At S.E.A. we keep searching for new improvements all the time, and keep on devising new ways of testing our equipment. This is how we find out whether our voice communication equipment really conveys spoken words in a practical way. (The test is the same for all voice communication equipment. In the pictures below, the SE400 speaker-box was used.)
Het, hit, hat, hut, hot...
We have devised a list of word pairs that we suspect might be difficult to differentiate. The reader then puts on a respirator and proceeds to read the words, holding up the speaker unit.
Huh? Oh, I get you.
In front of the speaker, the members of a test panel write down the words as they hear them.
Men's talk, women's talk.
Both men and women act as readers.
Hmm. Was that 'ten' or 'pen'? These two words often turn out to be the most difficult to distinguish, while word pairs like 'pub' and 'pig' seem easy to the test panel.
A noise meter in front of the reader is used to record the loudness of the speech, whether using an amplifier or speech diaphragm.
These tests give us valuable hints as to the design of the equipment. Already, we have achieved substantial improvements in the conveying of speech while wearing a respirator. Further improvements can be expected.