AVQ Automatic Volume and eQqualization control Interactive White Paper v1.6
2 Revision: 2.0 Figure on the right shows the basic AVQ scheme. A microphone (already present in communication devices) is used to monitor the current noise conditions. The signal being equalized is divided on several frequency subbands. The microphone signal is divided on the same frequency subbands and analyzed to extract noise level in each subband without being affected by the loudspeaker sound. The parameters are then fed into the corresponding band equalization (gain) blocks. These blocks dynamically amplify and equalize the sound to be head equally well in varying noisy conditions ensuring sufficient but not excessive signal to noise ratio over all frequency range. Mobile phones Hands-free kits Car radios Portable Media Players Comfortable reproduction of music or speech in varying noisy conditions requires constant changes in sound level (with changes in noise level) and equalization (with changes in noise spectrum). For example, the volume and equalization set for a standing car will no be adequate when the car is moving. Today, the user has to change the sound volume manually which is uncomfortable and, in some cases such as a hands-free car kit, even dangerous. Suitable manual frequency equalization is almost never possible due to a large number of parameters to control “on the fly”. Demo ahead The problem and solution Automatic Volume eQualization control (AVQ) technology provides an automatic alternative to manual volume and equalizer adjustment. It permanently monitors noise conditions and changes the sound being reproduced accordingly. Decomposition on subbands Band Noise Estimation Decomposition on subbands Band EQ 1 Gain > 1 Band EQ N Gain = 1 Combining from bands Noise level Signal and noise before Signal and noise after Input signal Mic signal
3 Revision: 2.0 The figures below illustrates the performance The left figure shows sound and noise level in quiet conditions (e.g. in a standing car). The volume and equalization of speech is set to be heard well (all above the noise level but not too much). The middle figure shows the same speech level while the noise level and its spectrum has changed (moving car). It is seen that parts of the speech spectrum are masked by noise. Accordingly, the speech intelligibility is reduced dramatically. The right figure demonstrates the spectrum of noise and equalized speech. Similar to the left figure, the speech exceeds the noise level all over the frequency range (but not too much). This restores intelligibility and provides a comfortable sound. Demo on the next slides AVQ Performance AVQ may also be called “Audio Cruise Control” as it totally eliminates the need to touch sound controls while “cruise” conditions are changing.
4 Revision: 2.0 AVQ processing for voice communication BulldozerHelicopter Press any key to hear unprocessed sound Press any key to hear sound with AVQ BulldozerHelicopter Voice in ambient noise without processing Voice in ambient noise with AVQ processing Demo conditions: - Varying background noise is an ambient noise around the user. It cannot be changed/reduces as the DSP system has not control of it. - Voice reproduced by the phone speaker is equalized according to the spectrum and power of the ambient noise to provide equal intelligibility and perceptual loudness. Being a part of Alango Voice Communication Package of technologies (VCP), AVQ technology is tightly integrated with other Alango signal processing technologies. It shares the same subband decomposition and noise estimation blocks.
5 Revision: 2.0 AVQ-Me processing demo for music AVQ for Music and Entertainment (AVQ-Me) is devoted to those listening music, watching movies and using their game consoles in mobile environments. While ambient noises change fast and unpredictable, you just don’t have time to stop. AVQ-Me does all for you, so enjoy your music, always. Without AVQ-Me Processed by AVQ-Me technology Noise in the examples is ambient noise. AVQ-Me cannot reduce or change it, it amplifies and equalizes the music instead AVQ for Music and Entertainment (AVQ-Me) technology uses its own subband decomposition scheme that is optimized for high quality music reproduction in such devices as portable media players, mobile phones and car stereos.