Intra ear canal hearing aid

Abstract

The present invention is in the field of an intra ear canal hearing aid, a pair of said hearing aids and use of said hearing aids. Such a hearing aid is designed to improve or support hearing. It typically relates to an electroacoustic device that is capable of transforming sound, thereby reducing noise and typically amplifying certain parts of the audio frequency spectrum. In addition such as hearing aid may improve directional perception of sound.

Claims

1. An intra ear canal hearing aid comprising: a housing, the housing comprising at least one input opening for receiving and at least one output opening for transmitting audio-signals, wherein the at least one opening for receiving and the at least one opening for transmitting are located at a distance of 1-10 mm, wherein the at least one input is upstream from the at least one output, a power source, and an audio processor, the audio-processor comprising a clock operating at a frequency of 1-100 MHz, at least one low-latency high resolution sigma-delta analogue-digital converter (ADC) for providing a 1-bit output stream, at least one ADC analogue input, at least one ADC digital output, at least one output being in electrical connection with a digital loop filter, at least one digital loop filter in digital connection with at least one ADC, having at least one digital output, the at least one digital loop filter preferably operating in a time domain, at least one pulse width modulating (PWM) controller for receiving digital output from the digital loop filter and providing PWM output, wherein the controller is programmable and adaptable, wherein the ADC latency in use is one clock cycle, at least one microphone capable of receiving audio-signals at a frequency of 5-25000 Hz, an active sound-canceller, for receiving input from the microphone and from the ADC, and for providing output to at least one output filter and at least one transducer, optionally an amplifier, at least one output filter, the output filter for receiving input from the sound canceller, wherein the output filter provides feed-back to the at least one ADC, and at least one transducer capable of providing audio-signals at a frequency of 5-25000 kHz.

2. The hearing aid according to claim 1, wherein the active sound canceller comprises at least one audio feedback controller and at least one audio feedforward controller, wherein at least one controller is adaptable, and wherein the feedback controller can control an input of the at least one sensor pair, for noise reduction, and can control multiple inputs of the sensors, and can obtain output from the transducer, and can control multiple outputs from the transducers, and wherein the feedforward controller controls the at least one transducer/sensor pair, for noise reduction, wherein the feedback controller provides at least one transfer function with reduced variability to the feedforward controller.

3. The hearing aid according to claim 1, comprising at least one spaced apart transducer/sensor pair, wherein a distance between a sensor and transducer d is preferably 0.1-0.5* length 1 of the sensor, and comprising at least one audio sensor, wherein sensors are located close to a side of the hearing aid being closest to the ear canal opening.

4. The hearing aid according to claim 1, further comprising at least one of a wireless transceiver, a motion sensor, a pressure sensor, and a positioner, and comprising in electrical contact with the ADC at least one of an amplifier, a decimation filter, an interface, and for data, a reference power source, a digital-analogue converter (DAC), a sampler, wherein the DAC comprises at least one digital audio input, and comprising at least one power stage.

5. The hearing aid according to claim 1, comprising at least two microphones, or an n*m array of microphones.

6. The hearing aid according to claim 1, wherein the transducer is selected from a MEMS, a moving coil, a permanent magnet transducer, a balanced armature transducer, and a piezo-element, and wherein the ADC comprises at least one further digital output.

7. The hearing aid according to claim 1, wherein the programmable pulse width modulating (PWM) controller comprises in series (i) at least two parallel loop filters for loop-gain and signal processing, each loop filter comprising multiple inputs and at least one output, wherein a loop filter is adapted to perform at least one of interpolation of the pulse code modulated (PCM) input signal, common mode control, differential mode control, audio processing, audio filtering, audio emphasizing, and LC compensation, characterized in that each single output being in electrical connection with (ii) at least one butterfly mixer, the butterfly mixer being capable of mixing at least two inputs and of providing at least two mixed outputs to (iii) at least two parallel pulse width modulators (PWM's), wherein a pulse width modulator comprises a carrier signal with an adaptable and programmable shape, phase and frequency, wherein the carrier signal is compared by the pulse width modulator with the input signal to create an output signal, wherein (iv) loop filters, butterfly mixer, and PWM's are individually and independently programmable and adaptable, wherein loop filter input is adapted to receive at least one of a local digital PWM processed output signal, and an ADC output, and comprising at least one setting data storage means for loading, adapting and storing programmable and adaptable settings.

8. The hearing aid according to claim 1, wherein in the PWM the loop filter comprises at least 3 filter stages, and wherein in the PWM the loop filter comprises at least 5 filter stages, each stage comprising at least one of (a) an input having at least one coefficient, (b) a feedback coefficient, (c) a feed forward coefficient, (d) an adder, (e) an output having at least one coefficient, and (f) a register comprising a processed signal, and wherein in the PWM the butterfly mixer comprises at least two stages, wherein in an initial stage outputs of two loop filters are mixed forming a mixed initial stage output, and wherein in a further stage outputs of two mixed previous stages are mixed forming a mixed further stage output.

