Earphones for measuring and entraining respiration

1. A system comprising:

an earphone comprising:

a loudspeaker;

a microphone;

a housing supporting the loudspeaker and the microphone;

an ear tip surrounding the housing, the ear tip being configured to acoustically couple both the loudspeaker and the microphone to an ear canal of a user, and to acoustically close the entrance to the user's ear canal;

and

a processor configured to:

provide output audio signals to the loudspeaker;

receive input audio signals from the microphone;

extract a rate of respiration from the input audio signals;

adjust the output audio signals based on the extracted rate of respiration; and

provide the adjusted output audio signals to the loudspeaker,

wherein:

providing the output audio signals to the loudspeaker comprises providing signals which represent sounds across a first frequency band, the audio signals including a notch in which the sounds lack energy within a second frequency band narrower than the first frequency band; and

the processor is configured to extract the rate of respiration by

applying a band-pass filter to the input audio signals to limit the input audio signals to a third frequency band contained within the second frequency band; and

demodulating the filtered input audio signals to compute the rate of respiration corresponding to energy in the input audio signals in the third frequency band.

2. The system of claim 1 , wherein adjusting the output audio signals comprises adjusting a rhythm of the output audio signals to be about one cycle per minute less than the extracted rate of respiration.

3. The system of claim 1 , wherein adjusting the output audio signals comprises transitioning the output audio signals from respiration entrainment sounds to masking sounds.

4. The system of claim 1 , wherein adjusting the output audio signals comprises transitioning the output audio signals from masking sounds to awakening sounds.

5. The system of claim 1 , wherein

the earphone further includes a memory storing sound files; and

providing the output audio signals comprises retrieving a first sound file from the memory.

6. The system of claim 5 , wherein adjusting the output audio signals comprises retrieving a second sound file from the memory and using the second sound file to generate the output audio signals.

7. The system of claim 1 , wherein the processor is integrated within the earphone.

8. The system of claim 1 , wherein the processor is integrated within a portable computing device.

9. The system of claim 1 , wherein the third frequency band is coextensive with the second frequency band.

10. The system of claim 1 , wherein the second frequency band extends between 250 Hz and 350 Hz.

11. The system of claim 1 , wherein

the earphone further includes a memory storing sound files;

providing the output audio signals comprises retrieving a first sound file from the memory;

the first sound file represents audio signals corresponding to sounds having energy in the second frequency band, and

providing the output audio signals further comprises, in the processor, applying a notch filter to audio signals generated from the first sound file, to remove energy from the signals within the second frequency band.

12. The system of claim 11 , wherein:

the first sound file represents audio signals corresponding to sounds lacking energy in the second frequency band.

13. A system comprising:

an earphone comprising:

a loudspeaker;

a microphone;

a housing supporting the loudspeaker and the microphone;

an ear tip surrounding the housing, the ear tip being configured to acoustically couple both the loudspeaker and the microphone to an ear canal of a user, and to acoustically close the entrance to the user's ear canal;

a second earphone comprising:

a second loudspeaker;

a second microphone;

a second housing supporting the second loudspeaker and the second microphone; and

a second ear tip surrounding the second housing, the second ear tip being configured to acoustically couple both the second loudspeaker and the second microphone to a second ear canal of the user, and to acoustically close the entrance to the user's second ear canal;

and

a processor configured to:

provide output audio signals to the loudspeaker;

receive input audio signals from the microphone;

receive second input audio signals from the second microphone;

extract a rate of respiration from the input audio signals and the second input audio signals by:

combining the input audio signals from the first microphone with the second input audio signals from the second microphone, and detecting peaks having a frequency of around 1 Hz within the result of the combination;

based on the detected peaks, computing an instantaneous heart rate;

measuring a frequency of an oscillation within the instantaneous heart rate; and

based on the frequency of the oscillation, compute the rate of respiration;

adjust the output audio signals based on the extracted rate of respiration; and

provide the adjusted output audio signals to the loudspeaker.

14. The system of claim 13 , wherein the processor is configured to measure the frequency of the oscillation within the instantaneous heart rate by computing a fast Fourier transform (FFT) of the instantaneous heart rate.

15. The system of claim 13 , wherein the processor is configured to measure the frequency of the oscillation within the instantaneous heart rate by

computing a gradient of the instantaneous heart rate; and

computing a fast Fourier transform (FFT) of the gradient of the instantaneous heart rate.

16. The system of claim 13 , wherein the processor is configured to measure the frequency of the oscillation within the instantaneous heart rate by detecting peaks of the instantaneous heart rate.

17. The system of claim 13 , wherein the processor is configured to measure the frequency of the oscillation within the instantaneous heart rate by fitting a sine function to the instantaneous heart rate, the frequency of the sine curve being the frequency of the oscillation.

18. The system of claim 13 , wherein combining the input audio signals comprises multiplying the amplitudes of the first input audio signals by the amplitudes of the second input audio signals, at each time that the two signals are sampled.