Audio processing for broadcast is one of the most necessary, but least understood, tools we use to make our programs come across consistently loud, clear, and inviting.

Speech and music can vary from extremely quiet to very loud. But radio listeners are usually in environments where this wide range between loud and soft is not what we want. In an office or car, the general noise level would prevent the quiet sounds from being heard… they need to be increased above the background. And overly-loud bursts of sound would be distracting… they need to be held down to a reasonable level.

In other words, we want to compress the range between loudest and quietest. OK, fine. There are several audio compressors in the music stores for a couple hundred bucks. Won’t they work?

NO. Let me put that another way… NO. Compressors made for live music generally don’t respond to spoken voice or pre-recorded program material in a way that is appropriate for broadcasting.

They typically react too slowly to follow speech. For example: a burst of loud speech comes by, and the compressor responds too late to control the loudest part. By the time it has adjusted the level down, the loud part has already gone. Now the volume is too low for the current condition, so those words are difficult to hear. You hear the beginning of a word, followed by a noticeable “hole” in the audio while the compressor catches up to the average sound level. You will also hear this behavior when too much compression is used in an attempt to make the music sound louder. Not very professional- sounding.

Some engineers have the skill to adjust basic audio compression with few negative side effects. But most people don’t have the patience or desire to work at it. The best choice is to use audio processing gear made specifically for broadcast purposes.

Automatic level control is commonly used to ensure that audio coming from an outside source is captured at an optimal level. For unattended capture of syndicated network programs and news feeds, popular models are Inovonics 261, Aphex 320D, and RDL STGCA3. They automatically (and inaudibly) increase the level of “too quiet” material, and reduce the “too loud” stuff, for a consistent recording. This prevents distortion and excessive background noise, and will reduce the “swirly” sounds often associated with streaming audio.

Microphone processors provide several functions to enhance, brighten, and keep the announcer’s voice at a consistent level, while reducing room noise. Popular models are here.

After the sound leaves your mixing console, it will typically pass through a broadcast audio processor by Orban, Omnia, Wheatstone, Inovonics, or Audemat. There are models specifically for AM, FM, HD, and internet streaming.

In general terms, the high-end models ($10K+) are used by the largest stations in the most competitive markets. These are the machines that do battle in the “loudness wars” with every trick the manufacturers can develop to be just a little bit louder than the other guy.

The lower cost processors (below $10K) do an excellent job for most stations. They differ mostly in the number of separate bands of compression or limiting. In general terms, the processors with more bands of limiting can give more detailed and “natural” sound with the fewest side effects as you push them to their maximum loudness.

With so many stages of adjustment possible, it can be very intimidating to set up a new processor. Luckily, the folks that make these processors are fanatics, devoted to making the best possible sound they can with their equipment. They spend endless months developing the presets contained in these processors. I strongly recommend using one of the factory-installed presets for the best results.

I know, it’s tempting to fiddle with the controls to make your own “signature sound”… but most of us aren’t sure what to adjust to achieve the sound we want. Trust me, unless you are a true processing geek, factory presets are the way to go.

Give us a call. Let us know what format you play. We’ll help you decide on the appropriate audio processor combination for your situation.


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