|Fig. 1. While recording this tamtam, the author wrapped the mic in a towel and coiled the cable to minimize handling noise.|
MICROPHONES ALLOW us to hear and record
sounds that are otherwise imperceptible to
the naked ear. Just as a doctor uses a stethoscope
to listen to a patient’s cardiopulmonary
system, a recording engineer can use a mic to
explore an instrument for unique sounds.
The vibrating body of an instrument produces
numerous localized spectral components
that can only be heard when a listening
device is in very close proximity. By focusing
on specific areas, we can capture unusual harmonic
combinations that change over time,
and enhance the effect by moving the microphone
by hand while we record. In this article,
I will explore this idea using cymbals and
gongs, which offer harmonically rich timbres
that are fun to work with.
Good Vibrations An instrument’s timbre is
defined by the resonating characteristics of the
materials from which it is built. The 19th-century
physicist Ernst Chladni demonstrated the
vibrational modes of solid surfaces by bowing
the edge of a metal plate that was covered in
a fine layer of sand. As the surface resonated,
the sand formed into patterns that showed
the positions of the nodes and anti-nodes at a
specific resonating frequency. Search for the
term “Chladni” on YouTube and you’ll find
videos that demonstrate this phenomenon
and give you some insight into why you’ll
hear different sounds as you move a mic over
a vibrating surface.
The definitive example of this miking
technique is Karlheinz Stockhausen’s classic
work Mikrophonie I for tam-tam (a type of
gong with a flat center) and six musicians.
(Two musicians play the instrument, two move
microphones, and two process the sounds in
real time.) The impetus for the work came
when Stockhausen used household objects
to play a large tam-tam he had acquired.
While he scraped and tapped the instrument,
he moved a handheld microphone
over the surface to pick up the complex
resonances being produced, while a colleague
filtered and recorded the sounds that
the microphone captured. Although the
initial experiment was improvised, Stockhausen
went on to compose a piece that utilizes
metal, wood, rubber, glass, cardboard,
and plastic to excite the tam-tam’s surface,
ranking the types of sounds created from
low and dark to high and bright. The technique
can be performed on just about any
object that resonates, and the method used
to excite the instrument plays a role in the
sounds you’ll hear.
Close Miking Although the attack of various
materials and playing techniques are interesting,
an instrument’s decay characteristics can
be just as fruitful. The trick is to move the mic
in as close as possible to the cymbal or gong
as the vibration decreases. Your ear will guide
you to the right spots if you monitor the mic
input through headphones.
Any microphone that is easy to hold and
move can be used. The main thing to avoid is
handling noise, which is generated at the mic
or by cable movement. You may have to wrap
the mic body in something that mitigates the
noise, such as a towel or soft foam (see Figure 1).
You should also coil up a portion of the cable
in your hand so that the cable doesn’t scrape
Mic type and polar pattern play a major
role in what you’ll hear. If the mic has a directional
pattern, you can focus more precisely
on interesting timbres. However, you will also
get an increase in lower frequencies due to the
proximity effect. If that bothers you, try using
an omni pattern.
Spend time finding the sweet spot on the
instrument. Each playing technique will excite
different vibrational modes in different parts
of a gong or cymbal. Don’t simply put the mic
over the area you’re playing. Try hitting the
edge of the gong and moving the mic around
the center of the instrument. Or tap the center
and move the mic slowly to the edge and
back again to exaggerate the timbral shifts the
instrument offers as it decays.
Explore Dynamics Typically, the harder
you hit a cymbal or gong with a wooden stick,
the higher the harmonics you’ll hear. As the
sound decays, the timbre gradually changes as
the higher harmonics fade. I often find the sustaining
portion to be as interesting as the attack,
and I look for ways to excite a tam-tam or
cymbal that help it sustain longer, such as using
soft yarn, rubber, or wool mallets. Hitting
it with a knuckle or closed fist can produce
darker tonalities that shift subtly.
You can elicit higher harmonics without
resorting to loud hits by tapping or scraping
the instrument gently with a blunt piece of
metal, such as a triangle beater or bolt. (Pick
something that doesn’t damage the instrument.)
Another technique is to place the open
end of a paper tube flat against a gong and
scrape it. When done correctly, it generates a
shriek that is rich with harmonics.
You can get a similar effect by dragging the
head of a drumstick flat against the surface of a
cymbal, or by using a violin or cello bow on the
edge. Pulling a superball, stuck to the end of a
chopstick, across the surface will produce a variety
of high-frequency tones, depending on how
hard you press down and how quickly you move.
Envelope Moving the microphone quickly
towards and away from the instrument helps
shape the envelope of the sound. The results
can be a tremolo effect that includes spectral
shifts, and the father away from the instrument
you go, the deeper the effect will be. You can
also move the mic toward a different spot each
time you get close to the cymbal.
My favorite envelope shape involves rushing
the mic towards the instrument immediately
after it’s struck, then gradually slowing
the mic movements as the instrument decays
(the opposite of the way a ball would bounce
off the ground). Non-linear, arrhythmic mic
moves yield the most interesting results,
though moving the mic in time with the beat
is also nice.
To exaggerate the decay or create a reverse
envelope, add a compressor in the signal path.
A high ratio and slow decay will further transform
Gino Robair writes about and teaches audio
recording in the Bay Area. Check out his
music at ginorobair.com.