Handbook for Sound Engineers

556 Chapter 16

speakers are used to provide hearing signals forward of

the listener.

Fig. 16-140A shows an ETC made in a listening

room (LDLR= 0.24). Fig. 16-140B is the identical

position measured with the ITE technique

(LDLR= 5.54). Note particularly the difference in

LDLR for the two techniques. ITE recording and PAR

playback allow a given listener to hear a given speech

intelligibility environment as perceived by another

person’s head and outer ear configuration right up to the

eardrum.

Recordings made using ITE microphones in two

different people’s ears of the same performance in the
same seating area sound different. Playback over loud-

speakers where the system is properly balanced for

perfect geometry for one person may require as much as

10 dB different front to back balance for another person

to hear perfect geometry during playback.

Since ITE recordings are totally compatible with

normal stereophonic reproduction systems and can

provide superior fidelity in a many cases, the practical

use of ITE microphony would appear to be unlimited.

16.9 USB Microphones

The computer has become a important part of sound

systems. Many consoles are digital and microphones are

connected directly to them. Microphones are also

connected to computers through the USB input.

The audio-technica AT2020 USB cardioid condenser

microphone, Fig. 16-141 is designed for computer-

based recording. It includes a USB (Universal Serial

Bus) digital output that is Windows and Mac comp-

atible. The sample rate is 44.1 kHz with a bit depth of

Figure 16-139. The loudspeaker arrangement used for PAR
playback of ITE recordings. Courtesy Syn-Aud-Con.

5 ¾ 5 ¾

6 ¾^6 ¾

A. Top view

B. Side view

Figure 16-140. An ETC comparison of a measurement

microphone and the ITE technique at the same position in

the room. Courtesy Syn-Aud-Con.

Dir/Rev Energy 0.24 dB

Reverb(S) 0.17 s

Alcons 2.42%

RASTI 8.786

excellent

6 dB SNR > 4.39 dB

(^0) Time–Ms 49,869
A. An ETC made in a listening room with a GenRAd 1/2 inch
microphone (Lo LR = 0.24).
Dir/Rev Energy 5.54 dB
Reverb(S) 0.16 s
Alcons 2.26%
RASTI 0.798
execellent
6 dB SNR >^ 8.89 dB
(^0) Time - Ms
49,869
B. The identical position measured with the ITE
technique (LD LR = 0.24).