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EP-4736471-A1 - ENTRAINMENT SYSTEM AND METHOD

EP4736471A1EP 4736471 A1EP4736471 A1EP 4736471A1EP-4736471-A1

Abstract

Methods and systems are disclosed for signal processing, in particular of an entrainment signal. A signal processing module is described which comprises a first signal input for receiving an input signal x in, a signal output for providing an output signal x out to an output device, and a second signal input for receiving a recorded signal y . The recorded signal y represents a recording of the output generated by the output device. The signal processing module further comprises signal processing circuitry configured to generate the output signal by adding the input signal and a difference α ( x ref - y) between a reference signal and the recorded signal: x out = x in + α ( x ref - y ). The reference signal can be the input signal, the output signal, or an external reference signal. The input signal can be an entrainment signal.

Inventors

  • OOMEN, Paulus

Assignees

  • Liquid Oxigen (Lox) B.V.

Dates

Publication Date
20260506
Application Date
20240625

Claims (15)

  1. 1. An analogue signal processing module for processing an entrainment signal, the signal processing module comprising: a first signal input for receiving an input signal; a signal output for providing an output signal to an output device; a second signal input, different from the first signal input, for receiving a recorded signal, the recorded signal representing a recording of output generated by the output device in response to receiving the output signal; and signal processing circuitry configured to generate the output signal by adding a difference between a reference signal and the recorded signal to the input signal, the reference signal being one of: the output signal, the input signal, or an external signal, the external signal being a recording of the output generated by the output device in response to receiving the output signal and being synchronised with the input signal.
  2. 2. The signal processing module as claimed in claim 1, wherein the output signal represents an audio signal, and wherein the output device comprises one or more loudspeakers, and wherein the recorded signal is recorded by a microphone.
  3. 3. The signal processing module as claimed in any one of the preceding claims, wherein the input signal, the output signal, the reference signal, and the recorded signal are analogue signals.
  4. 4. The signal processing module as claimed in any one of the preceding claims, wherein the circuitry comprises: an inverter for inverting the recorded signal, a first adder for creating a difference signal by adding the inverted recorded signal and the reference signal, and a second adder for adding the difference signal and the input signal; or a first inverter for inverting the reference signal, a first adder for creating a difference signal by adding the recorded signal and the inverted reference signal, a second inverter for inverting the difference signal, and a second adder for adding the inverted difference signal and the input signal.
  5. 5. A system comprising: one or more signal processing modules as claimed in any one of claims 1-4; one or more output devices, each output device being connected to the signal output of a respective signal processing module; and one or more groups of one or more recording devices, each group of one or more recording devices being connected to the second signal input of the respective signal processing module; wherein the group of one or more recording devices connected to the same signal processing module as a given output device is positioned in close proximity to the given output device.
  6. 6. The system as claimed in claim 5, the system being configured: as a headphones comprising a set of earcups, wherein each earcup comprises one output device and one recording device on the inside of the earcup; or as a set of earbuds wherein each earcup comprises one output device and one recording device configured to be inserted into a wearer’s ear canal.
  7. 7. The system as claimed in claim 5, wherein each output device and each group of one or more recording devices that are connected to the same signal processing module are configured as an environmental sound loudspeaker.
  8. 8. The system as claimed in claim 5, wherein the one or more output devices and the one or more groups of one or more recording devices are configured to be worn on or to be in contact with a predetermined set of body parts, preferably the predetermined set of body parts corresponding at least approximately to one or more of: crown, left shoulder, right shoulder, left hand, right hand, sternum, chest bone, sacrum, left knee, and right knee, left foot, and right foot.
  9. 9. The system as claimed in any one of claims 5-8, further comprising a signal generator for generating an input signal, preferably the input signal being an entrainment signal, preferably the entrainment signal having at least one main component with one or more of the following properties: i) a steady oscillation at one or multiple frequencies in the audible frequency range of 20 Hz - 20 kHz, and/or rhythmic pulsations in the sub-audible frequency range of less than 20 Hz; ii) either no significant changes or steady and repetitive periodic changes in the frequency spectrum and/or rhythmic components of the signal for the duration of the signal; and/or a rise and decay of the frequency spectrum and rhythmic components of the signal with relatively steady periodicities; iii) a variability in the periodic changes in the frequency spectrum and/or rhythmic components of the signal, the variability preferably being between 0-200 ms; iv) amplitude levels of the signal being less than 85 dB; v) reverberation of the signal in an environment which may be a recorded environment, a simulated virtual environment and/or the playback environment itself; and vi) a duration of at least one minute, preferably at least two minutes, more preferably at least five minutes.
  10. 10. A method for processing a signal, the method comprising: receiving or generating an input signal, preferably the input signal representing an entrainment signal; generating, in an environment, an output signal, based on the input signal; recording a recorded signal, the recorded signal representing the output signal having interacted with the environment; and modifying the output signal by adding a difference between a reference signal and the recorded signal to the input signal, the reference signal being one of: the output signal, the input signal, or an external signal, the external signal being a recording of the output generated by the output device in response to receiving the output signal and being synchronised with the input signal.
  11. 11. The method as claimed in claim 10, wherein the output signal is an acoustic signal generated by one or more loudspeakers, and wherein the recorded signal is recorded by a microphone.
  12. 12. The method as claimed in claim 10, wherein the input signal is an entrainment signal, preferably the entrainment signal having one or more of the following properties: i) a steady oscillation at one or multiple frequencies in the audible frequency range of 20 Hz - 20 kHz, and/or rhythmic pulsations in the sub-audible frequency range of less than 20 Hz; ii) either no significant changes or steady and repetitive periodic changes in the frequency spectrum and/or rhythmic components of the signal for the duration of the signal; and/or a rise and decay of the frequency spectrum and rhythmic components of the signal with relatively steady periodicities; iii) a variability in the periodic changes in the frequency spectrum and/or rhythmic components of the signal, the variability preferably being between 0-200 ms; iv) amplitude levels of the signal being less than 85 dB; v) reverberation of the signal in an environment which may be a recorded environment, a simulated virtual environment and/or the playback environment itself; and vi) a duration of at least one minute, preferably at least two minutes, more preferably at least five minutes.
  13. 13. The method as defined in claim 10 or 12, wherein a subject is present in the environment, preferably the subject being an organism, more preferably a human, and wherein interaction with the environment comprises interaction with the subject.
  14. 14. The method as claimed in any one of claims 10-13, wherein the method is a non-therapeutic method.
  15. 15. The method as claimed in any one of claims 10-14, further comprising obtaining the reference signal, the obtaining of the reference signal comprising: receiving the input signal; generating, in a reference environment, a reference output signal, while the reference environment does not comprise the subject; and recording the reference signal, the recorded signal representing the reference output signal having interacted with the reference environment without the subject.

