Signal — #01


Author: Ben Clarke
Technical Support Manager
Smaart Instructor
Production Audio Video Technology

Everything I don’t want is noise. Our world is filled with noise. Our brain is programmed with the finest signal processing ability to filter it out and focus on a wanted signal – but with it comes listener fatigue.

Noise presents in many forms, but for me its best described as ‘Everything I don’t want” and when considering any audio system or application it’s often the number one reason a client considers an outcome acceptable or unacceptable.

What noise? There are so many…

Ambient Noise – often when describing the ‘ambient noise floor’ we are defining things that are constant in our room or space, but it’s not always constant. The ambient noise can change quite drastically, by anything from variable air conditioning noise as the thermal load changes to peak traffic running past your window. Projector systems turning on, laptops coming in, even participants in the room talking. Plenty of everything I don’t want.

Reverberation – in many cases reflected audio can be regarded as noise because it may often be unwanted.

System Self Noise – an incorrectly set signal gain structure can raise the unwanted noise floor of your electronics when you get to the audible end. Equipment with high RPM fans can be audible if in very quiet environments. Interference from colliding RF transmitter/receiver settings, induced RF interference from non-RF immune electronics, digital signals losing synchronization. One of my favorite self noises is when there’s a return loop of audio within an system chain… so much of everything I don’t want.

Too often when designing, installing or supporting systems we forget to consider the noise – or worse, commit ourselves to relying on “something” to work around it or “fix” it. A problem is most efficiently and effectively resolved at its source. If your audio system is exhibiting any of the above traits I describe as noise and it’s affecting your outcome – nothing beats reducing or eliminating the noise source. This can very rarely be done after a lengthy design process. The greatest misunderstanding of the modern audio system process is expecting a technician at the end of the chain to deal with it through some form of signal processing - regardless of skill.

The false economy is expecting to “add a component”, turn on a “check box” or change a “DSP parameter” to resolve any noise. The more you do to your wanted signal to try to eliminate noise after its happened can only reduce the quality of the wanted noise, which in the end is not the outcome we wanted either.

For me, poor quality of a wanted signal is the biggest unwanted and fatiguing noise of all, so it’s always my fundamental consideration when discussing any system.