Volume control for audio signals

Abstract

A motion picture soundtrack reproduction system has a center front soundtrack channel and a plurality of other soundtrack channels. A volume control adjusts the gain of all the channels. The volume control has a range of settings from a minimum to a maximum, the gain of the center front channel having substantially a first relationship to the volume control settings and the gain of the other channels having substantially a second relationship to the volume control settings, the relationships being such that for a range of volume control settings less than a first setting the gain of the center front channel remains substantially constant while the gain of the other channels decreases as the setting decreases or decreases more gradually than the gain of the other channels as the setting decreases.

The invention claimed is: 
     
       1. A motion picture soundtrack reproduction system, the system having a center front soundtrack channel and a plurality of other soundtrack channels, comprising
 a controller having a volume control for adjusting the gain of all the channels, the volume control having a range of settings from a minimum to a maximum, the controller having a first output for controlling the gain of the center front channel and a second output for controlling the gain of the other channels in response to settings of the volume control, the gain of the center front channel having a first relationship to the volume control settings and the gain of the other channels having a second relationship to the volume control settings, the relationships being such that for a range of volume control settings less than a first setting the gain of the center front channel (1) remains substantially constant while the gain of the other channels decreases as the setting decreases, or (2) decreases more gradually than the gain of the other channels as the setting decreases.   
     
     
       2. A motion picture soundtrack reproduction system, comprising
 a center front soundtrack channel and a plurality of other soundtrack channels, each of said channels having adjustable gain and one or more loudspeakers, and   a controller having a volume control for adjusting the gain of all the channels, the volume control having a range of settings from a minimum to a maximum, the controller having a first output for controlling the gain of the center front channel and a second output for controlling the gain of the other channels in response to settings of the volume control the gain of the center front channel having a first relationship to the volume control settings and the gain of the other channels having a second relationship to the volume control settings, the relationships being such that for a range of volume control settings less than a first setting the gain of the center front channel (1) remains substantially constant while the gain of the other channels decreases as the setting decreases or (2) decreases more gradually than the gain of the other channels as the setting decreases.   
     
     
       3. A system according to  claim 1  or  claim 2  wherein the range of volume control settings less than said first setting extends down to the minimum control setting. 
     
     
       4. A system according to  claim 1  or  claim 2  wherein the range of volume control settings less than said first setting extends down to a second setting above the minimum control setting. 
     
     
       5. A system according to  claim 3  wherein for settings less than said second setting the gains of all the channels decrease in substantially the same way as the setting decreases and for such volume control settings the gain of the center front channel is greater than the gain of the other channels. 
     
     
       6. A system according to  claim 5  wherein for settings less than said second setting the gain of the center front channel is greater than the gain of the other channels by a substantially constant amount in the logarithmic domain. 
     
     
       7. A system according to  claims 1  wherein for settings greater than said first setting the gains of all the channels increase as the setting increases and for each of such volume control settings the gain of the center front channel and the gain of the other channels are substantially the same. 
     
     
       8. A system according to  claims 1  wherein when the volume control is set to a standard setting, each of the channels has a respective gain that produces a respective standard acoustic level in response to a signal having a respective standard reference level in the channel. 
     
     
       9. A system according to  claim 8  wherein said first setting is about said standard setting. 
     
     
       10. An audio system, comprising:
 a first channel and a second channel, each of said channels having a gain;   a controller having a volume control for adjusting the gain of the first channel and the gain of the second channel, the volume control having a range of settings from a minimum to a maximum, the gain of the first channel having a first relationship to the volume control settings and the gain of the second channel having a second relationship to the volume control settings, the relationships being such that for a range of volume control settings less than a first setting the gain of the first channel (1) remains constant while the gain of the second channel decreases as the volume control setting decreases below said first setting or (2) decreases more gradually than the gain of the second channel as the volume control setting decreases below said first setting;   a matrix decoder to derive a first channel output and a second channel output.   
     
     
       11. The audio system of claim 10, wherein the range of volume control settings less than said first setting extends down to the minimum control setting. 
     
     
       12. The audio system of claim 10, wherein the range of volume control settings less than said first setting extends down to a second setting above the minimum volume control setting. 
     
     
       13. The audio system of claim 12, wherein for volume control settings less than said second setting the gains of the first and second channels are attenuated equally as the volume control setting decreases below said second setting and for such volume control settings the gain of the first channel is greater than the gain of the second channel. 
     
     
       14. The audio system of claim 10, wherein the matrix decoder derives the first channel output and the second channel output from a two-channel soundtrack.