Most of the interest in modern TV broadcasting technology goes into the picture. However, sound is an equally important factor for the user experience, and some of the most important tools for making good sound are audio monitors.
Perhaps a tangible way to describe audio monitoring for TV broadcasting people is to make a comparison with video monitoring. What the video engineer does with color balance is what the audio engineer does with the balance between audio frequencies. Obviously, this does not come as a surprise to many people in our industry. Even so, it seems that those same people have something to learn as we constantly see poor audio monitor installations in the field. This article discusses some of these issues.
Once you call something a monitor, it is pretty clear we are talking about some sort of surveillance process. In the case of audio monitoring, it can mean different things. As mentioned above, one meaning, of course, is to control the balance, while another can be to listen and correct inaccuracies or faults. Monitoring also can be both of these together. For example, at the London Olympics International Broadcasting Centre, there were two 5.1 surround rooms where the task was to listen to the 5.1 signal quality just before it went on air. Like the video engineer needs his expensive video monitor with exact colors, the audio engineer needs a tool that is equally exact and reliable in reproducing the audio signal perfectly. A monitoring speaker is a quality-control tool used to judge the technical and artistic quality of the program. This definition is wide, and we next will look at what it means.
The key issues for any tool are reliability, consistency and fitting to the purpose. Reliability means both technical reliability (fault-free operation for a long time) and performance reliability (actual performance does not change in use). Consistency demands that unit-to-unit variation is small between units during the whole lifetime of individual products and production lots. Fitting to the purpose asks for thorough understanding of the conditions where the products are to be used, and what those conditions mean in performance features.
In the market today, we can find a large number of loudspeakers called monitors or reference monitors. Some of them are good, but, unfortunately, not all deserve the name. To be called an audio monitor or a reference monitor, the performance must be known. In short, we need to know the frequency response of the monitor at the listening position. The position is where the sound engineer works.
Some engineers, sadly, think that a manufacturer’s published frequency response in a data sheet is sufficient. Mostly, this is measured in a controlled environment like an anechoic chamber, where there are no mixing consoles, DAWs, flat screens, equipment racks or anything else that has an influence on frequency response. If properly measured, these graphs tell valuable information like distortion, maximum sound pressure level, etc. But, for example, the frequency response measurements have limited value in a real-world environment like a control room. Here, we have one important requirement for a monitoring speaker to fit to its purpose: You must be able to acoustically align it in the room where you will use it. To do so, the monitoring speaker must have the ability to be adjusted, and you need some kind of acoustic measurement tool that can look at the signal in the time and frequency domains. You also need some understanding regarding what the measurements mean.
A real-time analyzer can only give a rough idea, as it measures both direct sound and reflected sound, but does not allow for looking at the signal in time domain. Luckily, there are several software programs available that turn a laptop and good microphone into a proper measurement device.