Inside Audio: Dave Moulton
TV Audio: Good Is Not Good Enough
Two months ago we ranted about bad audio, goaded
on by reader Bro Duke, who wants the FCC to DO SOMETHING about it!
Well, we got a fair amount of mail, with some interesting horror
stories.
Gary Davis, who has written for TV Technology, wrote
to point out that in the televised concert on Sept. 21 – dedicated
to the victims of Sept. 11 – the stereo was reversed on feeds
in New York and Los Angeles, although he noted that in London it
was correct.
Reader George Bell speculated that some of the rebroadcast
stuff I described sounded like undecoded Dolby C. He also described
a technique used by some engineers to keep levels down at transmission
by recording a 17 Hz tone up around 0 VU (your basic slate tone),
mixed with the program. Of course, any heavy limiter (how do you
spell Optimod?) will turn this program down to whatever level the
threshold is set – audio police or vandals?
Bro Duke also wrote in to relate the sad tale of
a badly overmodulated commercial production produced while monitoring
on a cheap 12-inch woofer housed only in the cardboard box it was
shipped in.
Sheesh!
SURVEY SAYS
At the same time, I did an informal survey of the
audio for TV practices I encounter on my television (which has a
"digital" cable feed with about 150 channels). And these
days I'm watching/listening on a REALLY GOOD TV with excellent broadband
audio configured in stereo, equivalent to a really decent home audio
system.
By and large, I'm happy to report, the TV audio wasn't
too bad. Nonetheless, there are bad spots and some of them seem
endemic. One channel has had a loud (-15 dB?!) 60 Hz hum for about
eight months.
The local access channels all have miserable audio,
with massive distortion and varying amounts of hum and buzz. (It
is bad enough that with 10 minutes' practice you can easily identify
any given channel by its particular brand of lousy sound quality.)
More embarrassing to us pros, one major channel that
broadcasts NFL football has a serious problem with stereo compatibility,
summing an array of crowd signals with varying delay to mono. This,
of course, yields massive and blatant comb filtering that simply
destroys any entertainment quality the broadcast might have had.
("Martha! What's that danged howling noise? It's doing it again!")
But these are, by and large, isolated instances.
Mostly, TV audio (and I am referring mainly to the voice-plus-bed
quality of live news, talk and entertainment programming) is clean,
intelligible and has decent frequency response.
HEARING VOICES
However, a particular "style" of audio
has emerged for voice production on TV. It has evolved as a function
of the desire to have multiple isolated sources (I'm talking about
voices here) emitting from the same acoustic space. Lavalier mics,
because of their inconspicuous nature, have become the mics of choice
for this task. Naturally, their placement is less than ideal, as
is their directionality.
This leads to, er, enhancement (high-frequency EQ
boost, mainly), which in turn leads to other local noises and HF
leakage from other sound sources in the room. Some gating is done,
and the general effort seems to be to reduce interference artifacts
as much as possible.
This is all swell, in theory. In reality, voices
are bone dry, very bright and edgy (what the audiophile guys call
"spitty" and "sssibilant"), and often a vaguely
sour-sounding low-level comb filtering in the "sssibilance"
due to crosstalk with other sources that have their own open lavaliers
trying to do the same thing.
This is quite a peculiar production style thing that
now is how "TV sounds." Keep in mind, this is not how
reality sounds. There is no longer any room tone on TV, no stereo
ambience surrounding the voices, no sense of place, depth or context.
Talking heads are flat, in front, in your face and "spitty."
Is this good or bad? I don't know. It doesn't seem
very pleasant. What I do know is that, when you listen carefully
and objectively to it, it does sound a little weird and definitely
unnatural.
FIXING THINGS
Is there anything we can do to make things better?
The answer is, of course, yes.
The obvious stuff that would solve the problems would
be more meticulous attention to the implications and limitations
of stereophony, better documentation and more attention paid to
said documentation, less audio vandalism on the one hand and more
restraint in the use of final-stage signal processing chains on
the other and – most important – better monitors and monitoring
environments.
In addition, restraint, care and thoughtfulness in
terms of the following topics would help.
Microphone Handling
Maybe a lavalier isn't always the best way to go.
It may be possible to use a much better microphone, placed better
for human voice. There are some awfully good microphones out there,
with some very interesting capabilities. Lavaliers may be quick
and convenient – however, there may be more to life than just
quick and convenient.
EQ
Stuffing in a 6-10 dB peak at 4.5 kHz in order to
emphasize the consonants for intelligibility – in a room with
multiple sound sources – is not necessarily a good idea. Once
again, strategies for better placement and better microphones may
reduce the need for "induced edge."
Levels' Management
Companders are both seductive and deadly, particularly
when we layer them (and we do, come on, admit it!). Less can be
more – so lighten up on the ratio, the threshold and the release
time, and don't put a heavy limiter with a low threshold in line
with a really stiff noise gate at a high threshold. Instead, get
better levels at the mic, working in a quieter studio.
Stereo and Surround
These can be your friends, if you can get a handle
on how they work. The big secret weapon here is ambience, the short-term
room tone and early reflections that aren't perceived directly.
Unfortunately, right now "ambience" is OUT on TV, except
for the occasional crowd roar and car drive-by at televised stock
car racing events, and other similarly ambience-laden sporting activities.
Critical Listening
The real secret to audio quality, of course, lies
in critical listening. Critical listening is the intense and careful
analysis of how recorded sound works, what sounds good, what sounds
bad and why, what can be improved, and what can't. TV sound faces
more than its fair share of problems in this regard. The visual
requirements of the medium, combined with intense time and financial
pressures, all mitigate against the meticulous effort needed to
manage really good audio.
For the time being, TV audio is acceptable, generally,
which is to say that you can understand the words, distortion is
modest, and the noise floors and tone quality aren't too bad. Bro
Duke's examples reveal the bottom feeders, maybe even the bottom
quartile, of the system, I suspect. Mostly, production is better
than those wretched cases (and, yes, I stayed up to watch Leno,
Letterman and Maher to satisfy myself in this regard).
But acceptable isn't the same as good, and good isn't,
to revisit Bob Dixon of NBC for a moment, good enough! And yes,
we CAN hear the difference.
Thanks for listening.
Dave Moulton is hard at work on some wild new music!
You can complain to him about this or anything else at www.moultonlabs.com.
© 2002 by David Moulton
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