Len LaytonGlobal Business Development Manager, Acoustics, BlackBerry
If you’ve ever had to “twist and shout” to be heard by back seat passengers then listen up – you might find some new technology from QNX useful (and safer!)
So many cars already have the basic hardware that we could leverage to effectively make a phone call to the people in the back of the vehicle. The handsfree microphone can pick up the driver’s voice, amplify (reinforce) it and play it out of the rear loudspeakers near to the people in the back. This is the principle of in-car communications -- “ICC” for short.
Designing a practical in-car communications (“ICC”) system can be broken down into a few basic steps. But first let’s look at how a car’s hardware is setup and the paths where audio will be flowing. The main problem is the “front-to-back” case where the driver’s voice needs to be reinforced for the benefit of the passengers in the back, to that the driver doesn’t have to twist around and shout at the people in the back.
You can see that we have essentially built a public address system for the car.
In noisy conditions we could turn on the ICC system and then the voice of the driver should be heard much more clearly. Sound would be flowing through the “reinforced path” in the diagram. At intermediate noise levels, the listener in the back will be able to hear both the direct path and the reinforced bath at the same time.
If there is too much time delay between these two paths, then the listener will perceive the reinforced signal as though it was someone else talking and will not sound natural at all. Studies have suggested that any more than about 30 milliseconds is the limit of this time delay between the direct and reinforced paths.
There will also be some of the reinforced signal that comes back to the talker in the form of echo, which can be disturbing or annoying for the talker if there is too much delay on this path too. And let’s not forget the key issue we are dealing with – NOISE! Noise is all around the occupants and the faster you go the more noise there is. So, what should we care about when designing and ICC system?
QNX ICC is the first practical seat-to-seat speech enhancement software product. It addresses the whole set of challenges faced when implementing a practical ICC system:
1) Improved intelligibility by reinforcing speech naturally without distortion or added noise. QNX ICC addresses the primary goal of an ICC system – replacing the “What?” with “Oh Yeah!”2) fully Automatic - the amount of reinforcement is continuously adapted to the actual noise level in the car. So as different noise conditions are experienced, the reinforcement is immediately and smoothly adjusted and the driver does not need to operate any controls at all. QNX ICC is truly “set and forget” and can be safely left enabled so that it is ready to kick-in as needed.
3) No feedback howling Under any circumstances QNX ICC will never howl.
4) No Echo or unpleasant perceptible effects – QNX ICC operates at low delay so the talker will only perceive that their voice is slightly louder and not delayed or sounding “processed.”
5) low delay operation so that reinforced speech does not perceptibly interfere with direct, non-reinforced speech. QNX ICC’s algorithmic latency is only 5 milliseconds.
6) Reinforces speech only and does not amplify background noise. Leveraging more than a decade of experience and over a hundred patents in the area of automotive signal processing, QNX ICC includes advanced noise reduction algorithms to ensure clear and natural speech reinforcement.
7) Simultaneous operation with music and not cause any perceptible distortion to music or other media playback.
8) Implementable on current ICs such as infotainment processor CPUs and DSPs and co-exist with other system software.
9) Tuning that is easy and quickly adapted for different vehicle types and acoustic configurations before production.
QNX ICC is available for licensing today either as a standalone signal processing library or as part of QNX’s new Acoustics Management Platform ("AMP"). QNX In-Car Communications is one of the great features of the breakthrough QNX Acoustics Management Platform click here to find out more.
A future blog post will address how QNX ICC can be integrated with a complete automotive acoustics solution.
