Handbook for Sound Engineers

578 Chapter 16

dard worldwide in TV. A Softy attenuates the wind
noise about 24 dB, Fig. 16-163B.

Adding a Windjammer (furry cover) to the basket
windshield will give an improvement of about 10 dB at
low frequency to 35 dB, Fig. 16-163C. The attenuation
of the Windjammer is approximately 5 dB at frequencies
above 6 kHz although this will increase if it is damp or
the fur is allowed to get matted. Overall this combination
gives the best performance of wideband wind noise
reduction against signal attenuation. To determine the
correct windscreen for microphones of various manufac-
turers, go to http://www.microphone-data.com.

Pop protection is best appreciated when close-talking
and explosive breath sounds are particularly bother-
some. These explosive breath sounds are commonly
produced when saying words involving P and T sounds.
The phrase explosive breath sound is somewhat of a
misnomer since these sounds, without amplification, are
normally inaudible to a listener.^15

The electrical output from the microphone is actually
the transient microphone response to this low-velocity,
high-pressure, pulse-type wavefront. The P and T
sounds are projected in different directions and can be
shown by saying the letters P and T while holding your
hand about 3 inches (7.6 cm) in front of your mouth.
Note that the T sound is felt at a considerable distance
below the P sound.

For most microphones, pop output varies with
distance between the source and microphone, reaching a
peak at about 3 inches (7.6 cm). Also the worst angle of
incidence for most microphones is about 45° to the
microphone and for a glancing contact just at the edge
of the microphone along a path parallel to the longitu-
dinal axis.

sE Dual Pro Pop Filter. An interesting pop filter is
shown in Fig. 16-166. The sE Dual Pro Pop pop screen
is a two-filter device to suit vocal performances. The
device has a strong gooseneck with both a standard
fabric membrane and a pro metal pop shield on a hinge
mechanism. They can be used separately or both simul-
taneously depending on the application.

In an emergency pop filters can be as simple as two
wire-mesh screens treated with flocking material to
create an acoustic resistance.

16.12.2.2 Reflexion Filter

The Reflexion Filter by sE Electonics is used to isolate
a microphone from room noises hitting it from
unwanted directions, Fig. 16-167.

The reflexion filter has six main layers. The first

layer is punched aluminum, which diffuses the sound

waves as they pass through it to a layer of absorptive

wool. The sound waves next hit a layer of aluminum

foil, which helps dissipate energy and break up the

lower frequency waveforms. From there they hit an air

space kept open by rods passing through the various

layers.

Next the waves hit an air space that acts as an

acoustic barrier. The sound waves pass to another layer

of wool and then through an outer, punched, aluminum

wall that further serves to absorb and then diffuse the

remaining acoustic energy.

The various layers both absorb and diffuse the sound

waves hitting them, so progressively less of the original

source acoustic energy passes through each layer,

reducing the amount of energy hitting surfaces so less of

the original source is reflected back as unwanted room

ambience to the microphone. The Reflexion Filter also

reduces reflected sound from reaching the back and

sides of the microphone. The system only changes the

microphone output by a maximum of 1 dB, mostly

below 500 Hz.

The stand assembly comprises a mic stand clamp

fitting, which attachs to both the Reflexion Filter and

any standard fitting shock mount.

16.12.3 Shock Mounts

Shock mounts are used to eliminate noise from being

transmitted to the microphone, usually from the floor or

table.

Microphones are very much like an accelerometer in

detecting vibrations hitting the microphone case. Shock

Figure 16-166. sE Dual Pro Pop pop screen. Courtesy sE

Electronics.