Feature: Consumer electronics
Intelligent algorithms Algorithms are purpose-designed to capture a clean voice command in a modern – and oſt en noisy – living space. T e digital signal processing pipeline (Figure 1) captures voice from
noise and cleans it up so the command can be processed by an ASR service, like Amazon Alexa. When a voice command is spoken to the TV set, in most cases
it’s already playing some audio. In the background there could be a phone ringing, people talking, kitchen appliances and air conditioning whirring, and a range of other noises from outside the room – traffi c rumble, animal sounds, and so on. It’s quite the challenge to extract voice commands from all that. T e system is always listening for the wake-word, e.g. “Alexa” or
“TV”. T e stereo acoustic echo canceller suppresses any audio stream that’s playing through the device itself to enable a “barge in” – when it hears the wake word, the system immediately mutes the audio track. T e Automatic Delay Estimator synchronises an audio reference signal with the microphone audio to support a smooth real-time barge-in action. T e interference canceller scans the soundscape of the room and
suppresses the point noise sources (all the steady noise that comes from a fi xed direction). Noise suppression reduces the diff use noise, isolating and subtracting those sounds from the signal to give further clarity to the voice command. Lastly, the Automatic Gain Control tailors the audio stream for the output channel. T e quality of all these algorithms working both individually and
together, is crucial; they make the system wake up on command and capture the voice signal clearly so the speech recognition system can process and respond to it accurately.
Intelligent voice interfaces Far-fi eld voice is just the start. Intelligence and improved security in voice interfaces will continue to change the way we interact with TVs and content. Intelligent sensors will alert the TV set to a person’s entry into the room and bring the device from deep sleep to command readiness. T e TV will not only identify the person in the room but have the intelligence to apply each user’s preferences to the content, freeing them from complex menu structures. Intelligent voice interfaces will enable eff ective multi-tasking in the
smart home. Controlling the TV will be eff ortless, without having to stop other activities such as checking the phone for messages, cooking, etc.
One day, our children will look upon the remote control as quizzically as they do the cassette tape today.
In-built voice With a television now in most rooms of the home, it’s still the prime candidate to be the central smart-home hub. Built- in voice will enable it to connect to an ecosystem of smart devices, including lights, appliances and security systems, all controlled by simple voice commands. Voice is definitely the future of television control.
It will be an end of an era when the remote control is replaced by voice
Figure 1: DSP pipeline for capturing voice from noise in remote control applications
www.electronicsworld.co.uk September/October 2020 55
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