Abstract: A system for thermally protecting an amplifier driving a capacitive load may include a low-pass filter configured to filter, with a variable cutoff frequency, an input signal to generate a filtered input signal, wherein the amplifier is configured to receive the filtered input signal and amplify the filtered input signal to generate a driving signal to the capacitive load and a controller configured to receive a real-time estimate of a temperature associated with the amplifier and vary the variable cutoff frequency as a function of the temperature.

Abstract: A method for controlling one or more parameters of an amplifier system may include receiving an indication of a physical quantity associated with the amplifier system, determining one or more parameters of the amplifier system in response to the indication, and causing the amplifier system to operate in accordance with the one or more parameters.

Abstract: A spectral tilt of an audio signal is used to determine whether a speaker will introduce perceptible distortion during playback of the audio signal. The spectral tilt may be indicated by determining a ratio between energy in a distortion-producing frequency band and energy in a distortion-masking frequency band. Based on the determined spectral tilt, the distortion-producing frequency band may be attenuated to reduce the distortion introduced by the speaker. Additionally, the distortion-masking frequency band may be amplified to reduce perceptibility of the distortion produced by the speaker.

Abstract: Audio distortion by a speaker may be reduced by detecting onset audio events within an audio signal and modifying the audio to reduce the audio distortion perceived by a listener. The onsets may be detected using a psych-acoustic model by determining critical sub-band powers and corresponding masking thresholds. When a loudness value calculated from the CSBs and masking thresholds exceeds a threshold level, certain frequency bands may be attenuated and other frequency bands may be amplified. The audio modification may be performed on a frame-by-frame basis and each frame may be processed multiple times until the onset is sufficiently masked or attenuated.

Abstract: A spectral tilt of an audio signal is used to determine whether a speaker will introduce perceptible distortion during playback of the audio signal. The spectral tilt may be indicated by determining a ratio between energy in a distortion-producing frequency band and energy in a distortion-masking frequency band. Based on the determined spectral tilt, the distortion-producing frequency band may be attenuated to reduce the distortion introduced by the speaker. Additionally, the distortion-masking frequency band may be amplified to reduce perceptibility of the distortion produced by the speaker.

Abstract: Embodiments described herein provide an audio device and a method of operating the audio device. The audio device comprises at least one surface, a first surface transducer positioned to excite first modes of oscillation in a first surface of the at least one surface, and a second surface transducer positioned to excite second modes of oscillation in a second surface of the at least one surface, wherein the first modes of oscillation are of a higher frequency than the second modes of oscillation.

Abstract: A system may include an input configured to receive a first signal representative of a second signal to be driven to an amplifier input of an amplifier, processing circuitry configured to process the first signal in order to generate the second signal from the first signal such that the processing circuitry limits a current driven by the amplifier to an output load of the amplifier, and an output configured to drive the second signal to the amplifier input.

Abstract: A bass enhancement may be applied to improve the perception of low-frequency sounds by a user of an electronic device. A distortion function may be applied to the audio signal that results in creation of higher frequency content related to the low-frequency sounds. This higher frequency content may be interpreted by a listener's ear in a similar manner as the low-frequency sounds. The distortion function may be a Sigmoid function. Bass enhancements may also include scaling of the audio signal prior to distortion, adaptation of the distortion, or gap band filtering prior to the distortion.

Abstract: A system for vaporizing and optionally decomposing a reagent, such as aqueous ammonia or urea, which is useful for NOx reduction, includes a cyclonic decomposition duct, wherein the duct at its inlet end is connected to an air inlet port and a reagent injection lance. The air inlet port is in a tangential orientation to the central axis of the duct. The system further includes a metering valve for controlling the reagent injection rate. A method for vaporizing and optionally decomposing a reagent includes providing a cyclonic decomposition duct which is connected to an air inlet port and an injection lance, introducing hot gas through the air inlet port in a tangential orientation to the central axis of the duct, injecting the reagent axially through the injection lance into the duct; and adjusting the reagent injection rate through a metering valve.

Abstract: In a large exhaust duct from a lean burn combustion source, such as a boiler, diesel engine or gas turbine, multiple injectors can be used to inject a reagent, such as an aqueous solution of urea or ammonia, into the exhaust for use in the catalytic reduction of NOx in a process known in the art as selective catalytic reduction (SCR). When operating at low injection rates, such as during low combustor loads, the injectors are operated individually for short periods of time in a sequential manner.

Abstract: A system for vaporizing and optionally decomposing a reagent, such as aqueous ammonia or urea, which is useful for NOx reduction, includes a cyclonic decomposition duct, wherein the duct at its inlet end is connected to an air inlet port and a reagent injection lance. The air inlet port is in a tangential orientation to the central axis of the duct. The system further includes a metering valve for controlling the reagent injection rate. A method for vaporizing and optionally decomposing a reagent includes providing a cyclonic decomposition duct which is connected to an air inlet port and an injection lance, introducing hot gas through the air inlet port in a tangential orientation to the central axis of the duct, injecting the reagent axially through the injection lance into the duct; and adjusting the reagent injection rate through a metering valve.

Abstract: A system for vaporizing and optionally decomposing a reagent, such as aqueous ammonia or urea, which is useful for NOx reduction, includes a cyclonic decomposition duct, wherein the duct at its inlet end is connected to an air inlet port and a reagent injection lance. The air inlet port is in a tangential orientation to the central axis of the duct. The system further includes a metering valve for controlling the reagent injection rate. A method for vaporizing and optionally decomposing a reagent includes providing a cyclonic decomposition duct which is connected to an air inlet port and an injection lance, introducing hot gas through the air inlet port in a tangential orientation to the central axis of the duct, injecting the reagent axially through the injection lance into the duct; and adjusting the reagent injection rate through a metering valve.

