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BELL SYSTEM TECHNICAL JOURNAL 



type receiver bridged across the mid-point of an attenuator tying the 

 two channels together. The attenuation used in the monitoring cir- 

 cuit was such as to give no audible feed-back in either booth. The 

 results obtained with this set-up were considered satisfactory from the 

 standpoint of both volume and quality. Ready recognition of familiar 



Fig- 1 — Microphone and loud speaker in position above and below television scanning 



and viewing aperture. 



voices and the association of the source of the reproduced sounds with 

 the image were the usual occurrence. Figure 2 shows in block form 

 the complete circuit set-up and Figure 3 shows the combined response 

 frequency characteristic of the microphone, amplifier and loud speaker. 



