Active noise control using bass management and a method for an automatic equalization of sound pressure levels

US8396225B2 · kind B2 · utility

Assignee

• HARMAN BECKER AUTOMOTIVE SYSTEMS GMBH · DE

Inventors

• Markus Christoph · Straubing, DE
• Leander Scholz · Salching, DE

Key dates

• Filing date: Sep 29, 2008
• Grant date: Mar 12, 2013
• Expiry date: Sep 22, 2031

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04R2499/13
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

A method for an automatic equalization of sound pressure levels in at least one listening location, where the sound pressure is generated by a first and at least a second loudspeaker, comprising supplying an audio signal of a programmable frequency to each loudspeaker, where the audio signal supplied to the second loudspeaker is phase-shifted by a programmable phase shift relative to the audio signal supplied to the first loudspeaker, and where the phase shifts of the audio signals supplied to the other loudspeakers thereby are initially zero or constant; measuring the sound pressure level at each listening location for different phase shifts and for different frequencies; providing a cost function dependent on the sound pressure level; and searching a frequency dependent optimal phase shift that yields an extremum of the cost function, thus obtaining a phase function representing the optimal phase shift as a function of frequency.