Study Of Pink Noise Hypnosis Instrument Based On DSP

As increasing pressure and change of habit brought by the modernization,the number of insomnia patients is increasing every year. Traditional insomniatreatments such as medication therapy, psychological therapy and Chinesemedicine therapy exists some drawbacks. And physical therapy emergingrecently is comparatively safe and effective, while study of related product is stillin elementary stage. According to the mechanism of sleep, the positive effect ofpink noise on human sleep structure and efficiency was confirmed throughanalyzing the similar characteristics of EEG waveform during sleep and pinknoise. And the study of pink noise hypnosis instrument was started.According to the spectrum decomposition theorem of noise model structure,steady color noise can be obtained after steady white noise goes through a lineartime invariant system. However, white noise which is produced by computersoftware directly was found to be pseudo random sequence. It mainly has twoshortcomings: nonstationary and colored. And its functional properties are muchdifferent compared with ideal white noise. In line with this problem, an effectivemethod employing piecewise smooth and compensation was proposed in thispaper. And a five-order AR model of pink noise was established by AR modelmethod as well as a five-order IIR filter. With the smooth white noise as drivesignal, the pink noise needed for the sleep instrument can be obtained afterfiltering.In order to verify the characteristic of pink noise generated by the ARmodel, simulation experiments were carried out on LabVIEW platform.Programs including the realizing of whitening method and the AR model and theplaying of the pink noise were completed. This new whitening method and theAR model was verified by comparing power spectrum of pseudo randomsequence and white noise obtained after whitening processing as well as the pinknoise. The results show that: the white noise after whitening was improvedgreatly both on uniformity and stability. This new whitening method is effective. The noise generated by the AR model accords with the performance requirementof pink noise. The AR model is practicable. Pink noise drived by whitened whitenoise and filtered by the AR model has good performance and fits with idealpink noise in high degree. The sound of it is soft.After the algorithms proposed were proved effective, the software system ofthe hypnosis instrument was designed with modular method based onICETEK–F2812-A evaluation board of Realtime company. Algorithms mainlyincluding creating and whitening pseudo Gaussian noise and designing IIR filterwere completed on CCS development platform using C language. And Powerspectrum of pink noise was analyzed in order to further verify its performance.