Week 3

This is article from another website about snoring detector

Introduction

The use of polysomnographic recording is a standard evaluation procedure for SRBD patients.

However, it is expensive and is not suitable for long term monitoring. Penzel developed a digital

recording device called MESAM IV, to monitor oxygen saturation, heart rate, snoring, and body

position in order to screen subjects for OSAS . They also indicated that this inexpensive implementation would allow the development of homecare systems for the analysis and long term monitoring of snoring.

The automatic scoring system of MESAM IV calculates oxygen desaturation index (ODI), heart rate variation index (HVI) and intermittent snoring index (ISI) to obtain an apnoea-hypopnoea index (AHI). The snoring sounds are recorded by means of a laryngeal microphone. If the proportion of sounds between 50Hz and 800Hz exceeds 50%, it is assumed that there is snoring. Intermittent snoring is defined as intervals between two detected snores longer than 5 seconds and shorter than 60 seconds. Evaluating snoring interval analysis on 68 patients with all degrees of obstructive sleep apnea, Penzel et al[6]. reported that correlation between snoring interval analysis and polysomnographically scored apneas was moderate (r=0.51) . Following this development, a number of validation studies on MESAM IV were presented [7-

11]. In those studies, the intermittent snoring index was found to have high sensitivity (92%-96%) but low specificity (16%-27%).

Diagram 1 : Structure of snore detector

Figure 1 : The prototype of snoring detector.

Below are the signal of snoring detector

Figure 2: Original signal taken by a microphone and A/D converter at 2kHz

Figure 3 : The reference voltage is set to zero, and all signals are set to have positive voltage

Figure 4: Extraction of the profile by finding the maximum voltage value in every 10 points (200Hz)

Figure 5: 10-points sum to amplify the peaks (20Hz)

Figure 6 : 10-point moving average to smooth the curve

Figure 7 : Sample data of snores and intermittent snores detection

 

Table 1 : Evaluation of the snoring detector in a lab environment

 

Table 2 : Evaluation of the snoring detector in a home environment

week 2

This is the website that related to my project.

- http://www.zen22142.zen.co.uk/Circuits/Alarm/snore_alm.htm

On this website, tell us about the snore alarm that use the vibration to wake the sleeper.The vibration is provided by a small motor housed in a small 35mm film case, which can be placed under the sleepers mattress or pillow. This circuit has a level control and peak display indicator, a variable trigger threshold and trigger indication.

                                                  Figure 1 :The circuit example  of the snore alarm.

                                                     

                                            Diagram 1 : Block diagram that used on this website.

From left to right we have the input transducer, which is a small ecm microphone insert. A low pass filter and amplifier built around op-amp IC1, to filter out some high frequency noises. The amplified sound is then converted to DC by a precision rectifier formed by op-amp IC2. The DC component is then filtered again and must be present for a few seconds to activate the delay circuit. The delay circuit uses op-amp IC3 as a level shifter and compares the charge on capacitor C8 to its reference input set by the threshold control, VR2. Once the threshold is reached, this triggers the timer and motor drive. The delay for the motor to run is fixed, but can be made variable by using a potentiometer for R15.

week 1

Activity : - Briefing by the committee of fyp(final year project).

                                  - Discuss with the adviser that is Sir Hisham Mohd Desa(HMD) about the title of the    

                                     project.

                                  - Search some information about the project that I have been choose.


Title of the Project: 

Home Monitoring of Snoring



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Why I choose this title?

This is because everybody in the world has the problem with breathing while sleeping. This is so poor to the person that snores while sleeping. Kids, teenagers or old people, all of them are snore while sleeping with various sound levels. We can die of Sleep Apnea, a sleeping disorder in which if we take long pauses while breathing in our sleep. However, most times our brain will eventually wake you up and make you take a breath. Snoring is a condition that is actually very bad because it reveals problems with our respiratory system. Let I introduce what is snoring.

What is snoring?

Snoring is a noise produced when an individual breathes (usually produced when breathing in) during sleep which in turn causes vibration of the soft palate and uvula (that thing that hangs down in the back of the throat). The word "apnea" means the abscence of breathing.

