Volume-responsive loudness compensation circuits, systems, and methods

• US 6,965,676 B1
• Filed: 06/27/2000
• Issued: 11/15/2005
• Est. Priority Date: 10/19/1999
• Status: Active Grant

• Current Assignee: UD Technology Corporation
• Original Assignee: Texas Instruments, Inc.
• Inventors: Allred, Rustin W
• Primary Examiner(s): Mei, Xu
• Assistant Examiner(s): CHAU, COREY P
• Application Number:
  US09/603,950
• Time in Patent Office: 1,967 Days
• Field of Search: 381/107, 381/109, 381/104, 381/102, 381/105, 381/108
• US Class Current: 381/104
• CPC Class Codes: H03G 5/005 of digital signals

Abstract

An audio compensation system (20) for producing a sound compensated output signal (S_o). The system comprises a volume control circuit (24) for producing a volume-adjusted signal (S_ic) by applying a volume adjustment to an audio signal in response to a volume setting, wherein the sound compensated output signal is responsive to the volume-adjusted signal. The system also comprises circuitry (26, 30, 32) for producing an amplified signal (S_ifa) by amplifying a selected bandwith of signals in response to the volume setting. The sound compensated output signal is also responsive to the amplified signal.

Claims

1. An audio compensation system for producing a sound compensated output signal, comprising:

a volume control circuit for producing a volume-adjusted signal by applying a volume adjustment to an audio signal in response to a volume setting, wherein the sound compensated output signal is responsive to the volume-adjusted signal; and

circuitry for producing an amplified signal by amplifying a selected bandwith of signals in response to the volume setting, wherein the sound compensated output signal is also responsive to the amplified signal, wherein the circuitry for producing an amplified signal comprises;

a logarithm estimating circuit for receiving a value in response to the volume setting and outputting a first estimated signal;

circuitry for modifying the first estimated signal to form a modified signal; and

an inverse logarithm estimating circuit for receiving the modified signal and outputting a second estimated signal,

wherein;

the sound compensation output signal is responsive to the second estimated signal, wherein the logarithm estimating circuit is a base 2 logarithm estimating circuit;

the inverse logarithm estimating circuit is a base 2 inverse logarithm estimating circuit, wherein the circuitry for modifying the first estimated signal comprises circuitry for modifying the first estimated signal according to a linear modification; and

the linear modification is in response to an adjustable slope value and an adjustable offset value.

2. An audio compensation system for producing a sound compensated output signal, comprising:

a volume control circuit for producing a volume-adjusted signal by applying a volume adjustment to an audio signal in response to a volume setting, wherein the sound compensated output signal is responsive to the volume-adjusted signal; and

circuitry for producing an amplified signal by amplifying a selected bandwith of signals in response to the volume setting, wherein the sound compensated output signal is also responsive to the amplified signal, wherein the circuitry for producing an amplified signal comprises;

a logarithm estimating circuit for receiving a value in response to the volume setting and outputting a first estimated signal;

circuitry for modifying the first estimated signal to form a modified signal; and

an inverse logarithm estimating circuit for receiving the modified signal and outputting a second estimated signal,

wherein;

the sound compensation output signal is responsive to the second estimated signal,

the circuitry for modifying the first estimated signal comprises circuitry for modifying the first estimated signal according to a linear modification, and

the linear modification is in response to an adjustable slope value and an adjustable offset value.

3. A method of operating an audio compensation system to produce a sound compensated output signal, comprising the steps of:

applying a volume adjustment to an audio signal in response to a volume setting from, a volume control circuit to produce a volume-adjusted signal, wherein the sound compensated output signal is responsive to the volume-adjusted signal; and

producing an amplified signal by amplifying a selected bandwith of signals in response to the volume setting, wherein the sound compensated output signal is also responsive to the amplified signal, wherein the producing step comprises;

receiving a value in response to the volume setting and forming an estimated logarithm signal;

modifying the estimated logarithm signal to form a modified signal; and

receiving the modified signal and forming an inverse logarithm estimated signal,

wherein;

the sound compensation output signal is responsive to the inverse logarithm estimated signal,

the modifying step comprises modifying the estimated logarithm signal according to a linear modification, and the linear modification is in response to an adjustable slope value and an adjustable offset value.