Augmented Acoustic Instrument Feedforward Feedback Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for processing acoustic data from stringed instruments fail to achieve desired sound effects due to instability caused by feedback and uneven vibratory characteristics of the radiating structure, leading to poor sound quality and unwanted frequency superimpositions.
Innovation Solution
A feedback/feedforward control system that estimates and adjusts the transfer function between sensors and actuators in real time, incorporating feedback control to stabilize and enhance sound effects, using a device with a preamplifier, microcontroller, and digital-analog converters to process signals and control actuators for precise vibrational manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If feedforward control is used to apply digital audio effects to the radiating structure, then sound effects such as echo and reverb can be generated, but instabilities and unwanted frequency superimpositions occur due to feedback from the radiating structure
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the actual vibrations of the radiating structure and adjusts the actuator signals accordingly. The controller receives vibration signals from sensors mounted on the radiating structure and uses this feedback information to compensate for unwanted vibrations and maintain system stability while applying digital audio effects.
Solution Approach 2:
The patent measures and stores the transfer function characteristics of the radiating structure in advance. This preliminary characterization of the system's vibratory behavior allows the controller to pre-calculate compensation signals that account for the structure's resonant frequencies and mode shapes, preventing instabilities before they occur.
2Device complexity
If the radiating structure is used as a loudspeaker for transformed signals, then amplification chain is eliminated, but uneven sound quality occurs due to resonance modes inducing amplitude changes across frequencies
Solution Approach 1:
The patent applies different control signals to different regions of the radiating structure by using multiple actuators positioned at specific locations. Each actuator is controlled independently based on the local vibratory characteristics and mode shapes, allowing precise control of the sound radiation pattern and compensation for uneven frequency response across different regions of the structure.
Solution Approach 2:
The patent dynamically adjusts the actuator signals based on the detected vibratory state of the radiating structure. By continuously monitoring the structure's response and modifying the control parameters in real-time, the system compensates for resonance-induced amplitude variations and maintains uniform sound quality across different frequencies and playing conditions.
3Productivity
If actuators excite the radiating structure to produce transformed sounds, then direct acoustic radiation is achieved, but strong feedback coupling with strings occurs at certain frequencies changing resonance characteristics
Solution Approach 1:
The feedback control system detects the coupling between string vibrations and radiating structure by monitoring vibrations at multiple locations. When strong coupling is detected at certain frequencies, the controller automatically adjusts the actuator signals to compensate for the changing resonance characteristics, maintaining stable and predictable sound production.
Solution Approach 2:
The patent implements a dynamic control system that continuously adapts to changing vibratory conditions. The controller adjusts the actuator signals in real-time based on the detected coupling between strings and radiating structure, allowing the system to maintain optimal performance across varying playing conditions and frequency ranges.
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
This approach significantly reduces instabilities and enhances sound quality by accurately accounting for the vibratory characteristics of the instrument, achieving stable and targeted acoustic effects, such as echo and reverb, with improved timbre and sound level.
Implementation Method 1
a sensor ACT of the piezoelectric type
Implementation Method 2
one or more electrodynamic actuators ACT
Implementation Method 3
the radiating structure of the instrument itself (typically the CAI soundbox of a guitar for example) is used as a 'diffuser' or 'loudspeaker' of the sound signal
Data Source
Figure 1~9
Figure 3~4
Figure 5~6
AI summary
The invention relates to processing implemented by computer means of sound data output by at least one sensor and activation of at least one actuator of an acoustically radiating structure. The sensor (CAP) senses an acoustic signal output by the vibration of the radiating structure. The radiating structure bears at least one actuator (ACT) controlled by the computer means and is thus involved in the vibration of the radiating structure. In particular, the method comprises the steps of: a) measuring a transfer function of the actuator, radiating structure and sensor assembly, b) controlling activation of the actuator (ACT) so as to make the radiating structure vibrate, according to a selected setpoint: - taking account of the transfer function measured, and - taking account of the acoustic signal sensed by the sensor in feedback mode.