Digital Rotary Speaker Emulation With Phase-Controlled Sound Changes

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Solution Overview

Problem

Existing musical instruments struggle to simulate the sound characteristics of a rotary speaker without the mechanical limitations of a physically rotating speaker, limiting the creative possibilities of musical performance.

Innovation Solution

A sound signal conversion device that applies periodic changes to an input sound signal, determining the phase of these changes based on initial and reset phase information to simulate rotary speaker sounds without mechanical rotation, allowing for unconventional sound characteristics and player control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical rotary speaker is used to simulate rotary speaker sound, then the sound characteristics can be reproduced, but mechanical restrictions and physical limitations are introduced

Engineering Contradiction:
Improvesound characteristic reproductionVSAvoidmechanical structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical rotary speaker system with a digital signal processing system. Instead of physically rotating speakers to create the rotary speaker effect, the invention uses a sound signal conversion device that processes audio signals through digital algorithms to simulate the same sound characteristics without any mechanical moving parts.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a virtual copy of the rotary speaker effect through digital signal processing. The sound signal conversion device analyzes and reproduces the characteristic sound patterns of a mechanical rotary speaker using software algorithms, thereby copying the essential auditory properties without replicating the complex mechanical structure.

Inventive Principle:
Principle #26Copying

2Adaptability or versatility

If a mechanical rotary speaker is used, then rotary speaker sound effects are achieved, but mechanical restrictions limit creative possibilities

Engineering Contradiction:
Improvecreative possibilitiesVSAvoidmechanical operation constraints
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent implements dynamic control of the rotary speaker effect through digital signal processing parameters. Instead of being constrained by mechanical rotation speeds and positions, the system can dynamically adjust various parameters such as rotation speed, direction, and phase in real-time through software control, greatly enhancing creative possibilities and ease of operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent enables versatile creative control by allowing digital manipulation of multiple parameters including rotation speed, rotation direction, phase shift, and signal processing characteristics. These parameters can be changed through software without any mechanical constraints, enabling a wide range of creative possibilities that would be difficult to achieve with a physical rotary speaker.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If phase determination is not controlled, then automatic operation is simplified, but sound quality and player control are reduced

Engineering Contradiction:
Improveautomatic operationVSAvoidphase precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent incorporates feedback mechanisms that allow the system to automatically determine and adjust phase information based on the input sound signal characteristics. This feedback enables automatic operation while maintaining high phase precision, as the system continuously monitors and adjusts phase parameters to optimize sound quality reproduction.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs preliminary phase determination based on initial phase information that is established before the main signal processing begins. This preliminary action allows the system to automatically set up the correct phase relationships in advance, simplifying operation while ensuring precise phase control during subsequent signal processing.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the generation of musical sounds resembling rotary speaker outputs without mechanical constraints, offering new creative possibilities and player control over sound fluctuations.

Implementation Method 1

the high-pitch speaker is provided with a hone rotor, and the low-pitch speaker is provided with a drum rotor. The hone rotor and the drum rotor are rotated by a motor included in the rotary speaker, whereby a sound is output radially from the high-pitch and low-pitch speakers. Thus, effects such as a chorus, a vibrato and a tremolo are provided to the sound to be output from the high-pitch and low-pitch speakers due to the Doppler effect.

Methodology Applied
Scientific EffectDoppler effect: Doppler Effect

Data Source

PatentEP3839937B1Rotary speaker emulation- device, musical instrument, method and program
Publication Date: 2025.07.09 YAMAHA CORP
  • EP3839937B1 patent drawingFigure 1
  • EP3839937B1 patent drawingFigure 2
  • EP3839937B1 patent drawingFigure 3

AI summary

A sound signal conversion device includes a supplier. The supplier supplies a periodic change to an input sound signal and outputs the sound signal to which the periodic change is supplied. The supplier includes a phase determiner that determines a phase at which the periodic change supplied to the sound signal starts based on initial phase information when receiving a start instruction for starting supply of the periodic change to the sound signal.