User:Crazyteeth/sandbox/Optophone

Optophone is a seeing-aid device that scans text and then generates time-varying chords of tones to help the blind identify letters. The time-varying chords of tone is a system of coded sound like a rhythmed music. The variation of the amplitude, wavelength, rhythm and other traits of sound make different tone can carry different information. It works the similar way as bats’ echo-location system which helps them find their way around in the dark. Although optophone has nothing to do with the echo, both of them use sound information for very much the same kind of purpose as we use our visual information. Meanwhile, it is one of the earliest known applications of sonification which is the use of non-speech audio (the use of non-speech sounds such as whistling, humming or hissing ) to convey information of perceptualize data. The concept of Optophone was raised over 100 years ago and the first device was built in 1912 at the Optical Convention, held in the Science Museum at South Kensington. Initially, only a few units were built, and reading was exceedingly slow; a demonstration at the British Scientific Products Exhibition in 1918 involved Mary Jameson reading at one word per minute. Later models of the Optophone allowed speeds of up to 60 words per minute, though only handful people are able to achieve this rate. (Figure 4.)The reason why it is not used widely is that not only few people can achieve this rate to read and see fluently, but also there are few people can hear of the sound produced by the device.

Compared to the Braille, first of all, Optophone uses sound as the media transiting information. However, Braille uses  sense of finger as the media to transit information by touching different arrangements of dots. Secondly, Braille is not appropriate for the blind coming from other country speaking different language because it's based on different languages' characters or pronounces. On the contrary, Optophone is the device can make blind people "see" those real symbols, pictures and words in the book which is the same what normal people see so it does not have a limitation with different languages. In other words, Optophone is a device with certain language as a "bridge" leading to the real world. While, the Braille is a system of language based on local language so that blind can live more comfortably without "light". Lastly, the speed of Optophone is really slow, 60 words per minutes which might be the maximum rate of reading and few people can reach this speed. Nevertheless, Braille can efficiently transit information faster, running about 90 words per minute and most people can expertly can reach that speed. By the quickness and efficiency of braille, blind can even walk through the city with local system of Braille language like normal people do each day. The suitability and quickness lead to the wane of Optophone and adoption of the Braille in later one century.

History
The word “optophone” was invented by Dr. Edmund Fournier d'Albe as he was appointed Assistant Lecturer in Physics at the University of Birmingham in England in 1910. He set up a laboratory to study the properties of selenium. Since the discovery of selenium by Berzelius in 1817, the mystery of this new element faded away in the following years that the selenium was photosensitive. To be specific, its conductivity varies with the change of light.[1] In this way, people can transfer a certain picture into electric signals by the changing conductivity of selenium. This trait of selenium helps Edmund build a selenium detector and apply it on his first Optophone shown in the figure. 2. In 1912, his first Optophone, "Exploring Optophone" was successfully used by a blind at the Optical Convention, held in the Science Museum at South Kensington. Although this device received lots of good press coverage, it was criticized by Sir Wshington Ranger, a blind solicitor, who said :"The blind problem is not find lights of windows, but how to earn your living." As the results of this criticism Fournier d'Albe, invented a new Optophone, Reading Optophone which focus on aid of reading instead of mobility aid in 1913.

Mechanism
Generally, the Optophone uses selenium detector (a detector made by selenium which can perceive the change of light) to convert light in to sound, with the sound proportional to the intensity of the light falling on the detector. In this way, people can encode the process from the light to sound by a system of language with certain rule. Initially, the Optophone will scan across a line of text, with guidance from the useser, and produce a higher intensity sound for the lighter areas of the text, producing no sound for the black characters. The Optophone used a vertical row of five spots of light. When the light passed over the page, the reflection varied according to the character, or lack of character, scanned. The reflected light was detected by a row of selenium cells, which modulated the sound output, each spot of light producing a different musical note. However, this device has different ways to encode the visual information. The following is the development of different system encoding the process of converting information.

System Ⅰ, [Photocell System]
The first system of optophone uses 25 photocells arranged in a 5 by 5 pattern. Within 2 seconds, a raster scan of 12 horizontal lines can go through this array to produce a tone burst whenever the scan is crossing an illuminated photocell. It's proved that this system can only "perceive patterns such as two vertical lines, or an array of 6 dots." Thus, the lack of complex patterns makes it easy for blind people to identify the patterns in a short amount of time.