Abstract: In a large exhaust duct from a lean burn combustion source, such as a boiler, diesel engine or gas turbine, multiple injectors can be used to inject a reagent, such as an aqueous solution of urea or ammonia, into the exhaust for use in the catalytic reduction of NOx in a process known in the art as selective catalytic reduction (SCR). When operating at low injection rates, such as during low combustor loads, the injectors are operated individually for short periods of time in a sequential manner.

Abstract: The present synthesizer generates an underlying spectrum, pitch and loudness for a sound to be synthesized, and then combines the underlying spectrum, pitch and loudness with stored Spectral, Pitch, and Loudness Fluctuations and noise elements. The input to the synthesizer is typically a MIDI stream. A MIDI preprocess block processes the MIDI input and generates the signals needed by the synthesizer to generate output sound phrases. The synthesizer comprises a harmonic synthesizer block (which generates an output representing the tonal audio portion of the output sound), an Underlying Spectrum, Pitch, and Loudness (which takes pitch and loudness and uses stored algorithms to generate the slowly varying portion of the output sound) and a Spectral, Pitch, and Loudness Fluctuation portion (which generates the quickly varying portion of the output sound by selecting and combining Spectral, Pitch, and Loudness Fluctuation segments stored in a database).

Abstract: The present synthesizer includes functionality for changing over from a current note to the following notes that results in natural and expressive combinations and transitions. The method of the present invention incorporates an delay (actual, functional, or look ahead) between receiving control data inputs and generating an output sound. This period of delay is used to modify how notes will be played according to control data inputs for later notes. The input to the synthesizer is typically a time-varying MIDI stream, which may be provided by a musician or a MIDI sequencer from stored data. An actual delay occurs when the synthesizer receives a MIDI stream and buffers it while looking ahead for changeovers between notes. A functional delay occurs in a system in which the synthesizer has knowledge of note changeovers ahead of time.

Abstract: The present invention is a musical synthesizer that can respond to a pitch wheel control by generating realistic slide-step-slide and slide-step portamento pitch curves. The musical synthesizer responds to a pitch wheel control in a context sensitive manner. When a first note-on occurs the pitch wheel behaves in the standard fashion. However, when a second-note on occurs, if the pitch wheel is still being held after the second note-on then the effects of the pitch wheel are disabled. The result is a clean slide-step portamento curve. In addition, the effects of the pitch wheel are delayed slightly relative to the raw pitch wheel signal. The result is that if the pitch wheel is released slightly before a second note-on occurs then the delayed pitch wheel signal will still be at substantially the previous held value when the second note-on occurs. The result is a clean slide-step portamento curve.

Abstract: The present invention is a musical synthesizer that can respond to a pitch wheel control by generating realistic slide-step-slide and slide-step portamento pitch curves. The musical synthesizer responds to a pitch wheel control in a context sensitive manner. When a first note-on occurs the pitch wheel behaves in the standard fashion. However, when a second-note on occurs, if the pitch wheel is still being held after the second note-on then the effects of the pitch wheel are disabled. The result is a clean slide-step portamento curve. In addition, the effects of the pitch wheel are delayed slightly relative to the raw pitch wheel signal. The result is that if the pitch wheel is released slightly before a second note-on occurs then the delayed pitch wheel signal will still be at substantially the previous held value when the second note-on occurs. The result is a clean slide-step portamento curve.

Abstract: The present synthesizer generates an underlying spectrum, pitch and loudness for a sound to be synthesized, and then combines the underlying spectrum, pitch and loudness with stored Spectral, Pitch, and Loudness Fluctuations and noise elements. The input to the synthesizer is typically a MIDI stream. A MIDI preprocess block processes the MIDI input and generates the signals needed by the synthesizer to generate output sound phrases. The synthesizer comprises a harmonic synthesizer block (which generates an output representing the tonal audio portion of the output sound), an Underlying Spectrum, Pitch, and Loudness (which takes pitch and loudness and uses stored algorithms to generate the slowly varying portion of the output sound) and a Spectral, Pitch, and Loudness Fluctuation portion (which generates the quickly varying portion of the output sound by selecting and combining Spectral, Pitch, and Loudness Fluctuation segments stored in a database).

Abstract: The present synthesizer includes functionality for changing over from a current note to the following notes that results in natural and expressive combinations and transitions. The method of the present invention incorporates an delay (actual, functional, or look ahead) between receiving control data inputs and generating an output sound. This period of delay is used to modify how notes will be played according to control data inputs for later notes. The input to the synthesizer is typically a time-varying MIDI stream, which may be provided by a musician or a MIDI sequencer from stored data. An actual delay occurs when the synthesizer receives a MIDI stream and buffers it while looking ahead for changeovers between notes. A functional delay occurs in a system in which the synthesizer has knowledge of note changeovers ahead of time.

Abstract: An efficient synthesizer of tonal audio signals is disclosed. The tonal audio signal synthesizer utilizes additive synthesis of harmonics of the base frequency. Rather than generating and summing all of the individual frequency sinusoidal harmonics as in traditional additive synthesis, critical band signals (comprising multiple harmonics added together) are generated, and the critical bands are summed based upon the Critical Bands resolvable by human hearing. Each critical band signal comprises the combination of from one to many sinusoids, generally of equal amplitude. Generally only a single harmonic is included in the lowest critical band, or the lowest several critical bands. As the frequency increases, the number of harmonics in each critical band increases as well. A gain is applied to each critical band signal.