9. The hearing aid according to claim 1, wherein the PWM controller comprises channels, and wherein a carrier signal of a first channel is programmed to be phase synchronous and/or frequency synchronous with a carrier signal of another channel, and/or wherein a carrier signal is disabled to leave a channel “free running” without enforcing fixed-frequency PWM, and wherein the PWM further comprises at least one analogue to digital converter (ADC) for converting an analogue signal into a digital signal, typically one ADC per loop filter.

10. The hearing aid according to claim 1, wherein the PWM's provide output to at least one crossbar, the crossbar comprising at least two outputs, a number of outputs typically being equal to the number of PWM signals, and wherein the PWM comprises at least one adaptable and programmable linear ramp generator with feed-in coefficients, for at least one of input volume control, controlling crossfading typically between feedback signals, and gradual application of DC offset, and wherein the housing is selected from at least one of a hollow housing, a flat housing comprising a fixing element, and wherein the ADC is configured to operate in at least one of differential use, single ended use, and true ground single ended use.

11. A pair of hearing aids, each hearing aid according to claim 1.

12. A kit of parts comprising a hearing aid according to claim 1 and an external low frequency aid.

13. A sensor/transducer pair for use in an intra ear canal hearing aid according to claim 1, wherein the sensor is surrounding the transducer, and a distance between the sensor and the transducer d is 0.1-0.5* length 1 of the sensor.

14. A set of sensor/transducer pairs according to claim 13, wherein the set comprises 2-10 pairs, wherein the pairs are adjacent to one and another.

Description

SUMMARY OF FIGURES

(1) FIG. 1-13a-c show details of the present hearing aid.

(2) FIG. 14 shows a flow diagram.

DETAILED DESCRIPTION OF FIGURES

(3) The figures are of an exemplary nature. Elements of the figures may be combined. In the figures: d distance between transducer and sensor l length of transducer/sensor 10 PCM input signal 11 filter stages input 12 scaled copy of input signal 15 PWM and ADC feedback signals 16 input further channel 17 output last filter stage 20 programmable loop filter 22 adder input 23 adder output 24 stage output signals 25 output signal loop filter 30 butterfly mixer 31 (identical) butterfly element 35 output signal butterfly mixer/PWM input 38 carrier signal 40 pulse width modulator (PWM) 42 pulse width modulator 45 PWM output signal 50 crossbar 55 controller output signals 60-62 feed-in coefficients 65-66 input selector/combiner 70 first filter stage signal summation 71 normal filter stage summation 75 filter stage 76 stage input signal 77 stage output signal 78 stage feedback signal 80-82 scaling coefficients 85 storage register 90 output coefficient 100 adder 100 (digital) controller 105 butterfly input 110 input scaling (e.g. 50%) 115 input selection 125 programmable adder 130 programmable adder output 135 programmable clipper 140 clip residue 145 inverter 150 multiplexer 155 adder 160 butterfly output signal 200 intra ear canal hearing aid 211 active sound canceller 213 audio sensor/microphone 214 transducer/speaker 215 additional audio sensor 218 audio feedback controller 219 audio feedforward controller 221 input opening 222 output opening 230 pinna 231 ear canal 232 ear drum 235 ear canal 236 virtual node 237 distance 250 housing 251 battery 252 cable connection 253 centering ring 254 support 255 transducer array 257 open air pathway 258 support structure 259 tool connection point 271 output 420 clock generation unit

(4) FIG. 1 shows typical parameter settings of the present hearing aid.

(5) FIG. 2a shows an example of how a 5th order digital loop-filter is able to achieve much higher loop-gain compared to a 2nd order analog filter.

(6) FIG. 2b shows measured THD+N results at the output of a 100W power amplifier that uses the present controller.

(7) FIG. 3 shows a digital core of the programmable PWM controller. The input 10 and feedback signals 15 enter the loop-filters 20 on the left, after the signals are filtered by the programmable loop-filters they 25 are fed to the butterfly mixer 30, which can make combinations of various loop filter outputs. The resulting signal 35 is fed to the actual pulse-width modulators 40. The crossbar 50 can permute the pulse-width modulated signals 45 before they are output 55 by the system.

