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Everything we do is destined for one place.

I give you, The Human Ear:

Anatomy of the human ear

Anatomy of the Human Ear, courtesy of Wikipedia

All of the programming elements, all of the engineering equipment and practices, all of the creative process, the music, the talk, the commercials, everything that goes out over the air should reach as many ears as possible.  That is the business of radio.  The quality of the sound and the listening experience is often lost in the process.

Unfortunately, a large segment of the population has been conditioned to accept the relatively low quality of .mp3 and other digital files delivered via computers and smart phones.  There is some hope however; when exposed to good sounding audio, most people respond favorably, or are in fact, amazed that music can sound that good.

There are few fundamentals as important as sounding good.  Buying the latest Frank Foti creation and hitting preset #10 is all well and good, but what is it that you are really doing?

Time was when the FCC required a full audio proof every years.  That meant dragging the audio test equipment out and running a full sweep of tones through the entire transmission system, usually late at night.  It was a great pain, however, it was also a good exercise in basic physics.  Understanding pre-emphasis and de-emphasis curves, how an STL system can add distortion and overshoot, how clean (distortion wise) the output of the console is, how clean the transmitter modulator is, how to correct for base frequency tilt and high frequency ringing, all of those are basic tenants of broadcast engineering.  Mostly today, those things are taken for granted or ignored.

Audio frequency vs. wavelength chart

Audio frequency vs. wavelength chart

Every ear is different and responds to sound slightly differently.  The frequencies and SPL’s given here are averages, some people have hearing that can go far above or below average, however, they are an anomaly.

An understanding audio is a good start.  Audio is also known as sound pressure waves.  A speaker system generates areas or waves of lower and high pressure in the atmosphere.  The size of these waves depends on the frequency of vibration and the energy behind the vibrations.  Like radio, audio travels in a wave outward from it’s source, decreasing in density as a function of area covered.  It is a logarithmic decay.

The human ear is optimized for hearing in the mid range band around 3 KHz, slightly higher for women and lower for men.  This is because the ear canal is a 1/4 wave length resonant at those frequencies.  Mid range is most associated with the human voice and the perceived loudness of program material.

Base frequencies contain a lot of energy due to the longer wave lengths.  This energy is often transmitted into structural members without adding too much to the listening experience due to a sharp roll off starting around 100 Hz.  Too much base energy in radio programming can sap loudness by reducing the midrange and high frequency energy from the modulated product.

High frequencies offer directivity, as in left right stereo separation.  Too much high frequency sounds shrill and can adversely effect female listeners, as they are more sensitive to high end audio because of smaller ear canals and tympanic membranes.

Processing programming material is a highly subjective matter.  I am a minimalist, I think that too much processing is self defeating.  I have listened to a few radio stations that have given me a headache after 10 minutes or so.  Overly processed audio sounds splashy, contrived and fake with unnatural sounds and separation.  A good idea is to understand each station’s processing goals.  A hip-hop or CHR stations obviously is looking for something different than a clasical music station.

For the non-engineer, there are three main effects of processing;  equalization, compression (AKA gain reduction), expansion.  Then there are other things like phase rotation, pre-emphasis or de-emphasis, limiting, clipping and harmonics.

EQ is a matter of taste, although it can be used to overcome some non-uniformity in STL paths.  Compression is a way to bring up quite passages and increase the sound density or loudness.  Multi band compression is all the rage, it allows each of the four bands to react differently to program material, which can really make things sound differently then they were recorded. Miss adjusting a multi band compressor can make audio really sound bad.  Compression is dictated not only by the amount of gain reduction, but also by the ratio, attack and release times.  Limiting is a relative to compression, but acts only on the highest peaks.  A certain amount of limiting is good as it acts to keep programming levels constant.  Clipping is a last resort method for keeping errant peaks from effecting modulations levels.  Expansion is often used on microphones and is a poor substitute for a well built quite studio.  Expansion often adds swishing effects to microphones.

I may break down the effects of compression and EQ in a separate post.  The effects of odd and even order audio harmonics could easily fill a book.

Axiom


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution

Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin

The individual has always had to struggle to keep from being overwhelmed by the tribe. To be your own man is hard business. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.
~Rudyard Kipling

Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19

...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner

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