Handbook for Sound Engineers

Microphones 527

of peaks and dips that decrease in amplitude with

frequency.

• The edge-wave interference decreases if the incoming
  sound waves approach the boundary at an angle.


• Interference also is reduced by placing the micro-
  phone capsule off-center. This randomizes the
  distances from the edges to the microphone capsule,
  resulting in a smoother response.

16.6.2 Lavalier Microphones

Lavalier microphones are made either to wear on a lava-
lier around the neck or to clip onto a tie, shirt, or other
piece of clothing. The older heavy style lavalier micro-
phone, Fig. 16-72, which actually laid on the chest, had
a frequency response that was shaped to reduce the
boomingness of the chest cavity, and the loss of
high-frequency response caused by being 90° off axis to
the signal, Fig. 16-73. These microphones should not be
used for anything except as a lavalier microphone.

Lavalier microphones may be dynamic, condenser
(capacitor), pressure-zone, electret, or high-impedance
ceramic.

The newer loss mass clip-on lavalier microphones,
Figs. 16-74 and 16-75, do not require frequency
response correction because there is no coupling to the
chest cavity and the small diameter of the diaphragm
does not create pressure build-up at high frequencies,
creating directionality.

Most lavalier microphones are omnidirectional,

however, more manufacturers are producing directional

lavalier microphones. The Sennheiser MKE 104 clip-on

lavalier microphone, Fig. 16-74, has a cardioid pickup

pattern, Fig. 16-76. This reduces feedback, background

noise, and comb filtering caused by the canceling

between the direct sound waves and sound waves that

hit the microphone on a reflective path from the floor,

lectern, and so forth.

One of the smallest microphones is the Countryman

B6, Fig. 16-77. The B6 microphone has a diameter of

0.1 inches and has replaceable protective caps. Because

of its small size, it can be hidden even when it’s in plain

sight. By choosing a color cap to match the environ-

ment, the microphone can be pushed through a button

hole or placed in the hair.

Lavalier microphones are normally used to give the

talker freedom of movement. This causes problems

associated with motion—for instance, noise being trans-

mitted through the microphone cable. To reduce this

noise, soft, flexible microphone cable with good fill to

reduce wire movement should be used (see Chapter 14).

The cable, or power supply for electret/condenser

microphones, should be clipped to the user’s belt or

pants to reduce cable noise to only that created between

the clip and the microphone, about 2 ft (0.6 m). Clip-

Figure 16-72. Shure SM11 dynamic omnidirectional lava-

lier microphone. Courtesy Shure Incorporated.

Figure 16-73. Typical frequency response of a heavy-style

dynamic lavalier microphone.

+10

0

10

(^20) 20 50 100 1K 10K 20K
Relative response–dB Frequency–Hz
Figure 16-74. Shure SM183 omnidirectional condenser
lavalier microphone. Courtesy Shure Incorporated.
Figure 16-75. Sennheiser MKE 104 lavalier clip-on direc-
tional microphone. Courtesy Sennheiser Electronic Corpo-
ration.