2.1 Digital Signal Processor
A Digital Signal Processor (DSP) is used to perform speech and audio processing. The advanced speech features, such as acoustic echo cancellation and noise reduction, are built-in. To reduce nonlinear distortion and to help echo cancellation, an outgoing signal level to the speaker is monitored and adjusted to avoid saturation of speaker output or microphone input. To provide an echo free and full-duplex user experience, adaptive filtering is also applied to track the echo path impulse in response.
The embedded noise reduction algorithm helps to extract clean speech signals from the noisy inputs captured by microphones and improves mutual understanding in communication. The advanced audio features, such as multi-band dynamic range control, parametric multi-band equalizer, audio widening and virtual bass are built-in. The audio effect algorithms improve the user’s audio listening experience in terms of better quality audio after audio signal processing.
The following figures illustrate the processing flow of speaker phone applications for speech and audio signal processing.
- LDAC decoder in the preceding figure is supported only in the IS2064GM-0L3 variant.
For SBC and AAC audio data, the DSP parameters such as EQ, Speaker Gain, Mic Gain, Sound Effect etc. are configured using the DSP tool. For additional information on the DSP tool, refer to the “IS206x DSP Application Note”.