Active Sound Effect Device Velocity-Based Frequency Shifting
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Solution Overview
Problem
Conventional active sound effect generating devices in vehicles with electric motors experience a decline in realism and merchantability at high velocities due to the dominance of high-frequency sound components, leading to an uncomfortable listening experience for occupants.
Innovation Solution
An active sound effect generating device that utilizes a vehicle velocity detecting system and a frequency setting unit to exponentially increase sound frequencies with a constant multiple relationship between a lower and upper limit frequency, ensuring sound effects are generated naturally and comfortably across varying velocities, using a gain device to adjust sound levels smoothly during frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the amplitude of acoustic signals is set to increase as the degree of opening of the accelerator pedal and the virtual frequency increase, then a sense of comfort during driving operations can be obtained, but high frequency components become dominant at high velocities, making the sound effects noticeable and reducing realism
Solution Approach 1:
The patent changes the frequency parameters of the acoustic signals by introducing a frequency shifting process. A frequency shift amount is calculated based on vehicle velocity, and this shift is applied to the virtual frequency and its harmonics. This parameter change allows the system to maintain comfort-enhancing amplitude increases while shifting the dominant frequency components away from the high-frequency range that becomes noticeable to occupants at high velocities, thereby preserving realism.
2Loss of information
If sound effects are generated to increase in accordance with an increase in the vehicle velocity, then vehicle occupants can hear the sound effects corresponding to operations of the accelerator pedal, but at high velocities the narrow directivity of high frequency components makes the sound effects noticeable, impairing realism
Solution Approach 1:
The patent applies frequency shifting as a parameter change to transform the spectral characteristics of the sound effects. By calculating a frequency shift amount proportional to vehicle velocity and applying it to the acoustic signals, the system maintains the information feedback function while transforming high-frequency dominant components into lower frequency ranges that are less noticeable to occupants, thus preserving the realism of automotive running sounds.
Solution Approach 2:
The patent introduces a new dimension of frequency transformation by applying a velocity-based frequency shift. This dimensional change in the frequency domain allows the system to decouple the amplitude-velocity relationship (which provides feedback) from the frequency-noticeability relationship (which affects realism), enabling both requirements to be satisfied simultaneously through operation in an extended parameter space.
Data Source
AI summary
Sound effects are generated from a speaker inside a vehicle compartment repeatedly between a lower limit frequency and an upper limit frequency in accordance with an increase in the vehicle velocity. Consequently, the frequency is increased with respect to an increase in the vehicle velocity, in a manner so that audible sound effects, that is, sound effects at a so-called infinite scale, are generated.