Tadoma

Tadoma. It is a tactile communication method used by some individuals who are deafblind to perceive speech. The user places a hand on the face and neck of a speaker to feel the vibrations, movements, and airflow associated with spoken language. This technique allows for the direct reception of spoken communication without the use of intermediary devices or visual cues. It is named after the first two students, Tad Chapman and Oma Simpson, who were formally taught the method at the Perkins School for the Blind.

Overview

Tadoma is a specialized form of speechreading that relies entirely on the sense of touch. Practitioners, often called Tadoma users or tactual speechreaders, monitor the complex physical dynamics of speech production. This includes detecting the articulatory movements of the jaw, lips, and tongue, as well as the nasalization of sounds and the timing of vibration from the larynx. The method is primarily associated with the education of individuals who are deafblind, particularly following the work of Sophie Alcorn and others at the Perkins School for the Blind in Watertown, Massachusetts. While technologically simple, it demands significant skill and concentration from both the user and the speaker.

Method and technique

The standard technique involves the user placing their thumb lightly on the speaker’s lips, with fingers spread along the jawline and the pinky finger sensing vibrations on the throat. This hand position allows for the simultaneous detection of multiple speech parameters. The user feels the bilabial movements for sounds like /p/ and /m/, the fricative airflow for /s/ and /f/, and the glottal vibration for voiced consonants and vowels. Speakers must articulate clearly, often at a slightly slower pace, and avoid extraneous movements like chewing or turning the head. Mastery requires extensive training to interpret the subtle tactile patterns into recognizable words and prosodic features.

History and development

The method was systematically developed in the 1920s at the Perkins School for the Blind by educator Sophie Alcorn. It was named for her first two students, Tad Chapman and Oma Simpson. Alcorn's work built upon earlier observations of deafblind individuals, such as Laura Bridgman and Helen Keller, who naturally used touch to understand speech. Throughout the mid-20th century, Tadoma was a primary instructional method at Perkins and influenced programs at institutions like the Helen Keller National Center. Research into the method expanded at places like the Massachusetts Institute of Technology and the University of California, Berkeley, where scientists studied its psychophysics and informational limits.

Applications and users

Tadoma has been used by a small number of individuals worldwide, most notably some graduates of the Perkins School for the Blind. Prominent users included Robert Smithdas, a noted poet and advocate, and Richard Kinney, a former president of the American Association of the Deaf-Blind. Its application is almost exclusively for individuals with acquired or congenital deafblindness, for whom American Sign Language may not be accessible without sight. It is sometimes used in conjunction with other methods like the Manual Alphabet or Braille. The method requires a consistent communication partner, limiting its use in group settings or with unfamiliar speakers.

Effectiveness and limitations

With extensive practice, proficient users can achieve high levels of comprehension, understanding conversational speech in real-time. Research from the Massachusetts Institute of Technology has shown that some expert users can identify words with accuracy comparable to visual speechreading. However, the method has significant limitations. It requires physical contact, which can be socially intrusive or impractical. Comprehension can be hampered by speakers with beards, accents, or fast speech rates. The learning process is extremely lengthy and demanding, and the method is generally ineffective for perceiving environmental sounds or communicating with multiple people simultaneously.

Relationship to other communication methods

Tadoma exists within a broader ecosystem of deafblind communication techniques. It is distinct from Manualism, which uses a tactile sign language like Protactile or a visual-manual system adapted for touch, such as the Manual Alphabet spelled into the hand. It is also different from technological aids like hearing aids or cochlear implants. Tadoma is most closely related to speechreading, but substitutes touch for vision. Some users combine Tadoma with fingerspelling or use it as a bridge to develop language before learning American Sign Language. The development of Tadoma also inspired research into electromechanical sensory substitution devices, such as the Tactaid vibratory system.