Audio equipment
US4641344A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 4, 1985 |
| Grant date | Feb 3, 1987 |
| Priority date | — |
| Expiry date | Jan 4, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G5/165
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Audio equipment designed for use at widely varying ambient noise levels allows an audio signal to be amplified to enhanced levels under noisy conditions without added distortion near the high-amplitude end of its dynamic range. Detected or anticipated ambient noise conditions trigger a dynamic range controller to boost the gain of the audio signal to an extent inversely related to the audio signal amplitude. Thus, low-volume audio will be boosted to a great extent while the high-volume end of the dynamic range will experience little or no additional gain. The net effect is two allowable dynamic ranges, both sharing the same high-end volume level but with possibly widely different low-end volume levels. This gain and dynamic range control may also be performed independently on a number of discrete frequency bands. In addition, noise components inherent to the audio signal may be filtered to ambient noise-dependent extends, or the gain boost may be inhibited at volume levels susceptible to such noise.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.