Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
  • H04R25/43—Electronic input selection or mixing based on input signal analysis, e.g. mixing or selection between microphone and telecoil or between microphones with different directivity characteristics
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
  • H04R25/55—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception using an external connection, either wireless or wired
  • H04R25/554—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception using an external connection, either wireless or wired using a wireless connection, e.g. between microphone and amplifier or using Tcoils

Definitions

• This patent relates to assisted-listening systems. More specifically, this patent relates to an assisted-listening device capable of determining and adapting to surrounding environmental conditions.
• Assisted-listening devices e.g., hearing aids and the like, should be capable of operating in, and being adaptable to, several environmental conditions.
• the assisted-listening device should to be capable of automatically selecting amongst various audio sources, e.g., telecoil, microphone, or auxiliary.
• One commercially available hearing aid utilizes a magnetic reed switch to provide magnetic field detection and automatic transducer mode selection.
• the magnetic reed switch Unfortunately, there are a number of limitations associated with utilizing the magnetic reed switch. Frequently, the reed switch lacks the sensitivity to operate with many types of telephones and often requires placing an external magnet onto the telephone handset earpiece.
• the reed switch requires use of a portion of the communicate device, such as a very limited space within the hearing aid. Furthermore, the reed switch may be susceptible to damage or performance changes if the hearing aid is dropped or subjected to extremely high magnetic fields — thus undermining the effective reliability of the assisted-listening system. Another shortcoming involves the added costs that are incurred to implement the reed switch into the assisted-listening system due to the additional components and manufacturing effort required.
• FIG. 1 is a schematic block diagram of an integrated circuit in accordance with one of the described embodiments;
• FIG. 2 is a schematic block diagram of an integrated circuit in accordance with another of the described embodiments; and, [0005]
• FIG. 3 is a schematic block diagram of an integrated circuit in accordance with still another of the described embodiments.
• an integrated circuit facilitates selection of an audio source mode in response to the detection of an external magnetic field.
• an integrated circuit for an assisted-listening device is operably disposed between a plurality of audio sources and a signal processing circuit.
• the integrated circuit may include a magnetic field sensor and a threshold comparator.
• a gate e.g., a multiplexer, may be operably coupled and responsive to the output from the magnetic field threshold comparator.
• the gate may include a plurality of inputs being capable of coupling to a variety of transducer outputs or auxiliary audio sources, e.g., magnetic (telecoil), acoustic (microphone).
• auxiliary audio sources e.g., magnetic (telecoil), acoustic (microphone).
• one of the audio sources or transducer outputs is selected to be output to the signal processing circuit.
• a manual override mode may be provided for allowing multiple audio source outputs and/or transducer outputs to be simultaneously presented to the signal processing circuit.
• an integrated circuit is operably disposed between a plurality of audio sources and a signal processing circuit.
• the integrated circuit may include a sensor for detecting an external magnetic field presence.
• a magnetic field threshold comparator may be operably connected to the sensor.
• a gate is operably responsive to the magnetic field threshold comparator.
• the gate includes a plurality of inputs and a gate output.
• the plurality of inputs are connected to the plurality of audio sources.
• the gate output comprises a plurality of mode signals and is connected to the signal processing circuit.
• the gate output is responsive to the magnetic field threshold comparator such that detection of the external magnetic field enables one of the plurality of audio source signals to be presented to the signal processing circuit.
• an integrated circuit may include a sensor for detecting an external magnetic field presence.
• a magnetic field threshold comparator may include a first input operably connected to a magnetic field threshold value and a second input operably connected to the sensor.
• the magnetic field threshold comparator further includes an output being adaptable for connecting to a signal processing circuit.
• the output comprises a first signal and a second signal and is determined in response to the comparison of the sensed external magnetic field and the magnetic field threshold value wherein the first signal is presented to the signal processing circuit when the magnetic field threshold value exceeds the sensed external magnetic field and the second signal is presented to the signal processing circuit when the sensed external magnetic field exceeds the magnetic field threshold value.
• FIG. 1 depicts an integrated circuit 10, shown in dotted lines, operably disposed between a plurality of audio sources 12 and a signal processing circuit 14.
• the integrated circuit 10 includes an magnetic field sensor 16 a magnetic field sensor amplifier 17 and a gate 18.
• the gate 18, preferably a multiplexer, is operably responsive to the output from the magnetic field sensor amplifier 17.
• the magnetic field sensor 16 may include a threshold comparator 26 wherein detection of a magnetic field is based upon whether the magnetic field strength detected is above or below a threshold level.
• the threshold level 19 can be fixed or adjustable.
• the magnetic field sensor amplifier 17 provides an output signal to the gate 18 to ensure desired operation.
• the gate 18 includes a plurality of inputs 20 for receiving the outputs of transducers or auxiliary audio sources, e.g., magnetic (telecoil), acoustic (microphone).
• a gate output 22 is coupled to the signal processing circuit 14 wherein one of the plurality of inputs 20 is selected to be output to the signal processing circuit in response to detection of an external magnetic field.
• FIG. 2 depicts an alternate embodiment of an integrated circuit 10'. It is to be understood that the present invention may be embodied in these and other configurations.
• the integrated circuit 10' includes a magnetic field sensor 16' that integrates therewith the magnetic field sensor amplifier 17'. An output of the magnetic field sensor 16' is coupled to a threshold comparator 26 with a threshold value input 19. The output of the threshold comparator 26 is then coupled to the gate 18. The threshold level again may be fixed or adjustable.
