Abstract: A sigma delta digital-to-analog (D/A) converter system (10) includes a summing device (35) at an input of a D/A converter (30), and a low frequency low amplitude wave signal (31) injected at an input of the summing device that remains unfiltered and is used to suppress spurious tone artifacts. The D/A converter system can further include an amplitude control and a frequency control for selectively adjusting the frequency and the amplitude of the low frequency low amplitude wave signal being injected. Note, the low frequency low amplitude repeating wave signal generator can take the form of a digital signal processor (DSP) (37) having the appropriate software to generate such signals.

Abstract: A method, system and computer readable medium for increasing the audio perceptual loudness includes shifting at least one frequency of a first audio signal to create a second audio signal so as to increase the audio perceptual loudness. The power level of the second audio signal is not more than a power level of the first audio signal. The method also includes generating high-audio perceptual loudness tone alert sequences based on psychoacoustic and audiometric data. It further includes acquiring a listener's threshold audio profile; adding the listener's audio profile to the loudness sensitivity curve for producing the listener's tonal sensitivity curve; determining a required dB scaling for critical band tones from the listener's tonal sensitivity curve; normalizing the tonal sensitivity curve for creating a decibel curve; selecting a frequency range of the tones by using the tonal sensitivity curve; and spacing the sequence of tones along a critical band scale.

Abstract: The invention concerns a method (300) and system (100) for controlling audio output. The method includes the steps of inputting (312) an audio signal and a voltage level signal, measuring (314) the audio signal and the voltage level signal, mapping (316) the audio signal against at least one table (134) of predetermined corresponding gain targets (138) and selecting (318) at least one gain target for the audio signal. The mapping step and the selecting step are based at least in part on the measurement of the voltage level signal and the measurement of the audio signal. The method also includes the step of applying (320) the gain target to the audio signal.

Abstract: A stereo headset (104) with push-to-talk function can be interfaced with a wireless communication device (102) via a connector interface. The connector interface preferably includes a jack at the wireless communication device (102) and a compatible plug at the stereo headset (104). An electrical contact (310) at the connector interface can contemporaneously interconnect both electrical audio signals between the wireless communication device (102) and at least one of the speakers of the stereo headset (104) and electrical user input signals from an external push-to-talk user input device (232) to the wireless communication device (102).