Nasal breath monitor
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to a device for monitoring the flow of the nasal breath, and for making this information immediately available to the user with stereo headphones. 
     2. Description of the Prior Art 
     Breath monitors currently in use monitor the flow of breath through the mouth. The problem with these breath monitors is that they are unsuitable for use which is specifically directed towards relaxation and stress reduction, because the breathing techniques which have been found productive for relaxation and stress reduction require that the breath be directed through the nostrils. In addition, it is useful to examine the flow through each nostril seperately, because variations in their relative magnitudes have been shown to be both an indicator and a controller of the ultradian rhythm, a rhythm which is of fundamental importance in the regulation of physiological states in the body and their corresponding correlates in the mind. Finally, none of the breath monitors currently in use provide the user with an immediate output which is representative of the balance and smoothness of the breath. This is a problem because the user is then deprived of the benefit of feedback, which enhances the depth of relaxation and stress reduction. This invention eliminates these problems. 
     SUMMARY OF THE INVENTION 
     The invention relates to a device for making the user more aware of the quality of the breath. It comprises seperate sensors for each nostril to detect the flow of the breath, electronic circuitry to amplify and enhance the detected signal, and stereo headphones to bring this information to the ears of the user. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 and 2 are labelled representation showing a Nasal Breath Monitor, including the sensors, differential amplifiers, compressors, low-pass filters, power amplifiers, and headphones. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, an embodiment of the Nasal Breath Monitor is shown. The sensors (1,2,3) comprise miniature condensor electret microphones. They contain built in field effect transistor amplifiers. Their output is in the range from 1 to 100 millivolts. In addition to the two microphones 1, 2 for the nostrils, a third microphone 3 is employed as a reference sensor. This permits the use of a differential amplifier 4 in the first stage, reducing ambient noise and eliminating the audio feedback path between the microphones and the headphones 5. 
     The gain of the differential amplifier is adjusted so that low level mistracking is not a problem in the compressor 6. The compressor is an integrated circuit developed for noise reduction in the telephone system. Its use here is not for noise reduction, but rather to make the quiet sounds louder and the loud sounds quieter, so that the gain can be high enough to hear very gentle breathing without the user being deafened by the explosive turbulence of a sneeze. 
     A mono/stereo switch 7 is located between the compressor and the low-pass filter 8. The series resistors 9, which are part of the filter&#39;s cut-off circuitry, provide a convenient place to isolate this switch, which is useful for setting up the monitor. 
     The low-pass filter utilizes the remaining two amplifiers from the integrated circuit used for the differential amplifiers. It enhances tonal pleasantness, eliminating annoying high frequency whistling and also eliminating phase noise from the reference sensor, which otherwise becomes a problem when wavelengths are of the order of the seperation distance between the sensors. 
     Gain is adjusted with the potentiometer 10 between the filter and the power amplifier 11. A preamp output 12 is made available immediately before the potentiometer, to permit the user to adjust volume as desired without affecting the data quality. 
     BRIEF DESCRIPTION OF OPERATION 
     Referring to FIG. 2, the outputs of the left nostril sensor(2) and the reference sensor(3) are differentially amplified(4), so that ambient disturbances are cancelled. The dynamic range is greatly increased by signal compression(6), which is followed by low-pass filtering(8). Power amplification(11) is provided to drive the left headphone(5), so that the left ear hears an enhanced sound of the breath in the left nostril. The right channel operates in the same manner. 
     Referring to FIG. 1, in operation the monitor is first balanced by closing the mono/stereo switch(7). Both ears then hear the same sound, which is a mixture of the sound from both nostrils. Potentiometers(10) are then adjusted until the loudness is comfortable and the balance is such that the sound of the breath seems to be equally loud in both ears. The mono/stereo switch is then switched to stereo.