Editorial board editor-in-chief

Fig. 5.
left: STFT of a normal signal; right: STFT of an abnorm signal
Table 2.
Acoustic parameters of snoring sound
Occasional snorer
Habitual snorer
Subject
Minimum Energy [dB]
Maximum Energy [dB]
Mean Energy [dB]
Standard Deviation [dB]
Median Energy [dB]
number of snorers/minute
number of breathing/minute
M0 [a.u.]
M1[a.u.]
M2 [a.u.]
F1 [a.u.]
F2 [a.u.]
F3 [a.u.]
F4 [a.u.]
44.92
61.02
48.64
1.45
48.57
7.00
15.00
426.00
44.00
2939.35
127.00
2499.00
2748.00
3123.00
47.20
58.67
57.47
1.95
57.83
10.00
10.00
2620.00
72.00
6267.81
125.00
1249.00
1874.00
2998.00
45.56
47.88
46.66
0.29
46.68
0.00
15.00
427.00
44.00
3149.44
127.00
1400.00
2374.00
2748.00
Acoustic characteristics of snoring sounds, which are ap-
proximately periodic waves with noise, can be analyzed also by 
using the multidimensional voice program MDvP.Multiple pro
-
tocols of MDvP can show differences between markers used 
in an automatic analysis e.g. peak frequency, soft phonation 
index (SPI), noise to harmonics ratio (NHR), and fundamental 
frequency variation (vF0). Measurements (Meas.1-4) results 
compared with norms are shown on polar diagrams that are 
very easy to interpret. 
Table 3. 
Parameters vF0, SPI, NHR for habitual snorer (male)
Parameters
Norm
Standard 
Deviation
Meas.1
Meas.2
Meas.3
Meas.4
vF0 [%]
SPI
NHR
0.94
6.77
0.12
0.43
3.78
0.01
68.73
7.49
3.55
45.26
6.37
1.54
43.26
0.63
2.79
43.32
5.09
3.79

---

41
T
elema
tics
Snoring as a sign of abnormality
future treatment and inluence of various environmental factors 
on a good night sleep. Green color in the polar diagram shows 
the standard and red color represents the pathological changes 
in snoring event for a single patient(ig. 6). Parameters which 
describe snoring sound, presented in this easy and transparent 
way, can be clearly interpreted - the most important parameters 
of snoring sound like vF0 and NHR are above normal value.
Utilization of acoustic methods yields research results in 
a straightforward, graphical way. Proposed methods can support 
snoring individuals cope with this disorder. Based on this method, 
investigators can judge what kind of disorders they are dealing 
with. Acoustic diagnosis of sleep disorders, especially of the Ob
-
structive Sleep Apnea Syndrome, is expected to provide a solution 
for snoring rehabilitation and making decisions concerning the 
Conclusion 
Acoustic analysis techniques used in this work gave information 
about loudness and intensity of the snoring sound. Analysis of 
results led to the conclusion that the curved septum is a possible 
reason of obstruction of the upper airways.
Close examination of snoring sound signal during various 
stages of sleep demonstrated that light snorers snored evenly 
throughout all of them. The most interesting fact was that ha
-
bitual snorers tend to snore more with maximum snoring inten-
sity in the rapid eye movement (REM) sleep phase than in any 
other stage of sleep (every 90 minutes). Further conclusions 
can be made by comparing simultaneously gathered acoustic 
and electrocardiographic signals. The first study showed that 
during two thirty-minutes intervals, starting at 130 and 300 
minutes after recording initiated, a significant decrease in 
Heart Rate Variability (HRV) can be seen, especially short term 
SDANN (Standard Deviation of the Averages of NN (Normal 
Sinus to Normal Sinus) intervals in all 5-minute segments of 
a 24-hour recording), which is in accordance with RMSSD 
(Root Mean Square Successive Difference - in heart period 
series is a time domain measure of heart period variability). 
During said intervals an increase of snoring sound intensity 
can also be seen. Snoring as a marker of abnormality can be 
only used in context of patient’s medical history. The history 
and related diagnostic tests help to determine whether the 
patient has abnormalities or is just a healthy snorer without 
other disorders (habitual or occasional snorer). For snor
-
ing patients common abnormalities include sleep disorders, 
breathing disturbances or apneas during sleep and other 
daytime disturbances. 
Fig. 6.
Polar diagram of MDvP (left: second snoring event, right: third snoring event) for a single patient
By combining results from the tests summarized in this paper 
with polysomnography tests and patient history iles, physi
-
cians will be able to better diagnose the patient and indicate 
the functional nocturnal and daily disturbances. It is also crucial 
that as many characteristics of snoring events as possible are 
recorded, for instance were they recent or longstanding, continu-
ous or intermittent, what was the sleeping arrangement, were 
there any movements of the body or legs during the sleep. In 
addition, factors like morning headaches, daytime sleepiness, 
alcohol consumption and smoking, as well as patient’s lifestyle 
in general, should be monitored. 
Acknowledgment
This Scientiic work is supported by the Polish State Committee for 
Scientiic Research resources in years 2009-2012 as a research 
project No. N N518 426736.
References
1. Zieliński T. (2005): Digital Signal Processing (in Polish). 
WKiL, Warszawa.
2. Guilleminault C., Stoohs R., Duncan S. (1991): Snoring (I). 
Daytime sleepiness inregular heavy snorers. Chest 99(1), 
pp. 40–48.
3. Urschitz M.S., Guenther A., Eitner S. et al. (1991): Risk 
factors and natural history of habitual snoring. Chest 126, 
pp. 790–800.

---

T
elema
tics
42
Snoring as a sign of abnormality
4. Basztura C. (1988): Źródła, sygnały i obrazy akustyczne. 
WKił, Warszawa.
5. Perez-Padilla R., Remmers J.E. (1985): Dynamics of pres
-
sure, airlow, and noise production during simulated snor
-
ing. Am Rev Respir Dis 131, p. 106.
6. Kłaczyński M. (2007): vibroacoustic phenomena in the hu
-
man voice channel (in Polish). PhD thesis. AGH, Kraków.
7. Dalmasso F., Prota R. (1996): Snoring: analysis, measure
-
ment, clinical implications and applications. European Re
-
spiratory Journal 9, pp. 146-159.
8. Hunsaker D., Riffenburgh R. (2006): Snoring signiicance in 
patients undergoing home sleep studies. Otolaryngology-
-Head and Neck Surgery 134, pp. 756-760.
9. Pevernagie D., Aarts R., de Meyer M. (2010): The acous
-
tics of snoring. Sleep Medicine Reviews 14, pp. 131-144.

---

T
elema
tics
BIO-ALGORITHMS AND MED-SYSTEMS
JOURNAL EDITED BY JAGIELLONIAN UNIVERSITY – MEDICAL COLLEGE
Vol. 7, No. 13, 2011, pp. 43-48