Electrical audio signal processing systems and devices – Hearing aids – electrical – Remote control – wireless – or alarm
Reexamination Certificate
1995-02-03
2001-10-23
Mei, Xu (Department: 2644)
Electrical audio signal processing systems and devices
Hearing aids, electrical
Remote control, wireless, or alarm
C381S331000
Reexamination Certificate
active
06307945
ABSTRACT:
This invention relates to hearing aid systems, and in particular to improving the clarity of sound delivered to the ear by such hearing aid systems.
An impaired ear is unable to select an individual sound source when confronted with several other sources simultaneously and most hearing aid devices are designed to enhance the chosen source.
An Ear-trumpet was a most useful device in that it addressed the requirement to direct the sound source (at the bell) directly into the ear. Early electronic hearing aids introducedamplification. The bell of the Ear-trumpet was replaced by a microphone and the ear-piece of the trumpet was placed by a loudspeaker. This provided hands-free operation but the microphone was in a fixed position, relaying all surrounding sounds to the ear via the amplifier. Continuous noise and ugly appearance limited the success of these devices.
Hearing aid design has been side-tracked by the less important aspects of hearing aids, in particular their size, appearance and placement. These factors may well seem important to newly diagnosed sufferers of hearing loss, but are of considerably less importance to long term sufferers who would prefer improved performance. Behind-the-ear and in-ear hearing aids help to disguise the user's disability but this has meant that the microphone was also concealed, resulting in poor directionality, which in turn resulted in a poor signal to noise ratio.
Research to improve hearing aids concentrated on reducing hearing aid size, often by including complex electronics within the device. This approach has often negated the effectiveness of the aid in terms of clarity of sound and ease of use. For example, the effect of the user's head causes a microphone (in a behind-the-ear and in-ear hearing aid) to be less directional—often resulting in the picking up of sounds from outside the user's desired range. Furthermore, in difficult listening conditions, such as a crowded room, the hard of hearing will often turn the head so that the better ear faces the speaker in order to improve the signal to noise ratio, but in doing so the aid is then pointing in the wrong direction. This situation highlights one of the major problems with existing hearing aids—the aid can, at best, only enhance sounds coming from the direction in which the user is facing.
A further major problem is that of head shadowing, a condition which occurs when the head is between the hearing aid and the sound source, thereby rendering many sound sources inaudible.
An additional problem with existing hearing aids is that they have no facility for discreetly and easily adjusting the functionality of the hearing aid so as to select the best listening conditions at a given moment. Although remote control aids are available, they do not adequately address or overcome the fundamental problems mentioned above. With conventional behind-the-ear and in-ear hearing aids the volume controls are minute and relatively inaccessible when the hearing aid is in use. Aged, disabled and arthritic people can not easily adjust the hearing aid controls and many users simply can not feel the click of a volume adjustment wheel when switching an in-ear hearing aid off.
Directional behind-the-ear or in-ear hearing aids make side-by-side conversations difficult, as the aid is set to capture sounds from the direction in which the user is facing. In these circumstances it is often better not to have the aid switched on, but with the difficulties of regulating and/or adjusting the miniaturized controls this is often impractical.
Finally, because designers have placed the microphone so close to the loudspeaker (in the ear-piece), the volume threshold is considerably lower. This means that to avoid whistling feed-back the user must either avoid loud sound sources or set the volume control at a low level.
An aim of the present invention is to overcome all of the aforementioned disadvantages and to devise a system putting the performance of the hearing aid system ahead of appearance and size.
According to a first aspect of the invention there is provided a hearing aid system comprising: a unit having a microphone and a transmitter; a receiver unit for receiving a signal from the transmitter unit; the receiver unit being contained in a housing with an amplifier; an induction loop connected to the amplifier; and an ear piece capable of receiving a signal from the induction loop and transmitting an audio signal.
According to a second aspect of the invention there is provided a hearing aid system comprising: a portable device having a microphone and a transmitter; a receiver unit for receiving a signal from the transmitter unit; the receiver unit being contained in a housing with an amplifier; an ear piece for connection to the amplifier and receiving a signal therefrom, and for transmitting an audio signal.
Preferably the housing containing the receiver unit and the amplifier is in the form of a pendant which may be suspended around a user's neck. However, it will be appreciated that the housing may be carried in a user's pocket or attached to the clothing.
Because the microphone is built into a small hand-held unit, which is preferably portable, along with a transmitter, which is preferably transmitting at radio frequency, the unit is free to be moved independently of the head thus avoiding the aforementioned problems of head shadowing and partial directivity and frequency response.
The microphone can always have a clear view of the sound source. In many situations it can be placed by the sound source, permitting the user to move freely around and independently of the microphone, thus maintaining the best possible access to the sound source. With the microphone being placed well away from a loudspeaker or ear-piece, feedback will not occur until the amplification levels exceed the ear's natural threshold. This means that the user has access to far greater amplification than before. In addition the signal is of higher quality than previously obtainable on account of its superior directivity. Signal quality is further improved as the hearing aid operates almost silently in the ‘T’ mode. Ambience is also reduced as the microphone is able to effectively reduce its distance from the sound source.
Additionally, the invention also provides for functional controls of the system to be located on the remote unit, with possibly some of the controls located on the pendant. These controls may be designed so that they are large and adapted for easy use by infirm persons. This makes the device extremely user-friendly enabling simple and accessible control of the whole arrangement. It is much easier to adjust the controls on the hand-held unit as this is a relatively large device and the controls are visible to the user. This is a considerable improvement upon the controls of existing behind-the-ear or in-ear hearing aids. The ability to easily control the volume level of the hearing aid results in improved hearing. The controls are designed in particular to be accessible to the elderly which comprise the majority of users, and also the arthritic and infirm user.
According to a third aspect of the present invention there is provided a directional microphone for receiving an audio signal for subsequent amplification.
The signal may be transmitted to a remote amplifier.
A particular feature of the invention is the capability of the microphone to be operated either directionally or as an omnidirectional microphone, thus providing greater flexibility in sound directionality requirements of the user.
The receiver unit may be fitted with a local microphone, thus giving the user more flexibility in his choice of access to sound sources. The local microphone can be used instead of temporarily returning the hearing aid to its own built-in microphone. Furthermore, the receiver unit amplifier can be provided with frequency equalizers to adjust the sound received to remove unnecessary frequencies and to boost others.
Means may be provided on a housing containing the microphone and transmitter, for selecti
Mei Xu
Salter & Michaelson
Sense-Sonic Limited
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