Vibratese
A tactile communication system using duration, intensity, and location.
Vibratese transmits information through tactile signals that vary in both duration and intensity. In 1957, F. A. Geldard built the first devices, which used five vibrating modules strapped to the wearer’s chest. Each module corresponded to a different part of the script, and the length and strength of its vibration indicated a specific symbol. The system was originally designed to send intelligence to military personnel in sensitive situations, though its potential to assist deaf and blind users was recognized even before Geldard’s first publication.
Geldard identified three tactile qualities that an interpreter could distinguish quickly: how long a vibration lasted, how strong it was, and where it occurred. Morse code, by contrast, relies only on duration and can be adapted for touch. By using all three dimensions instead of just one, Geldard achieved faster information transfer. Various layouts were considered, including a seven-point configuration, but five modules proved adequate. He settled on three possible durations—100, 300, and 500 milliseconds—and three intensity levels per vibrator, which allowed for 45 distinct symbols. Individual symbols were separated by 50 milliseconds, with a 100-millisecond pause between words. This setup gave a theoretical top speed of 67 words per minute, compared to roughly 30 for Morse code.
To avoid confusion, each vowel was assigned its own vibrating module. Numerals took the longest duration signals, and the remaining letters were assigned based on how often they appear in English. Some symbol slots were reserved for common whole words. The system faced problems, however. Training required about 30 lessons, each roughly an hour, which was considered too long. There was also ambiguity along the short-duration and intensity axes. One proposed fix was to add another time duration while reducing the number of intensity levels. Geldard also suggested a different design using closely spaced vibrators to create focal movements, like a finger tracing a pattern on the skin, which could function similarly to a Lorm alphabet.
- Developer
- F. A. Geldard
- Year of development
- 1957
- Number of vibrating modules
- 5
- Signal durations
- 100 ms, 300 ms, 500 ms
- Number of intensity levels
- 3
- Total encodable symbols
- 45
- Theoretical maximum transmission rate
- 67 words per minute
Lore & Background
Vibratese was first developed by F. A. Geldard in 1957 using five vibrating modules attached to the interpreter's chest. Each vibrator corresponded to a different segment of the script, and the duration and intensity of the vibration indicated a particular symbol. Geldard identified three tactile dimensions that could be easily and quickly discerned: duration, intensity, and location. He found that using all three dimensions allowed for higher information transmission rates than systems relying on duration alone, such as Morse code. Several device configurations were considered, including a seven-point arrangement, but five modules were deemed sufficient. The system used three durations (100 ms, 300 ms, 500 ms) and three intensities per vibrator, yielding 45 possible symbols. Individual symbols were spaced 50 ms apart, with a 100 ms pause between words, giving a theoretical maximum transmission rate of 67 words per minute, compared to about 30 for Morse code. To prevent ambiguity, each vowel character was assigned to a separate vibrating module. Numerals were assigned to the longest duration signals, and the remaining letters were assigned according to frequency. Several symbol slots were also assigned to common English words.
Reader's Guide
Vibratese was initially developed as a potential avenue to transmit intelligence to military targets in compromising environments. Although not mentioned in Geldard's first paper, its potential application for the deaf and visually impaired was understood. Several issues were identified with the system. The amount of training time required was seen as excessive—30 lessons, equated as hours, were needed to learn the system. Additionally, ambiguity along the short-time intensity axis was a problem. A proposed solution was to add an additional time duration while decreasing the intensity axis. Geldard also proposed a potential system using closely spaced vibrators that could transmit focal movements, like the tracing of a finger, on the subject, which could be used like a Lorm alphabet. The system's significance lies in its demonstration that multi-dimensional tactile coding could theoretically outperform single-dimension codes, though practical adoption was limited by training demands and perceptual ambiguities.
Did You Know?
- The system encoded 45 symbols using three durations and three intensities per vibrator.
- Its theoretical maximum transmission rate was 67 words per minute, more than double Morse code's 30 words per minute.
- Geldard proposed a variant using closely spaced vibrators to transmit focal movements, similar to a Lorm alphabet.
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