(8) FIG. 4 shows blocks inside a single loop-filter. On the left, a programmable selection of input 10 and feedback signals 15 enter the loop-filter, where these are first processed with time-variable feed-in coefficients 60,61,62 and summed together 70. A number of cascaded loop-filter stages 75 further process the summed signal. The main output of the loop-filter 25 is formed by summing a scaled copy of the input signal 12 and a programmable selection of stage output signals 24. The output of the last filter stage 17 is an auxiliary output that can be used as input to a loop-filter in another channel 16.

(9) FIG. 5 shows a single loop-filter stage. It uses coefficients 80,81,82 to scale a the input that is shared for all stages 11, b the output of the previous stage 76, and c a feedback from this or a next stage 78. The scaled signals are summed 71 and fed to a storage register 85. The output of the register 77 is fed to the next stage and to an output coefficient 90.

(10) FIG. 6 shows a butterfly mixer that consists of a number of identical butterfly elements 31. The elements can be configured to mix their input signals such that a selection of loop-filter outputs 25 can be combined to create a selection of PWM inputs 35.

(11) FIG. 7 illustrates the similarity of the butterfly mixer to a radix-2 decimation-in-time FFT structure, which also provides the source of the term ‘butterfly element’.

(12) FIG. 8 shows a single butterfly element. It is a vertically symmetric structure which can scale and mix its two inputs 105 to create its two outputs 160. At the input side, either the normal input 105 or an input that is scaled by a half 110 can be selected 115. The mixing is done with the programmable adder 125 that can be configured to either pass an input, add the inputs, or subtract the inputs. The range of the mixed signals is limited with a programmable clipper 135. When the signal clips, the clip residue 140 can optionally be passed to the other side and added with the output there. This can be useful to compensate clipping errors.

(13) FIG. 9 shows an example of the present low latency ADC.

(14) FIG. 10 shows an exemplary embodiment of the present hearing aid audio processor.

(15) FIG. 11 shows an example of a hearing aid. Therein a pinna 230 is shown with an ear canal 231 and an ear drum 232. At least one ring 253, typically 2 to 5 rings, position the housing 250 of the device centrally within the ear canal 235. The housing is close to the eardrum typically 1-10 mm (237). The control algorithms and sensor emulate the expected signal at the virtual node 236 which is adjacent to the eardrum 232.

(16) FIG. 12 shows an example of a cross section of a hearing aid within a typical housing 250. Therein electronics and batteries 251, a cable connection 252, centering rings 253, axial support 254 and an insertion and extraction point 259 is provided, an audio sensor and transducer array 255 comprising of sensors 213 and transducers 214a, b, an open air pathway 257, a support structure 258, and an additional microphone 213 are shown.

(17) FIGS. 11 and 12 show generic concepts, such as a shaped cylinder 250 of approximately 7 mm diameter, some soft positioning support 253 in view of wearing comfort, and open air path 257, a deep insertion into the ear canal, a virtual measurement node 236 at or close to the eardrum, an axially located transducer and sensor (typically at least one single pair), electronics and battery 251 centrally located or in an outer shell of a cylinder, and a charge, and signal input coupling 252. Optional features are an insertion/extraction tool connection point 259, a wireless connectivity to a source, and a wireless connectivity to other wearables, such as for near field inter ear communication.

(18) FIG. 13a shows schematics of the present hearing aid. It is assumed a primary (1.sup.st) and secondary (2.sup.nd) audio source may be present. The hearing aid 200 is provided with sensors 213, transducers 214, an audio feedback controller 218, and an audio feedforward controller 219. An input opening 221, such as for a microphone 213, and an output opening 222, such as for a transducer 214, are typically present. The working principle is described above. In addition a transducer/sensor pair may be present. Preferably 2-10 pairs are present, such as 3-5 pairs. The pairs are preferably adjacent to one and another along a central axis of the ear canal and hearing aid.

(19) An additional audio sensor 215 may be present, either in the present hearing aid, or externally (in wireless connection), or both.

(20) FIG. 13b shows an enlargement of the transducer/sensor, in top view. The transducer and sensor may have any spatial form, and cross section, such as circular, ellipsoidal, multigonal, square, triangular, hexagonal, octagonal, etc. The transducer 214 is inside the sensor/microphone 213. Between the transducer and sensor a space is provided, which may be filled, or may be air. The sensor is at a distance d from the transducer. FIG. 13c shows a side view of the transducer/sensor pair, the transducer not being visible from an outside normally. The pair, and in particular the sensor, has a length l. Typically l is parallel to a longer side of the hearing aid and the ear canal. FIGS. 13b and c also show optional openings in the sensor.

(21) FIG. 14 shows a sound signal coming in and being processed in the hearing aid 200. Processed sound information is then send to output 271, such as for reducing noise. Feedback 218 is provided to the hearing aid. Also feedforward 219 is provided to the output. It is noted that sound cancelling may form part of the loop filter, or not.