Some Further Experiments upon the Recognition of Speech, with One and with Two Ears

The experiments described here continue a series reported in this Journal earlier. A number of objective tests are described, directed towards the general problem concerning the faculty we possess of perceiving only one acoustic world under normal conditions (in spite of having two ears) and yet, if our ears be stimulated by different signals, artificially, we can attend to one or the other of them. The tests have been made with continuous speech (readings from light fiction) and the results assessed statistically. The first tests aim at measuring the reaction time r required to “switch the attention” from one ear to the other, as assessed by perception of the words of the message. A second set of tests show that we perceive only one speaker, as a “gestalt,” when the ears are stimulated by similar messages but with a delay between them exceeding 20 times that ever experienced in real life by virtue of binaural directivity.