Snoring: Is It in the Ear of the Beholder?

Abstract

Summary: Complaint of snoring, which is usually voiced by a patient's bedpartner, frequently leads to investigations in the sleep laboratory that are designed to assess snoring objectively and determine whether it is a symptom of sleep apnea. How well this subjective complaint of the listener is confirmed by the objective measurement of snoring is not known. Consequently, we designed a study i) to test the validity of self-perception of snoring and ii) to compare subjective perception of snoring by the sleep technologist with objective measurement of its frequency and loudness. We studied 613 unselected patients referred to our sleep clinic because of snoring and suspicion of sleep apnea. They all had nocturnal polysomnography that included measurements of snoring, expressed as the number of snores per hour of sleep [snoring index (SI)] and mean (dBmean) and maximum (dBmax) nocturnal sound intensity. Following the sleep study, the technologist (and patient) independently rated a patient's snoring as none, mild, moderate or severe. Kruskall-Wallis test, Spearman rank correlations and Cohen's kappa statistics were used to compare the groups, examine the correlations between subjective and objective measurements, and check the agreement between them. We found that i) most patients who snore (471 of 613) were unaware of this behavior; ii) snoring index increased progressively from the “none” group (median SI = 26) to the “severe” group (median SI = 755), with a significant but moderate correlation between the technologist's impression and SI (r = 0.68, p < 0.0005) and poor correlation between the technologist's impression and dBmean (r = 0.34, p < 0.0005); and iii) most of those patients who claim to be able to judge the severity of their snoring have a different perception of it than the listener, with poor agreement between patient's and technologist's subjective impression (Cohen's kappa = 0.22, 95% confidence limits: 0.14−0.33). We conclude that to a large extent snoring is “in the ear of the beholder”, showing only moderate correlation with objective measurement.

Breathing and Snoring Sound Characteristics during Sleep in Adults

“…10 In the absence of a conclusive definition, the following description of snoring was defined for this study: snoring is relatively loud breathing sounds ( > 50 dB) during sleep. 14,15 Using the detected breathing events, four acoustic features were developed and extracted per subject (Figure 3). These four features are calculated from the time and spectral domains for each inhale breathing sound event.…”

“…[1][2][3][4][5][6][7] Inspiratory breathing sounds can vary significantly across sleep and between subjects; in some cases the sounds may be soft (sound intensity < 40 dB), but in others it can be loud. [8][9][10][11][12][13][14][15][16] Intense breathing sounds are commonly referred to as snoring. 10,[13][14][15][16] The most accepted estimate for the prevalence of chronic snoring is 40% in adult men and 20% in adult women, although the variability is extremely large.…”

“…[8][9][10][11][12][13][14][15][16] Intense breathing sounds are commonly referred to as snoring. 10,[13][14][15][16] The most accepted estimate for the prevalence of chronic snoring is 40% in adult men and 20% in adult women, although the variability is extremely large. 16 Early work has shown a poor correlation between measured loudness of snoring and subjective appreciation by different observers.…”

“…It is recognized that to a large extent snoring is "in the ear of the beholder". 14 Several studies have addressed the issue of detection of snoring sounds from a recorded audio signal during sleep using signal processing and pattern recognition algorithms. 10,[17][18][19][20][21][22][23] Recently, we showed that audio-based features, extracted from audio recordings, can accurately detect, not only snoring sounds, but also sleep breathing sound events (intensity > 20 dB) even in a very quiet environment, with accuracy > 98%.…”

Is the population properly informed about sleep disorders?

“…Additionally, children do not always share a room with an adult who is aware of this symptom. The report from a roommate is important in recognizing this disease because the impact of snoring is primarily 'in the ears that hear it' 27 .…”