Snoring also is defined as a coarse sound made by vibrations of the soft palate and other tissue in the mouth, nose & throat (upper airway). It is caused by turbulence inside the airway during inspiration. The turbulence is caused by a partial blockage that may be located anywhere from the tip of the nose to the vocal chords. The restriction may occur only during sleep, or it may persist all the time and be worse when we are asleep. This is because our muscle tone is reduced during sleep and there may be insufficient muscle tone to prevent the airway tissue vibrating. During waking hours muscle tone keeps the airway in good shape; that's why we don't snore when awake.

 

Figure 1 : Show the structure of the nose and part of breathing involved.

Depending upon the degree of obstruction, the patient either exhibits partial collapse of the soft tissues of the upper airway and produces a noise, which we refer to as snoring, or with total obstruction of any portion of the collapsible airway, can experience a condition called apnea (total cessation of breathing for 10 seconds or longer), or hypopnea (50% or greater decreased in air exchange for 10 seconds or longer).

As a direct consequence of obstruction, the C02 in the blood increases and the oxygen level in the patient’s blood decreases proportionate to the severity of the airway obstruction. This disruptive pattern of breathing generates disruptive sleep patterns, the consequences of which being that those individuals exhibit increased fatigability, lethargy, decreased ability to concentrate, increased irritability, and morning headaches. Basically, those individuals are extremely tired due to their inability to get a good night’s sleep.

The immediate consequences of obstructive sleep apnea are readily recognizable. However, not so easily recognizable are the long-term cardiovascular effects secondary to obstructive sleep apnea that lead to an estimated 30,000 to 40,000 cardiovascular/cerebrovascular deaths per year. Untreated obstructive sleep apnea ultimately leads to an increased incidence of pulmonary and systemic high blood pressure and ventricular hypertrophy (thickening of the heart muscle). Moreover, significant decreases in the oxygen saturation of the blood during apneic episodes can lead to potentially lethal arrhythmia (alteration in the rhythm of the heart).

What causes the snoring?

While we are breathing, air flows in and out in a steady stream from our nose or mouth to our lungs. There are relatively few sounds when we are sitting and breathing quietly. When we exercise, the air moves more quickly and produces some sounds as we breathe. This happens because air is moving in and out of the nose and mouth more quickly and this results in more turbulence to the airflow and some vibration of the tissues in the nose and mouth.

When we are asleep, the area at the back of the throat sometimes narrows. The same amount of air passing through this smaller opening can cause the tissues surrounding the opening to vibrate, which in turn can cause the sounds of snoring. Different people who snore have different reasons for the narrowing. The narrowing can be in the nose, mouth, or throat.

Obstructive sleep apnea occurs when the muscles that support the soft tissues in your throat, such as your tongue and soft palate, temporarily relax. When these muscles relax, your airway is narrowed or closed, and breathing is momentarily cut off. When the muscles relax, your airway narrows or closes as you breathe in, and breathing momentarily stops. This may lower the level of oxygen in your blood. Your brain senses this inability to breathe and briefly rouses you from sleep so you can reopen your airway. This awakening is usually so brief that you don't remember it.

Sleeping position and snoring

When we are asleep, we are usually (though not always) lying down. Gravity acts to pull on all the tissues of the body, but the tissues of the pharynx are relatively soft and floppy. Therefore, when we lie on our backs, gravity pulls the palate, tonsils, and tongue backwards. This often narrows the airway enough to cause turbulence in airflow, tissue vibration, and snoring. Frequently, if the snorer is gently reminded (for example, with a gentle thrust of the elbow to the ribs or a tickle) to roll onto his or her side, the tissues are no longer pulled backwards and the snoring lessens.

References

http://www.stanford.edu/~dement/snoring.html

http://www.mayoclinic.com/health/sleep-apnea/DS00148/DSECTION=causes

http://www.snoringtreatment.com/

http://www.medicinenet.com/snoring/article.htm#tocb