemination and minimizing disturbance to surrounding people.
Solution Approach 2:
The invention changes the operating frequency parameter of the acoustic component to alter sound propagation characteristics. By exciting the component at audible frequencies, wide-beam sound is produced; by exciting at ultrasonic frequencies, narrow-beam directional sound is produced. This parameter change enables the system to resolve the contradiction between wide coverage and targeted sound delivery.
2Device complexity
If a single acoustic component is used for both audible and ultrasonic excitation, then device complexity is reduced, but the ability to produce distinct beam patterns requires sophisticated control
Solution Approach 1:
A single acoustic component is designed to perform multiple functions: it can be excited at audible frequencies to produce wide-beam sound and at ultrasonic frequencies to produce narrow-beam directional sound. This multi-functionality reduces device complexity by eliminating the need for separate loudspeakers for different beam patterns while maintaining full operational capability.
Solution Approach 2:
The control system dynamically adjusts the excitation frequency of the acoustic component based on the desired operating mode. A processor receives indications of the operating mode and generates appropriate excitation signals, automatically managing the transition between wide-beam and narrow-beam patterns without requiring manual intervention.
3Adaptability or versatility
If ultrasonic frequency excitation is used to produce directional beams, then sound directionality is improved, but the frequency range extends beyond traditional audible limits
Solution Approach 1:
The invention exploits the relationship between frequency parameter and sound propagation characteristics. By changing the excitation frequency from audible to ultrasonic ranges, the system achieves improved directionality and beam control. The same acoustic component responds differently to different frequency inputs, enabling directional sound without requiring separate hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the production of sound waves in either a wide beam or a narrow beam, addressing the issue of disturbance in public settings by allowing users to choose between conventional and directional sound modes, enhancing user control over sound dissemination.
Implementation Method 1
a piezoelectric layer; and a pair of electrodes coupled to the piezoelectric layer, the electrodes arranged to receive electrical signals so as to cause the piezoelectric layer to vibrate
Implementation Method 2
exciting the acoustic component for producing acoustic waves in the lower frequency range or in the higher frequency range
Implementation Method 3
When the vibration is in the ultrasonic frequency range, the ultrasonic signal is modulated by audio signal for creating better directivity. At this frequency range, the transducer or transducer array can produce a directional beam of ultrasonic waves. Due to the non-linear interaction of ultrasonic waves in the air, the directional beam of ultrasonic waves becomes audible after traversing a distance.
Data Source
AI summary
An apparatus uses a transducer to produce vibration in the ultrasonic frequency range and in the audible frequency range. A membrane or cantilever structure is coupled to the transducer to produce acoustic waves. When the vibration is in the audible frequency range, the membrane structure works like a conventional loudspeaker. When the vibration is in the ultrasonic frequency range, the ultrasonic signal is modulated by audio signal for creating better directivity. The acoustic waves in the ultrasonic frequency range can reproduce directional audible sound due to the nonlinear interaction of ultrasonic waves in air.