System Ⅱ, [The Flying Spot Scanner System]
In order to overcome the difficulty of presenting complex patterns, instrumentation system Ⅱ was designed and built. It's a flying spot scanner system which uses an oscilloscope to move a dot of light in a raster pattern. A cardboard figure pasted to the oscilloscope screen can cover the moving dot during parts of the scan, and this is detected by a photo multiplier tube placed in front of the oscilloscope. An analog computer was designed specifically for this project to produce the raster scan. This system, more flexible than previous system, is able to present any number of lines within any speed to program them easily.[2]

System Ⅲ, [The First TV Camera System]
This system can present an audio display of 30 lines within 8 seconds. It has constant scanning speed which doesn't vary with picture complexity. What's more, it uses one dimensional edge detection which means that there was no small up and down movement of the scan line as it moves from left to right as in system Ⅳ, The Second TV Camera System. Therefore, vertical or sloped lines can be detected, but those lines parallel to the scan line which are not crossed by the scan line won't be detected.

The TV camera was a "modified Robot Research Model 80". This camera is normally used for "amateur radio broadcasting of slow scan television pictures". During the test of this system, there are five subjects, including one blind subject who was a 10 years old boy, having been completely blind for 3 years. All of them were able to recognize objects as the were placed in front of the camera lens of this system. Specifically, the blind boy learned to identify 7 different objects with just one hour training with the audio code.

System Ⅳ, [The Second TV Camera System]
The second TV camera system was used to make tape recordings. These tapes helps people to determine how quickly patterns could be presented to subjects. Table Ⅰlists the results of these tests made with tapes produced by the flying spot scanner system. Among so many patterns in the right side of this table, those shapes in this table produced by flying spot scanner system are the square, the triangle, and the stars. Other patterns are coded by the second TV camera system. In order to gain fast speed with the TV camera, patterns are recorded at the same speed.

Reasons of Applying Optical-To-Auditory system
1.      The optical input can offer more comprehensive information as a sighted person see than other devices such as sonar which cannot see anything far, or through glass, or on paper.

2.      Hearing can convey different kind of information.

3.      Headphones seems to be the least harmful output.

Main Problems of Electronic Seeing Aids:
1.       Hearing is much slower than sight in terms of the amount of information or bit-rate, so there must be a data reduction on the process of transmission from sights to sounds. Then, how much of the data reduction can just effectively and quickly transit information to blind people is hard to determine.

2.       It's hard to find the best way to encode the data as a sound so that it matches the properties of aural system.

Data Reduction
There must be a considerable reduction in the quantity of information in order to convert an image into a sound.

Calculation of O’Hea (1987) estimated a reduction by a factor of 650 was necessary which is equal to a standard television picture being displayed every 13 seconds.

Forms of Sounds
Several previous attempts at producing optical-to-auditory devices:

1.      Fish (1976) – vertical position is mapped to tone frequency and horizontal position to binaural loudness difference.” (This kind of sound can be used to identify 18 test patterns with at most 4 hours training including those patterns not in the training.)

2.      Dallas (1980); O’Hea (1987); (Meijer (1992)) – vertical position is mapped to frequency, horizontal position mapped to time and brightness to loudness.

Future Work
Although real-time optophone helps lots of blind people, it's useless to the new users who can hardly distinguish those different sounds, let alone transform them into pictures in their mind. Therefore, the aid of optophone depends on a period of certain training to the blind.

Additionally, those sounds are difficult to follow, especially when a person want to read a long work by this machine, so optophone is not much used after 1920s. The emergence of later technology like scanner, optical character recognition machine we use today. In other words, even though optophone is not heard much after 1920s, it's a important step of many other optical scanning products. Looking through history, reading technology helps on people over the last century. Although the popularization and application of optophone failed, it established basis of other optical products, making people's lives more and more convenient. Meanwhile, optophone is just the one of the most advanced step helping disadvantaged group, blind people and there will be more and more people devote themselves into this development of helping the blind.