The Intelligibility of Speech Transposed Downward in Frequency by One Octave

Thomas IB, Flavin FE. The Intelligibility of Speech Transposed Downward in Frequency by One Octave. J Audio Eng Soc. 1970;18(1):56-62. Available from: https://aes.org/publications/elibrary-page/?id=1525

@article{Thomas1970_1525,
  author = {Thomas, Ian B. and Flavin, Francis E.},
  title = {{The Intelligibility of Speech Transposed Downward in Frequency by One Octave}},
  journal = {Journal of the Audio Engineering Society},
  volume = {18},
  number = {1},
  pages = {56--62},
  year = {1970},
  month = feb,
  publisher = {Audio Engineering Society},
  url = {https://aes.org/publications/elibrary-page/?id=1525}
}

TY  - JOUR
TI  - The Intelligibility of Speech Transposed Downward in Frequency by One Octave
AU  - Thomas, Ian B.
AU  - Flavin, Francis E.
T2  - Journal of the Audio Engineering Society
J2  - J. Audio Eng. Soc.
VL  - 18
IS  - 1
SP  - 56
EP  - 62
PY  - 1970
DA  - 1970/02/06
UR  - https://aes.org/publications/elibrary-page/?id=1525
PB  - Audio Engineering Society
LA  - en
AB  - A method is described for transposing speech down by one octave in real time. Speech is filtered so as to suppress all formant components except the second formant and then clipped; the resulting signal is highly intelligible. Transposition to lower frequencies to accomplished by dividing this clipped signal by two, using a simple digital divide-by-two technique. A modulator is used to reimpose the envelope of the filtered speech onto the constant amplitude transposed signal. Finally, a lowpass filter is used to prevent high-frequency distortion products from reaching the output. Scores on listening tests after training average 77%. The potential use of such a device in aiding the partially deaf is discussed.
ER  -