This device is the ancestor of the audio spectrum analyzers with spectrogram or visible speech: real-time display of the voice spectrum. Digital electronics with analog to digital conversion did not exist in 1946. Formants: spectral components of the voice are isolated by resonant electric filters. We see in fig. 6 the deformation of formants according to the context of appearance of vowels in certain English words. Speech understanding will be contextualized pattern recognition.
fig. 5 shows how formants are displayed using neon lights on a scrolling phosphor strip. The persistence of the image is erased by an infrared lamp so that the image is constantly renewed to the rhythm of the voice to be analysed. Already in 1946, we also knew how to display these images on a special cathode ray tube.
<a href="//commons.wikimedia.org/w/index.php?title=User:Fil22plm&amp;action=edit&amp;redlink=1" class="new" title="User:Fil22plm (page does not exist)">Fil22plm</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>