Agere Systems Inc.

Rupinder Judge

Richard Verney

Robert O Peruzzi

Tie Liu

An electronic audio device with a digital audio output channel in which an amplifier output voltage is gradually ramped up and down to avoid causing a popping sound when the device is turned on and off. This is accomplished without employing any additional hardware, by incrementally changing a digital input word applied to a digital audio source, such as a DSP, so as to gradually change the amplifier output voltage between a minimum, such as zero volts, and a DC working voltage. On powering up, the amplifier is only turned on after the digital word is applied, but while it still results in a minimum amplifier output, and on powering down the amplifier is turned off after it's output has been ramped down, but before removing the digital input word. Sources and output channels can also be switched over by powering down, and then powering up, following the same method.

Prevention of audio pop in a digital audio device

Speech recording is effected in a GSM phone handset ( ) by storing in a memory ( ) speech frames during the presence of speech, one or more SID frames during the absence of speech, and data representative of the duration of the absence of speech. In this way memory ( ) does not store silent speech frames, and utilisation of memory space is therefore particularly efficient. In addition, items such as a voice activity detector and a comfort noise estimator, which are already provided in the handset as part of the GSM system, are &ldquo;re-used&rdquo; by the invention, thereby making efficient use of already-provided hardware/software.

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Binfield, United Kingdom

Rupinder Judge