Engine Sound Synthesis Using Pre-computed Harmonic Parameters
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Solution Overview
Problem
Existing methods for synthesizing sound, particularly the sound of a combustion engine, require powerful digital signal processors, making them unsuitable for low-cost applications such as the automotive industry, and there is a need for an efficient method to address the lack of aural cues in hybrid and electric vehicles.
Innovation Solution
A method that analyzes sound signals by determining fundamental frequencies and harmonic model parameters, synthesizing a harmonic signal, estimating residual model parameters, and superposing the harmonic and residual signals to produce a realistic engine sound, which can be used to meet regulatory requirements for vehicle noise and provide acoustic feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If powerful digital signal processors are used for sound synthesis, then sound synthesis quality is improved, but device cost and complexity increase
Solution Approach 1:
The sound synthesis process is divided into separate functional modules: a sound effect library module that stores pre-analyzed engine sound parameters, a guide signal generation module that creates reference signals from engine operation data, and a sound synthesis module that combines these elements. This segmentation allows each module to be optimized independently and reduces the computational burden on the processor.
Solution Approach 2:
Engine sound parameters are pre-analyzed and stored in a sound effect library during offline processing. The library contains harmonic model parameters and residual model parameters that have been previously computed from actual engine recordings. During runtime, the system only needs to retrieve and combine these pre-computed parameters rather than performing complex analysis in real-time, significantly reducing processor requirements.
2Measurement precision
If complex sound analysis algorithms are used, then sound analysis accuracy is improved, but computational requirements increase
Solution Approach 1:
Instead of performing complex sound analysis algorithms during runtime, the system creates a simplified copy of the engine sound characteristics by storing key parameters (harmonic frequencies, amplitudes, phases, and residual components) in a sound effect library. These parameters are copied from offline analysis results and reused during operation, maintaining accuracy while minimizing computational energy consumption.
Solution Approach 2:
The system transforms the complex sound analysis problem into a parameter-based approach by extracting and storing specific physical parameters (fundamental frequency, harmonic frequencies, amplitudes, phases) rather than processing the entire sound waveform in real-time. This parameter transformation allows accurate sound synthesis with reduced computational requirements.
3Speed
If real-time sound synthesis is implemented, then responsiveness is improved, but processing complexity increases
Solution Approach 1:
All complex sound analysis and parameter extraction is performed in advance during offline processing, with results stored in the sound effect library. During real-time operation, the system only needs to retrieve pre-computed parameters and combine them with current guide signals, achieving fast response without real-time processing complexity.
Solution Approach 2:
The sound effect library acts as an intermediary between offline sound analysis and real-time sound synthesis. It stores pre-processed engine sound parameters and provides them to the synthesis module, decoupling the complex analysis work from the real-time synthesis operation and enabling responsive performance with simplified processing.
Data Source
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AI summary
A method for analyzing sound is described. In accordance with one example of the invention the method includes: providing an input sound signal to be analysed and determining a fundamental frequency of the input signal from the input signal or from at least one guide signal. Furthermore, the frequencies of higher harmonics of the fundamental frequency are determined, thus determining harmonic model parameters. A harmonic signal based on the harmonic model parameters is synthesized and a residual signal is estimated by subtracting the harmonic signal from the input signal. Residual model parameters are estimated based on the residual signal. Furthermore, a corresponding method for synthesizing a sound signal is described.