Palatal snoring produces explosive peaks of sound at very low frequency (approximately 20 Hz). Using a digital sound trace a ratio of peak amplitude to root mean square amplitude can be calculated. This Peak Factor Ratio is significantly higher for palatal snores than non-palatal snores (P < 0.01). This acoustic method will be useful for selecting patients for palatal surgery as it is non-invasive and could be used in a home monitor.

Snoring is a common disorder and may lead to the development of Obstructive Sleep Apnoea (OSA) with its associated hazards. Differentiation of patients with OSA from patients with simple snoring is crucial to the ENT surgeon before selecting treatment. This study aimed to assess the reliability of the Epworth Sleepiness Scale (ESS) to screen for OSA among snorers. Forty-six patients referred for treatment of snoring were studied. Each patient completed the ESS questionnaire and subsequently underwent a hospital sleep study. The ESS scores did not correlate with the apnoea/hypopnoea indices calculated from the sleep studies (correlation coefficient 0.12). The lack of correlation is mainly because simple snorers can also suffer from excessive daytime sleepiness, due to an unclear mechanism. The ESS is a useful questionnaire for assessing disability as a result of snoring but it is of no value in distinguishing simple snorers from patients with OSA.

The differentiation of palatal from non-palatal snoring is very important for ENT surgeons trying to determine whether palatal surgery would be curative. At present sleep nasendoscopy is the accepted method. Palatal vibration produces marked modulation of sound loudness at low frequency (below approximately 100 Hz). We calculate a crest factor for the sound waveform (ratio of peak to root mean square (rms) value in any given epoch), as a measure of the degree of modulation. Free-field snore sounds were recorded from 11 supine adult patients under intravenous sedation (midazolam), using a digital tape recorder. Recordings were transferred to a PC (sampling frequency 11 kHz), and analysed using code written by us. Direct visual confirmation of the site of snoring was gained from simultaneous sleep nasendoscopy, taken as the gold standard. In six patients the dominant site was the soft palate. The non-palatal group (five patients) comprised one epiglottic, two hypopharyngeal and two tongue base snorers. The crest factor was found to be significantly higher for palatal snorers (p < 0.01, Student-t or Mann-Whitney tests). Furthermore, palatal could be distinguished from non-palatal snorers on the basis of crest factor alone in all 11 cases, making this a promising non-invasive diagnostic technique.

This study was designed to evaluate objectively the clinical effectiveness of surgery for snoring and to compare the results of conventional uvulopalatopharyngoplasty (UPPP) and laser assisted uvulopalatoplasty (LAUP) in the treatment of snoring. Patients who had been referred for investigation and treatment of their snoring were randomly allocated to receive either UPPP or LAUP. Forty-seven patients with confirmed palatal flutter had surgery and all of them had a preoperative and postoperative objective assessment of their snoring loudness and duration in the home. The recording device (Snore Box) is simple for the patient to operate, portable with a built in microphone, and able to produce objective results, which can be automatically analysed. Of the 38 patients, who had technically valid recordings, 22 underwent LAUP and 16 UPPP. Overall the mean postoperative Snore Index (SI) was less than the preoperative SI (P < 0.0001), the average difference being 78.2 snores/h. There was no significant difference between the LAUP and UPPP regarding the fall in the SI. This study is the first objective comparative study to demonstrate the effectiveness of snoring surgery.

Sleep nasendoscopy can be used to identify the site of snoring but questions remain about how well a short assessment during drug-induced sleep reflects the natural condition. To investigate the uniformity of snoring during natural sleep we studied five patients (three men, two women) referred by their GPs for treatment of their snoring. A digital audio tape recorder captured the free-field snore sound at different times of night in hospital. Acoustic Crest Factor values were calculated on the 15 recordings made, having previously demonstrated that high crest factor values distinguish palatal from non-palatal snoring at sleep nasendoscopy. Some recordings showed reproducibility, but others showed substantial changes between recordings an hour apart. We infer that the snoring mechanism may change in some individuals during the night, with or without a change of snore site. We conclude a single recording, as in sleep nasendoscopy, may not be representative.