Browse Prior Art Database

Multiple Track Rotating Head for Speech Compression

IP.com Disclosure Number: IPCOM000085690D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 47K

Publishing Venue

IBM

Related People

Enger, A: AUTHOR

Abstract

A mechanism for speeding and slowing recorded speech, independent of pitch changes, has been described in the literature. Described is a mechanism in which an expensive custom-made playback head is avoided by use of "off-the-shelf" common parts.

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Multiple Track Rotating Head for Speech Compression

A mechanism for speeding and slowing recorded speech, independent of pitch changes, has been described in the literature. Described is a mechanism in which an expensive custom-made playback head is avoided by use of "off-the- shelf" common parts.

If a tape has been recorded on a conventional tape recorder, and played on a conventional tape player at the original speed, the original pitch and speech rate will be reproduced. It has been shown that rate is a function of the speed of the tape through the machine, and that pitch is a function of the speed of the tape with respect to the gap of the playback head. The two speech features function separately in a player where tape-to-machine and tape-to-head speeds are not intimately related.

Existing speeded-speech players provide a rotating tape head with four gaps spaced 90 degrees apart around a rotating cylinder. The tape is in contact with the cylinder for 90 degrees and is therefore always in contact with exactly one gap. Tape travels through the machine at the tape-to-machine speed for the desired speech rate. The head rotates in one direction or the other in order to maintain the proper tape-to-head (gap) speed for the desired pitch.

Shown in Fig. 1 is a mechanism in which multiple tracks on the tape are recorded with the same audio signals staggered as shown. Each head records one track. In the example, quarter-track recording is used. For playback, as shown in Fig. 2, multiple-track playback heads are arranged on a cylinder and a switching mechanism samples each track of each head in succession. The effect is identical to that of existing machines. A larger diameter cylinder can be used for a given tape speed. This gives enough room to use standard tape heads.

Existing machines which utilize a rotating cylinder with tape head gaps situated around its circumfere...