Reflections on sight loss - RNIB

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Spanish team shows
potential of echolocation
A team of researchers from the University of
Alcalá de Henares (UAH) in Madrid has shown
that human beings can develop echolocation.
The team has been researching the use of
tongue clicks to help people identify objects
around them without needing to see them –
the system used by American mobility expert
Daniel Kish (see NB, May 2009).
The team, led by Juan Antonio Martínez of the
Superior Polytechnic School of the UAH, has
begun a series of tests, starting with the
physical properties of various sounds. “The
almost ideal sound is the ‘palate click’, made
by placing the tip of the tongue on the palate,
just behind the teeth, and moving it quickly
backwards”, Martínez explains. “These clicks
are very similar to the sounds made by
dolphins, although on a different scale, as
these animals have specially adapted organs
and can produce 200 clicks per second, while
we can only produce
three or four.” Using
echolocation it is
possible to measure
the distance of an
object based on the
time taken to hear
the echo.
The scientists are working on a method to
teach people how to emit, receive and interpret
sounds. They say that no special physical skills
are required. “Two hours per day for a couple
of weeks are enough to distinguish whether
you have an object in front of you, and within
another two weeks you can tell the difference
between trees and a pavement”, says Martínez.
References
Martínez Rojas, Juan Antonio; Alpuente
Hermosilla, Jesús; López Espí, Pablo Luis;
Sánchez Montero; Rocío (2009): Physical
analysis of several organic signals for human
echolocation: Oral vacuum pulses. Acta
Acustica united with Acustica, 95 (2): 325-330.
New guidelines on eye care for deaf children
Eye care professionals are being urged to
ensure that deaf children’s needs are not
overlooked. Forty per cent of children who
are born deaf also have eye problems. A new
set of guidelines has been produced to help
professionals who work in vision and hearing
ensure that deaf children receive good vision
care. ‘Quality standards in vision care for
deaf children and young people: Guidelines
for professionals’ has been produced by
Sense, the national charity for deafblind
people, with the National Deaf Children’s
Society (NDCS).
Good vision is especially important to deaf
children, so it is important that problems are
identified early. The guidelines aim to
promote good practice in eye care for deaf
children and contain recommendations on
identifying vision difficulties, assessing a
deaf child’s vision, providing support and
involving the child and the family.
Links
➜ www.sense.org.uk/publicationslibrary/
allpubs/professionals/deafblindness/
vision_care_deaf_children.htm
www.sensehub.org.uk
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