1. Intra ear canal hearing aid (200)

a housing (250), the housing comprising at least one input opening (221) for receiving and at least one output opening (222) 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,

a power source (251), and

an audio processor, the audio-processor comprising

a clock (420) operating at a frequency of 1-100 MHz, at least one (1-16) low-latency high resolution sigma-delta analogue-digital converter (ADC) for providing a 1-bit out^¬ put 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 (20) in digital con^¬ nection with at least one ADC, having at least one digital output (25) , the at least one digital loop filter prefera- bly operating in a time domain,

at least one pulse width modulating (PWM) controller (40) for receiving digital output from the digital loop filter and providing PWM output (45), wherein the controller is programmable and adaptable,

wherein in use an ADC latency of one clock cycle is obtainable,

at least one microphone (213) capable of receiving audio- signals at a frequency of 5-25000 Hz,

an active sound-canceller (211), 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 pro- vides feedback to the at least one ADC, and

at least one transducer (214) capable of providing audio- signals at a frequency of 5-25000 kHz.

2. Hearing aid according to claim 1, wherein the active sound canceller comprises at least one audio feedback controller (218) and at least one audio feedforward controller (219) , wherein at least one controller is adaptable.

3. Hearing aid according to any of claims 1-2, comprising at least one spaced apart transducer/sensor pair (213,214), wherein a distance between a sensor and transducer d is preferably 0.1- 0.5* length 1 of the sensor.

4. Hearing aid according to claim 2 or 3, wherein the feedback controller (218) can control an input of the at least one sensor pair (213), for noise reduction, and can control multiple inputs of the sensors (213), and can obtain output from the transducer (214), and can control multiple outputs from the transducers (214) .

5. Hearing aid according to any of claims 2-4, wherein the feedforward controller (219) controls the at least one trans^¬ ducer/sensor pair (213,214), for noise reduction, wherein the feedback controller provides at least one transfer function with reduced variability to the feedforward controller.

6. Hearing aid according to any of claims 1-5, comprising at least one audio sensor (215) , wherein sensors are located close to a side of the hearing aid being closest to the ear canal opening.

7. Hearing aid according to any of claims 1-6, further comprising at least one of a wireless transceiver, a motion sensor, a pressure sensor, and a positioner.

8. Hearing aid according to any of claims 1-7, comprising at least two microphones (213), or an n*m array of microphones.

9. Hearing aid according to any of claims 1-8, wherein the transducer (214) is selected from a MEMS, a moving coil, a permanent magnet transducer, a balanced armature transducer, and a piezo-element .

10. Hearing aid according to any of claims 1-9, 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.

11. Hearing aid according to any of claims 1-10, comprising at least one power stage.

12. Hearing aid according to any of claims 1-11, wherein the ADC comprises at least one further digital output.

13. Hearing aid according to any of claims 1-12, wherein the programmable pulse width modulating (PWM) controller (100) comprising in series

(i) at least two parallel loop filters (20) for loop-gain and signal processing, each loop filter comprising multiple inputs (10, 15) and at least one output (25), wherein a loop filter

(20) is adapted to perform at least one of interpolation of the pulse code modulated (PCM) input signal, common mode control, differential mode control, audio pro-cessing, audio filtering, audio emphasizing, and LC compensation,

characterized in that each single output (25) being in electri^¬ cal connection with

(ii) at least one butterfly mixer (30), the butterfly mixer being capable of mixing at least two inputs (25) and of provid^¬ ing at least two mixed outputs (35) to

(iii) at least two parallel pulse width modulators (PWM's)

(40), wherein a pulse width modulator (40) comprises a carrier signal (38) with an adaptable and programmable shape, phase and frequency, wherein the carrier signal is compared by the pulse width modulator (42) with the input signal (35) to create an output signal (45),

wherein (iv) loop filters, butterfly mixer, and PWM's are indi^¬ vidually and independently programmable and adaptable,

wherein loop filter input (15) is adapted to receive at least one of a local digital PWM processed output signal (45), and an ADC output, and

comprising at least one setting data storage means (440) for loading, adapting and storing programmable and adaptable set^¬ tings .

14. Hearing aid according to any of claims 1-13, wherein in the PWM the loop filter (20) comprises at least 3 filter stages

(75) .

15. Hearing aid according to any of claims 1-14, wherein in the PWM the loop filter (20) comprises at least 5 filter stages (75) ,

each stage comprising at least one of (a) an input (11) having at least one coefficient (80), (b) a feedback coefficient (82), (c) a feed forward coefficient (81), (d) an adder (71), (e) an output (24) having at least one coefficient, and (f) a register (85) comprising a processed signal.

16. Hearing aid according to any of claims 1-15, wherein in the PWM the butterfly mixer (30) comprises at least two stages, wherein in an initial stage outputs (25) 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 (35) .

17. Hearing aid according to any of claims 1-16, wherein the PWM controller comprises channels, and wherein a carrier signal (38) of a first channel is programmed to be phase synchronous and/or frequency synchronous with a carrier signal (38) of another channel, and/or wherein a carrier signal (38) is disabled (41) to leave a channel "free running" without enforcing fixed-fre^¬ quency PWM.

18. Hearing aid according to any of claims 1-17, wherein the PWM further comprises at least one analogue to digital converter (ADC) (300) for converting an analogue signal into a digital signal, typically one ADC per loop filter.

19. Hearing aid according to any of claims 1-18, wherein the PWM' s (40) provide output (45) to at least one crossbar (50), the crossbar comprising at least two outputs (55), a number of outputs typically being equal to the number of PWM signals (55) .

20. Hearing aid according to any of claims 1-19, wherein the PWM comprises at least one adaptable and programmable linear ramp generator with feed-in coefficients (60-62), for at least one of input volume control (60), controlling crossfading typically be- tween feedback signals (61,62), and gradual application of DC offset .

21. Hearing aid according to any of claims 1-20, wherein the housing is selected from at least one of a hollow housing, a flat housing comprising a fixing element.

22. Hearing aid according to any of claimsl-21, wherein the ADC is configured to operate in at least one of differential use, single ended use, and true ground single ended use.

23. Pair of hearing aids, each hearing aid according to any of claims 1-22.

24. Use of a hearing aid according to any of claims 1-17 or a pair according to claim 18, for one or more of noise cancellation, as a hearing aid, for noise reduction, for medical application, during imaging, for brain stimulation, for damping of sound, for communication especially under noisy conditions, and for electroencephalography (EEG) measurements.

25. Kit of parts comprising a hearing aid according to any of claims 1-24 and an external low frequency aid.

26. Sensor/transducer pair for use in an intra ear canal hearing aid, 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.

27. Set of sensor/transducer pairs according to claim 26, wherein the set comprises 2-10 pairs, wherein the pairs are ad^¬ jacent to one and another.