| What is claimed is: 1. A device that enables deaf people to perceive sound comprising: a microphone configured to receive the analog audio signal from the user and from his or her teacher and output the said analog audio signal; an audio signal processing circuit configured to receive the said analog audio signal and covert it into a time domain amplified signal; at least two piezoelectric transducers configured to receive said time domain amplified signal and by means of which said piezoelectric transducers create minute vibrations of the user's skin, which stimulate the Pacinian corpuscles in the skin; the nerve impulses from the Pacinian corpuscles are transmitted to the brain and, as the impulses are in the form recognized by the brain as sound, they are perceived by the user as sound. 2. The device of claim 1 wherein said time domain amplified signal may be modulated onto a carrier wave. 3. The device of claim 1 wherein said piezoelectric transducers are made of zirconium titanate ceramic. 4. The device of claim 1 used in speech training for a sensorineural deaf child. 5. The device of claim 1 wherein the dielectric constant of said piezoelectric transducers is the same as human skin. 6. The device of claim 1 wherein the transducers are in the shape of a disk, a ball or a cup. |
Technical field of the Invention
The invention involves a device that enables deaf people to perceive sound. In particular, it enables deaf children to hear their own vocal utterances. It thus provides the auditory feedback essential to learning how to produce intelligible speech.
Background of the Invention
Children who are born deaf or have become deaf prior to learning how to speak do not ordinarily speak intelligibly because they can not hear the sounds they utter. Unable to hear the sound of their own voice, they don't learn how to form the sounds of their language.
At present, a sensorineural deaf child may be enabled to hear sound with a cochlear implant. The quality of the sound transmitted to a deaf person via a cochlear implant lacks the clarity enjoyed by people with normal hearing ability. Implantation requires surgery by a specialist in this field. The surgery is followed by an extended period of speech therapy to accustom the recipient to the sound characteristics of the implant. The cost of the implants is very high (US$30,000 - 50,000). The primary advantage of mis prosthetic approach is the mobility it offers to the recipient.
Attempts have been made to develop tactile hearing aids, using either electro-tactile or vibro-tactile contact with the user's skin. An example of electro-tactile stimulation is the Tickle-Talker. This device relies on electric stimulation of the fingers of the hand. The user must learn to associate the electric stimulations with different frequency ranges of sound in his/her surroundings. The same is true of current vibro-tactile devices. Neither type of tactile hearing aid converts the analog auditory input into a form that a sensorineural deaf person can perceive in the brain as sound.
Apart from the present invention, there is not a low cost alternative to the cochlear implant. Consequently, the vast majority of deaf children, particularly in developing countries, do not learn to communicate verbally with the hearing population. The result is a lifelong handicap that usually prevents the deaf child from developing to his or her full potential.
Summary of the Invention
The present invention is a device that enables deaf people to perceive sound which comprises: a microphone configured to receive the analog audio signal from the user and from his or her teacher and output the said analog audio signal; an audio signal processing circuit configured to receive the said analog audio signal and covert it into a time domain amplified signal; at least two piezoelectric transducers configured to receive said time domain amplified signal and by means of which said piezoelectric disks create minute vibrations of the user's skin, which stimulate the Pacinian corpuscles in the skin;
the nerve impulses from the Pacinian corpuscles are transmitted to the brain. As the impulses are in the form recognized by the brain as sound, they are perceived by the user as sound.
More specifically, said time domain amplified signal may be modulated onto a carrier wave. The dielectric constant of said piezoelectric transducers is the same as human skin. The transducers are in the shape of a disk, a ball or a cup. Said piezoelectric transducers are made of zirconium titanate ceramic.
The device enables deaf people to perceive sound and is used in speech training of a sensorineural deaf child.
The present invention enables deaf children to hear their own vocal utterances and thus provides the auditory feedback essential to learning how to produce intelligible speech. By means of the present invention deaf children can learn to communicate verbally with the hearing population using a low cost alternative to the cochlear implant.
Brief Description of the Drawings
Figure 1 illustrates the essential components of the present invention; Figure 2 is a circuit block diagram of the present invention;
Figure 3 is a detailed example of an example circuit used in an embodiment of the present invention.
Table 1 lists the values of components used in the example circuit. Description of Preferred Embodiments
Referring to Fig.l and Fig.2, a device that enables deaf people to perceive sound comprises a microphone 1, an audio signal processing circuit 2 and at least two piezoelectric transducers 3. The microphone 1 receives the analog audio information from the user and from his or her teacher. It outputs an analog signal to an audio signal processing circuitry 2. The audio signal processing circuitry 2 converts the incoming non-linear acoustic information into a time domain amplified signal. In operation, audio signal processing circuitry 2 processes the incoming complex non-linear waveform to remove the frequency component and leave only the time rate of change information contained in the analog signal. Thus, the frequency domain is suppressed and the time rate of change of the incoming signal is amplified. The amplified signal may be modulated onto a carrier wave. Methods for accomplishing this conversion are known in the art (see US Patent Nos. 3,647,970; 4,545,065; 4,819,199; 4,860,356). Figure 3 illustrates a representative example of a signal processing circuit.
This signal is then transmitted to piezoelectric transducers 3 which create minute vibrations of the user's skin stimulating the Pacinian corpuscles in the skin. Said transducers 3 are made of zirconium titanate ceramic and the dielectric constant of said transducers 3 is the same as human skin. Said transducers 3, usually two in number and usually disk-shaped, may be placed anywhere on the bare skin of the listener. The transducers 3 create minute vibrations of the skin which stimulate the Pacinian corpuscles in the skin. The transducers may be in the shape of a ball or a cup.
The Pacinian corpuscle is a nerve ending in the skin that transforms mechanical vibrations or pressures into nerve impulses. Research by Fernando Grandori and Antonio Pedotti of Milan, Italy (IEEE Transaction on Biomedical Engineering,, Vol BME-27, #10, Oct 1980) demonstrated that the Pacinian corpuscle can react to very high frequencies, and responds best to a square wave stimulus. Their work revealed that rate of change is more important than the amplitude of the pressure applied to the corpuscle. This skin receptor detects time significance first, and pressure significance secondly.
When the transducers 3 are in contact with the skin, the nerve impulses from the Pacinian corpuscles are transmitted to the brain. As the impulses are in the form recognized by the brain as sound, they are perceived by the user as sound.
In conclusion, the present invention receives analog auditory information and delivers it to the brain in the form required for perception of sound. It enables children with sensorineural deafness to hear their own vocalizations (and those of their teachers) and, thus, to learn to speak.
Table 1: The values of electronic components in Figure 3:
R1, R9 68 Ω
R2, R4, R5, R8 10 ΚΩ
R3, R12, R15 100 ΚΩ
R6 470 ΚΩ
R7 33 ΚΩ
R10 47 ΚΩ
Rll 100 Ω
R13 5.6 ΚΩ
R14 4.7 ΚΩ CI 100 uF
C2, C5 0.1 uF
C3 0.0047 uF
C4 0.001 uF
C6 0.01 uF
C7 33 pF
All transistors 2N3904 Choke coil (CC) 2 H
Input 8 Ω