Precise perceptibility of the original loudness of a speaker through electro-acoustic playback

Experiments were undertaken in which the test persons compared the playback loudness of electrically reproduced signals with the original loudness. For this purpose speech recordings were made in different rooms. Sometimes the speaker was known to the research workers, at other times he was unknown. The work showed that the original loudness in an approximately 2 dB range level is reproduced the mean value for an unknown speaker being a little less than the original loudness. Moreover with the help of a spectrum level analyser the spectral differences of various loud speakers may be determined.