Patent ID: 9008319
Filing Date: 2015-04-14
Classification: H03G

Abstract:
1. An audio processing system, the system receiving input signals, comprising: a delta incident detector configured to detect delta acoustic incidents in the input signals that exceed a predetermined acoustic startle boundary; a delta limiter configured to determine an anti-startle gain in response to the delta incident detector detecting a delta acoustic incident, the anti-startle gain having an anti-startle gain limit and an anti-startle release time associated therewith; an amplifier configured to apply the anti-startle gain to the input signal; wherein the delta incident detector includes: a fast lowpass filter associated with a short time constant and configured to generate mean square sound levels associated with the short time constant from input signals; a medium lowpass filter associated with a medium time constant that is larger than the short time constant and configured to generate mean square sound levels associated with the medium time constant from input signals; a first comparator that compares a ratio between the mean square sound level outputs from the fast and medium lowpass filters to a first predetermined delta incident detection threshold to determine whether the input signals exceed the predetermined acoustic startle boundary; a slow lowpass filter associated with a long time constant that is larger than the medium time constant and configured to generate mean square sound levels associated with the long time constant from the input signals, the slow lowpass filter facilitates in measuring a recent average signal level and is further configured to be selectively enabled and disabled; and a second comparator that compares a ratio between the mean square sound level outputs from the fast and slow lowpass filters to a second predetermined delta incident detection threshold, the second comparator facilitates in preventing false triggering of the delta incident detector during normal speech.