Volume-Dependent Loudspeaker Equalization for Frequency Drop-Offs
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Solution Overview
Problem
Loudspeaker systems often exhibit low frequency and high frequency drop-offs in their frequency transfer function, leading to deficiencies in sound reproduction, particularly at intermediate frequencies, which existing technologies have not adequately addressed.
Innovation Solution
A loudspeaker system comprising an input unit, an equalization unit that applies specific frequency-dependent gain functions based on volume settings, and a loudspeaker unit, which operates in two modes (full bandwidth and limited bandwidth) to adapt equalization according to the connected audio interface, using digital filters and filter coefficients to compensate for frequency deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed dedicated 'extra gain' is applied at low frequencies to compensate for frequency drop-off, then low frequency reproduction is improved, but the system lacks adaptability to different volume levels and operating conditions
Solution Approach 1:
The patent implements dynamic equalization by making the equalization function variable based on volume control settings. Instead of a fixed equalization curve, the system selects from multiple predefined equalization functions (EQ0, EQ1, ..., EQN) corresponding to different volume steps (V0, V1, ..., VN). This allows the equalization to adapt dynamically to the current operating volume level, resolving the contradiction between maintaining reliable sound reproduction and adapting to different volume conditions.
Solution Approach 2:
The system changes the equalization parameters (frequency dependent gain values) based on the volume control setting. Each volume step is associated with a specific equalization function that has optimized frequency dependent gain values for that particular volume level. This parameter adaptation allows the system to maintain optimal sound reproduction quality across different volume levels and operating conditions.
2Adaptability or versatility
If multiple predefined equalization functions are applied for different volume steps, then adaptability to volume levels is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing multiple equalization functions (EQ0, EQ1, ..., EQN) that are optimized for different volume steps. Instead of computing complex equalization in real-time based on volume changes, the system prepares these equalization functions in advance and simply selects the appropriate one based on the current volume setting. This reduces the real-time computational complexity while maintaining high adaptability.
Solution Approach 2:
The system manages complexity by organizing equalization parameters into discrete, predefined sets corresponding to different volume steps. Each equalization function contains frequency dependent gain values that are optimized for its associated volume level. This structured parameter organization allows the system to achieve high adaptability through simple parameter selection rather than complex real-time calculations.
3Reliability
If the system operates in full bandwidth mode for music reproduction, then sound quality is improved, but power consumption increases under power constraints
Solution Approach 1:
The patent implements dynamic mode switching that adapts the equalization bandwidth to the current operating conditions. The system can operate in full bandwidth mode when high sound quality is required (such as music playback) and switch to limited bandwidth mode when power conservation is prioritized. This dynamic adaptation allows the system to optimize the balance between sound reproduction quality and power consumption based on the current application and available power resources.
Data Source
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AI summary
The application relates to a loudspeaker system comprising a) an input unit providing an electric input audio signal; b) an equalization unit for modifying said electric input audio signal or a processed version thereof in dependence on frequency and to provide an equalized electric audio signal according to a predefined equalization function, c) a loudspeaker unit for converting said equalized electric audio signal or a processed version thereof to an acoustic output sound signal, and d) a user interface for modifying a volume level of said output sound signal in a multitude (N) of steps V0, V1, ..., VN, each predefined specific equalization function EQ0, EQ1, ..., EQN indicates a predefined frequency dependent gain to be applied to the audio signal when a corresponding volume V0, V1, ..., VN is selected, the loudspeaker system is configured to operate in at least two modes of operation, a first mode operating in a full bandwidth mode and a second mode operating in a limited bandwidth mode, and the loudspeaker system is further configured to automatically switch between operating in the first mode or the second mode depending on the monitored connected interface.