• FIG. 3. depicts an alternate embodiment of an integrated circuit 10", similar to that illustrated in FIG. 2 as integrated circuit 10'. As shown in FIG.
• signal shaping devices 29, e.g., biasing elements, amplifiers, filters, rectifiers, etc., and other circuit devices may also be incorporated in the design of the integrated circuit 10".
• Any of the embodiments of the integrated circuit 10, 10' and 10" may further include a manual override 24, which allows one or more than one of the plurality of inputs 20 to be manually selected and presented to the signal processing circuit 14.
• a manual override 24 allows one or more than one of the plurality of inputs 20 to be manually selected and presented to the signal processing circuit 14.
• Several techniques may be utilized to detect the presence of the external magnetic field — often referred to as a B-field — for the control of the gate 18, e.g., microphone-telecoil multiplexer (MT MUX) in presenting a signal to the signal processing circuit 14.
• MT MUX microphone-telecoil multiplexer
• Some B-field detection methods include, but are not limited to: • detection of a static B-field above or below a certain threshold level (the detection level can be hysteretic to guard against oscillatory behavior); • detection of the AC EMF generated by the telecoil when merely bringing the telephone handset into close proximity of the telecoil; • detection of the AC EMF generated by the telecoil in response to the audio signal transmitted by a telephone handset or a room loop; or, • any combination of the above.
• the static B-field detection method may be preferred because it is more robust in the presence of electromagnetic interference (EMI) — either environmental or man-made.
• EMI electromagnetic interference
• the other external B-field detection methods are susceptible to "false" B-field detection from EMI, which may result in an undesirable transducer mode selection change that would require user intervention to correct. Although all three detection methods may initially respond unfavorably to EMI, the first method is capable of automatically reverting back to proper transducer mode operation without user intervention once the EMI event has subsided.
• Another advantage of the static B-field detection method is that it can be configured with amplifiers which operate only at low frequencies, i.e., a very low bandwidth requirement, on the order of 10 Hz. This is very advantageous for the development of a detector and control circuit which operate with minimum power consumption.
• the silicon external B-field detectors may include: a lateral bipolar magnetotransistor (LBMT), a split-drain MAGFET, or a micro-electromechanical system (MEMS) type device.
• LBMT lateral bipolar magnetotransistor
• MEMS micro-electromechanical system
• a standard Hall effect sensor may also be utilized.
• Advantages of using the LBMT are: it is a very sensitive silicon device for the detection of B-fields; it is less noisy than the MAGFET device; and, it detects B- fields that are tangential to the silicon surface — which would be in the same direction as the maximum sensitivity of the telecoil, when using standard mounting methods to attach the IC to the body of the telecoil.
• the MAGFET and standard Hall effect sensor are sensitive to B-fields that are perpendicular to the silicon surface. This is a potential disadvantage for the LBMT that may require non-standard mounting techniques to attach the IC to the telecoil body to ensure that the telecoil has the same maximum B- field sensitivity orientation direction as the sensor device.
• power consumption of the B- field sensor should be 100 microwatts or less to extend the battery life of the hearing aid as much as possible.
• the MAGFET may also provide adequate sensitivity for use as a B-field sensor since LBMTs are routinely operated at milliwatt power levels to obtain high B-field detection sensitivity.
• the LBMT could be operated at a low duty cycle to save power, since the B-field detection circuitry does not require continuous operation.
• both the LBMT and the split-drain MAGFET can be utilized to generate a differential current output that is proportional to the B-field strength, either device could be readily integrated into the same silicon integrated circuit with a telecoil preamplifier commonly incorporated in assisted-listening devices.
• an override switch can be utilized to control MT MUX operation and provide a user the ability to manually select a mode of operation that allows both the telecoil and microphone outputs — or other audio sources — to be presented simultaneously to the signal processing circuit of an assisted-listening device. This feature is desirable in listening environments such as churches, auditoriums, and classrooms that are often wired with magnetic room loops to assist the hearing impaired wherein hearing aid users can simultaneously utilize the magnetic and the acoustic audio information supplied in these situations.
• each of the embodiments is capable of being readily incorporated with telecoil preamplifier electronics in "active telecoil" transducers at very low cost onto the same integrated circuit.
• Additional benefits may include: • providing the ability to automatically detect whether a telephone handset is in close proximity; • providing the ability to automatically select the appropriate audio source, i.e., microphone output, to be output to the signal processing circuitry of an assisted- listening device when the external magnetic field strength is less than a predetermined threshold level; • providing the ability to automatically select the appropriate audio source, i.e, telecoil output, to be output to the signal processing circuitry of an assisted-listening device when the external magnetic field strength is greater than a predetermined threshold level; • providing improved assisted-listening device reliability through an integrated circuit design that is more resilient and less susceptible to damage or performance shifts; • efficiently utilizing existing available space within the assisted-listening device; and, • reducing the complexity and cost of the assembly process for assisted- listening device manufacturers by reducing the number of device components.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Neurosurgery (AREA)
• Otolaryngology (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Measuring Magnetic Variables (AREA)
• Hall/Mr Elements (AREA)

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Citations (2)

• 2003
  • 2003-12-16 EP EP03819164A patent/EP1695592B1/de not_active Expired - Fee Related
  • 2003-12-16 DK DK03819164.9T patent/DK1695592T3/da active
  • 2003-12-16 DE DE60336766T patent/DE60336766D1/de not_active Expired - Lifetime
  • 2003-12-16 AU AU2003297233A patent/AU2003297233A1/en not_active Abandoned
  • 2003-12-16 WO PCT/US2003/040130 patent/WO2005062669A1/en active Application Filing
  • 2003-12-16 CN CNA2003801108494A patent/CN1887028A/zh active Pending

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