Helping the blind 'see' with music

Researchers at the Hebrew University of Jerusalem have developed a new device that converts images into music to help individuals without vision reach for objects in space.

Sensory substitution devices (SSDs) use sound or touch to help the visually impaired perceive the visual scene surrounding them. The ideal SSD would assist not only in sensing the environment but also in performing daily activities based on this input. For example, accurately reaching for a coffee cup, or shaking a friend’s hand.

In a new study, Hebrew scientists trained blindfolded sighted participants to perform fast and accurate movements using their new SSD, called EyeMusic.

The EyeMusic employs pleasant musical tones and scales to help the visually impaired “see” using music. This non-invasive SSD converts images into a combination of musical notes, or “soundscapes.”

 The device was developed by the senior author Prof. Amir Amedi and his team at the Edmond and Lily Safra Center for Brain Sciences (ELSC) and the Institute for Medical Research Israel-Canada at the Hebrew University.

The EyeMusic scans an image and represents pixels at high vertical locations as high-pitched musical notes and low vertical locations as low-pitched notes according to a musical scale that will sound pleasant in many possible combinations.

The image is scanned continuously, from left to right, and an auditory cue is used to mark the start of the scan. The horizontal location of a pixel is indicated by the timing of the musical notes relative to the cue (the later it is sounded after the cue, the farther it is to the right), and the brightness is encoded by the loudness of the sound.

 The EyeMusic’s algorithm uses different musical instruments for each of the five colours: white (vocals), blue (trumpet), red (reggae organ), green (synthesized reed), yellow (violin); Black is represented by silence.

Prof. Amedi said “The notes played span five octaves and were carefully chosen by musicians to create a pleasant experience for the users.”

“We demonstrated in this study that the EyeMusic, which employs pleasant musical scales to convey visual information, can be used after a short training period (in some cases, less than half an hour) to guide movements, similar to movements guided visually,” explained lead investigators Drs. Shelly Levy-Tzedek, an ELSC researcher at the Faculty of Medicine, Hebrew University, Jerusalem, and Prof. Amir Amedi.

“The level of accuracy reached in our study indicates that performing daily tasks with an SSD is feasible, and indicates a potential for rehabilitative use,” they added.

The study lends support to the hypothesis that representation of space in the brain may not be dependent on the modality with which the spatial information is received, and that very little training is required to create a representation of space without vision, using sounds to guide fast and accurate movements.