Audio

A few entire courses or CD-roms could easily be included on the topic of audio. This course can only touch on the topic. The most serious issue in audio around the average TV station centres around monitoring and levels. While these have always been issues, as we invent new ways of monitoring, and new ways of recording and editing, these "issues" are rapidly becoming "disasters".

Until about 1995, as you watched television at home, all audio levels were similar.... programs, commercials, and the different channels (commercials always sounded a little louder because the had "fuller" soundtracks). Now, it is necessary to "watch" television with the volume remote in one hand! The breaks are too loud, and the programs too soft. The different stations all have different levels, and quality. What happened? We all stopped using the same tools to monitor audio. Also, once a program has been digitized to feed into a server, there are no downstream adjustments that can correct audio levels.

Our need for correct levels goes beyond smoothing things out for the viewer. If levels are too high, some piece of equipment will "clip" the peaks, causing distortion. If the levels are low enough that they need amplifying downstream, all of the hum, hiss, and other junk will be increased along with the audio that we want to hear.

	Here's how we should be monitoring audio: This is audio fed into a waveform monitor. If we calibrated this, we would be able to see exactly what our audio levels were. Alas, this is expensive enough that it's not going to happen.
	Here's how we DO monitor audio. Meters apply the alternating audio voltage to an electromagnet that pulls against a spring (actually, it's a small rotating assembly that's a cross between a motor, and a watch's mainspring). There used to be strict standards that defined the "ballistics" of the movement (spring tension, needle mass, etc.) but these standards have been "flung down and danced upon".
Beatles "Taxman" Guitar lead "Sixteen Tons" Tennessee Ernie Ford	Here is the problem with monitoring with mechanical meters: The two waveforms at the left are at the same electrical level. The upper waveform will deflect the meter more, due to it's constant energy. The lower waveform contains lots of "downtime" that lets the needle ride low. Devices that use VU meters need lots of "headroom"... because the meters can't respond to fast peaks of the waveform. This means that there is somewhere around 10db of space above "0", where the audio is not clipped.
Range: -23 +3 Yellow: -1 to 0 Red: Above zero	Meters that use flashing lights to indicate levels don't have a "ballistics" problem, but most manufactures have chosen to simulate mechanical meter ballistics... Arrrggghhh!
Range: -30 +22 Yellow:+7 to +10 Red: +22	This is a Mackie Mixer display. Compare to the above Furman display and note the difference in what the colours of the leds mean. Both of these displays are in the same edit room (!) as are the two below.
Range: -18 +5 Yellow: 0 to +4 Red: +4	This is a Digital Audio Workstation in the same edit room. The problem with all of these different designs, is that we don't read the actual numbers on the displays... we just tend to look at the position and colours of the indicators.
Range: Infinity to 0 Yellow: -12 to -6 Red: what red?	Adobe Premier's meters are in a class of their own. To compound the problem, the waveform tracks on Premiere's timeline used to "scale up" the audio image to fit the track. no matter how low the audio was. This has been fixed by version 6.5

Gone are the days when we could just set tone to "0" and be done with it. Our fancy indicating devices all react differently to program audio, but the same to tone! The difference is in the steady nature of tone.... the meters respond differently to dynamics, due to their different ballistics. Look again at the Furman... the editor has placed an orange reference dot to where tone should be set to get the indication of program audio correct.

"A person with one watch knows what time it is, a person with two watches is never sure."

What have we learned? Know your indicating device, and what it is telling you about your levels. The situation would be better if we could at least trust our ears, but the way that most monitoring is set up, we can't.

Plan "A"

Here is (was?) the classic way to monitor audio. The mixer feeds the recorder, which feeds the monitor. In STOP mode, the recorder passes the mixer's audio ("E-E" mode).

A Properly aligned recorder presents the same level in E-E as it does in playback.

Plan "B"

Here's the usual way of monitoring audio... the mixer feeds the monitor, and the recording machine's audio playback comes back through the mixer.

This makes it necessary to pull the recorder's level down during recording, and to "turn it up" to play back your work.

Too make matters worse, there are level controls on the monitor amplifier. With so many places to adjust what we hear in the edit room (server ingest room, etc), and "iffy" meters, well, we watch television with the volume remote in one hand!

Balance your world, at least. Keep a professionally mastered CD that you like on hand... preferably music with a well-mixed vocal. Before a session, play the CD through the mixer, with the mixer meters indicating full level (we all have slightly different ideas about that, but set it to your custom). Adjust the monitors to a comfortable listening level, taking you seating position into account (adjust left-right balance if necessary). Do not ever touch the monitoring levels again!

You also should insure that the recording device is indicating a good level, and that playing back a recording of your reference CD results in the same level.

None of this eliminates the necessity of setting levels with tone, but it will allow you to make pleasing sounding mixes with diverse audio content.

... if you have an Non-Linear Editor. In most situations, the audio card in the NLE is treated just like a record machine.... mixer to audio input and audio output to monitor... but the "E-E" function while not capturing may work, may not work, or may not be the same level. As a result, Plan "B" is used.... like the second layout above, where the NLE's output comes back through the mixer, and the audio you feed to capture is monitored before it gets to the recorder (NLE). In this case, you can only guess what you are doing. What could be worse? Well, some NLE's involve the Windows™ Soundcard. Have a Look at the Windows™ Soundcard simplified diagram.

One NLE passes the output of its card to the input of the Windows™ soundcard, and hooks the monitor speakers to the output of the Windows™ soundcard... only so that the operating system beeps can be heard. It would be better to buy some cheap speakers for the beeps, and eliminate the Windows™ soundcard from the path.