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1 Clinical Science Centre, and 3 Aintree Chest Centre, University Hospital Aintree, Liverpool, and 2 Dept of Computer Science, University of Manchester, Manchester, UK
CORRESPONDENCE: T. M. Jones, Dept of Otolaryngology, Head and Neck Surgery, University Hospital Aintree, Long Lane, Liverpool L9 7AL, UK. Fax: 44 1515295263. E-mail: terryjones@doctors.org.uk
Keywords: Acoustic analysis, palatoplasty, sleep, snoring
Received: September 9, 2004
Accepted January 26, 2005
To investigate the effectiveness of palatal surgery for nonapnoeic snoring, 35 patients were block randomised to undergo one of two different palatoplasty procedures. Patients were admitted pre-operatively for audio recording of snoring sound and video recording of sleeping position, and between 1.0 and 4.1 months (mean 2.5) and between 5.9 and 17.5 months (mean 9.7) post-operatively. Sound files, comprising the inspiratory sound of the first 100 snores whilst sleeping in a supine position, were analysed using specifically designed software.
Snore duration (s), loudness (dBA), periodicity (%) and energy ratios for the frequency bands 0200 Hz, 0250 Hz and 0400 Hz were calculated. Subjective outcomes were noted. Operation type, body mass index, age, peak nasal inspiratory flow rate, Epworth sleep score and alcohol intake were considered as confounding variables.
No patient was cured from snoring. Paired t-test analysis demonstrated statistically significant changes between pre- and early post-operative recordings for snore periodicity and energy ratios in the frequency ranges 0200 Hz, 0250 Hz and 0400 Hz.
In conclusion, only the 0250-Hz energy ratio measurements maintained a statistically significant improvement at the time of the late post-operative recording, despite an obvious drift back to pre-operative levels. No confounding variables were identified. The subjective and objective results correlated poorly. Post-operative changes in the acoustic parameters of snoring sound, following palatal surgery, are demonstrable but short-lived.
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