Description

Entrainment system and method Technical field The disclosure relates to signal production, and in particular, though not exclusively, to methods and systems for generating an acoustic entrainment signal. The environment in which a sound (or other signal) is played, affects the acoustic properties (e.g., amplitude spectrum and phase spectrum) of the sound. The effects depend on, e.g., air temperature, humidity, distance to any boundaries (such as walls), used materials, and the presence of objects (including human beings) in the environment. For certain applications, it may be desirable that the sound that is sensed by an observer in the environment, deviates as little as possible from an intended sound. One such application is the therapeutic use of sound, in particular acoustic entrainment signals, as described for instance in WO 2022/039598 A1. However, as the aforementioned environmental effects may reduce the efficacy of the entrainment signals, a system is needed that optimises the generated signals, taking into account the environment. Hence, from the above, it follows that there is a need in the art for a system that compensates for the effect of the environment on the generated signal. It is an aim of embodiments in this disclosure to provide a system and method for processing or generating a signal such as an entrainment signal that avoids, or at least reduces the drawbacks of the prior art. In a first aspect, embodiments in this disclosure relate to a signal processing module. The signal processing module comprises a first signal input for receiving an input signal xin; a signal output for providing an output signal xout to an output device; a second signal input for receiving a recorded signal y, the recorded signal representing a recording of the output generated by the output device; and signal processing circuitry configured to generate the output signal by adding a difference a(xref - y) between a reference signal and the recorded signal to the input signal. The reference signal is one of: the output signal, the input signal, or an external signal. The external signal may be a recording of the output generated by the output device in response to receiving the output signal and being synchronised with the input signal. Thus, the signal processing module adjusts a signal based on a recording of the generated signal. For example, if the recorded signal comprises a lower amplitude for certain frequencies than the reference signal, the signal processing module may increase the amplitude of those frequencies such that the amplitude spectrum is more similar to, or even equals that of the reference signal. Typically, the signal comprises a plurality or range of frequencies with different amplitudes. The reference signal may represent a target signal. The input signal can be an entrainment signal. It has been found that the properties of an entrainment signal are affected by the subject (typically a person) being entrained. By compensating for this subject-dependent effect on the entrainment signal, the effect of the entrainment can be enhanced. In the context of sound applications, entrainment may be defined as: “The process whereby two interacting oscillating systems assume the same periodicity. Entrainment is a phenomenon that can be observed in physical and biological systems." This definition follows the definition in P. Oomen et al., ‘The Effects of Spatial Sound on Human Wellbeing’, The Works Institute (2021), available on-line at https://osf.io/udsjy. In other technological fields, the term entrainment is typically used to describe entrainment of signals. For example, in the context of (acoustic) noise cancelling, an antinoise signal is entrained by the adaptive filter in stages to become more similar to an acoustic noise signal (also referred to, in that context, as a reference signal), which as a result can be more effectively cancelled. In the present disclosure, the acoustic signal produced by the loudspeaker (and generally modified by the presence of the human subject) is entrained to the reference signal (the input signal or a signal derived thereof), so that the acoustic signal becomes more similar to the reference signal. Both are examples of entrainment in physical systems. However, the entrainment in the term “entrainment signal” refers not primarily to the entrainment of the signals themselves, but to entrainment of the physiology of a human subject as a result of exposure to the entrainment signal. Consequently, in the context of this disclosure, the term “entrainment” refers to entrainment between a physical and a biological system, unless otherwise specified (implicitly or explicitly). Thus, the term “entrainment signal” generally refers to a generated signal improving entrainment of the biological system, and not to, e.g., entrainment of the acoustic signal to the reference signal. It is noted that the circuits described herein differ from, e.g., active noise-cancelling circui