Shepard Tone Engine Sound Synthesis for Continuous EV RPM Feedback
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Solution Overview
Problem
Existing engine sound enhancement systems for electric vehicles fail to provide responsive feedback to continuous RPM changes, leading to unpleasant sounds at high speeds, as they lack dynamic adjustment based on vehicle conditions and motor types.
Innovation Solution
A system and method utilizing a Shepard tone generator, which modifies tone parameters in response to vehicle operational data signals like RPM, throttle position, and acceleration, to create a continuously varying engine sound that simulates gear changes without conscious perception, using audio transducers for reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engine sound is directly connected to very high RPM of electric motor, then the sound responds accurately to motor speed, but the sound becomes unpleasant and wears on the driver when sustained at high speed
Solution Approach 1:
The system dynamically changes acoustic parameters (frequency, amplitude, spectral content) of the synthesized engine sound based on RPM range. At different RPM levels, different parameter sets are applied to maintain pleasant auditory characteristics while preserving the connection between sound and motor speed. This resolves the contradiction by transforming the sound parameters rather than the physical connection.
Solution Approach 2:
The engine sound synthesis system continuously adapts its output characteristics in real-time based on instantaneous RPM values. The system transitions between different sound generation modes and parameter configurations as RPM changes, creating a dynamic response that maintains both accuracy and comfort across the entire operating range.
2Object-affected harmful factors
If engine sound is geared down to sound pleasing, then driver comfort is improved, but the direct relationship between motor RPM and sound frequency is lost
Solution Approach 1:
The system uses RPM sensor feedback to continuously adjust the synthesized sound parameters. The RPM value serves as a control input that determines the frequency, amplitude, and spectral characteristics of the generated sound. This feedback mechanism preserves the informational relationship between motor speed and sound while allowing the sound to be shaped for comfort.
Solution Approach 2:
A signal processing intermediary (the sound synthesis algorithm) is introduced between the RPM sensor and the audio output. This intermediary transforms the raw RPM data into pleasant sound waves while maintaining the functional relationship, acting as a mediator that reconciles the conflicting requirements of comfort and information preservation.
3Device complexity
If traditional engine sound enhancement systems are used, then simple sound generation is achieved, but they lack dynamic adjustment capability for continuous RPM changes in electric motors
Solution Approach 1:
The system implements dynamic parameter adjustment where sound generation characteristics change continuously with RPM. Unlike static traditional systems, this system adapts its output in real-time, switching between different synthesis modes and parameter sets to match the continuous variable nature of electric motor operation.
Solution Approach 2:
The system changes multiple acoustic parameters (frequency, amplitude, spectral distribution, timbre) based on RPM input. This multi-parameter adjustment capability enables the system to respond appropriately to continuous RPM changes while maintaining a relatively simple overall architecture based on digital signal processing.
Data Source
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AI summary
A system and method for synthesizing an engine sound may receive one or more vehicle operational data signals. One or more tone parameters associated with a Shepard tone generator may be modified responsive to the one or more vehicle operation data signals. A Shepard tone may be generated responsive to the modified one or more tone parameters. The Shepard tone may be reproduced using one or more audio transducers.