There are four energy sound types which are measured as a ‘snore map’:
- Type 1: A low-frequency single syllable snore.
- Type 2: Duplex sounds that have both low and middle frequencies.
- Type 3: Duplex sounds that have both low and high frequencies.
- Type 4: Triplex sounds that have low, middle and high frequencies.
Sound types can then be categorised according to two different snore patterns:
- Simple waveform snores: This pattern is normally characterised as a quasi-sinusoidal waveform with virtually no secondary internal oscillations (i.e. a range of variant sounds – a frequency range of 1 to 3 peaks - as a result of back and forth movement in a regular rhythm, mainly involving the tongue). This pattern normally has a high frequency due to tissue oscillation (i.e. vibration of the airway walls occurs around a neutral position) without actual closure of the airways being experienced.
- Complex waveform snores: This pattern usually involves a momentary closure of the airways as a result of ‘airway wall collision’. This pattern is characterised by equally-spaced, repetitive sounds (with multiple peaks) and is described as having a comb-like spectrum. Complex waveform snores are associated with palatal snores (loud vibrations involving the soft palate, uvula and back of the tongue result in airway closure).
from here