Engine Sound Enhancement Using Variable-Rate Waveforms
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Solution Overview
Problem
Existing engine sound enhancement systems require significant processing resources to synthesize a large number of harmonic orders of a fundamental sine wave, which is inefficient and resource-intensive.
Innovation Solution
Generating and synthesizing a small number of waveforms, each defined by a playback rate and modified by pulse variations, derived from engine RPM signals and tailored to vehicle properties, to create an engine sound enhancement output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large number of harmonic orders are synthesized to generate desired engine sound, then the engine sound quality is improved, but the processing resources required increase significantly
Solution Approach 1:
The patent segments the complex task of generating engine sound harmonics into a small number of carefully designed waveforms (typically 3-5 waveforms) that capture the essential harmonic content. Each waveform is assigned a specific playback rate corresponding to different harmonic orders, allowing the system to reproduce engine sound characteristics without synthesizing all 65 harmonic orders individually. This segmentation reduces processing complexity while maintaining sound quality.
Solution Approach 2:
The patent changes the playback rate parameter of a small set of waveforms dynamically based on engine RPM and selected harmonic orders. By varying the playback rate rather than generating multiple fixed harmonic waveforms, the system achieves flexible engine sound reproduction with reduced processing requirements. The playback rate is calculated as a function of engine RPM and the desired harmonic order, allowing real-time adaptation without complex synthesis.
2Reliability
If multiple waveforms with different playback rates are generated to enhance engine sound, then the engine sound enhancement effectiveness is improved, but the computational complexity increases
Solution Approach 1:
The patent implements dynamic waveform generation where the playback rate of each waveform is continuously adjusted based on engine RPM and the selected harmonic order. This dynamic approach allows the system to maintain accurate engine sound reproduction across varying operating conditions without requiring a large fixed set of waveforms. The system dynamically selects and adjusts a small number of waveforms rather than processing multiple static harmonic waveforms simultaneously.
Solution Approach 2:
The patent pre-calculates and stores waveform parameters (amplitude, duration, playback rate relationships) for different harmonic orders during system initialization or tuning phases. This preliminary preparation allows the real-time system to simply retrieve and play back pre-configured waveforms with adjusted playback rates, rather than performing complex harmonic synthesis calculations during engine operation. The computationally intensive work is done in advance, not during runtime.
3Productivity
If a small number of waveforms are used to reduce processing requirements, then the processing efficiency is improved, but the engine sound quality may be compromised
Solution Approach 1:
The patent extracts and isolates the most critical waveform parameters (amplitude, duration, playback rate relationships) that define engine sound characteristics. By identifying and extracting only these essential parameters rather than synthesizing complete harmonic waveforms, the system achieves efficient processing with minimal waveforms. The extraction focuses on the fundamental parameters that most significantly impact perceived engine sound quality.
Solution Approach 2:
Each waveform in the patent serves multiple functions: it can represent different harmonic orders when played at different rates, can be adjusted in amplitude to emphasize or de-emphasize specific frequency ranges, and can be combined with other waveforms to create composite engine sounds. This multi-functionality allows a small set of waveforms to replace what would traditionally require many specialized harmonic waveforms, maintaining sound quality while improving processing efficiency.
Data Source
AI summary
An ESE system is provided. The ESE system includes a controller. The controller is configured to receive an RPM signal from an engine control unit ECU. The controller is further configured to calculate a reference frequency of engine vibrations based on the RPM signal. The controller is further configured to generate one or more waveforms. Each of the one or more waveforms has a playback rate based on the reference frequency. A first waveform of the one or more waveforms includes a first pulse modified by a first pulse variation. The controller is further configured to generate an ESE output signal based on the one or more waveforms. The controller is further configured to provide the ESE output signal to an audio output system.