Excellent agreement for mouth pressure measurements has been reported between the portable mouth pressure metre and laboratory standard pressure transducers by Hamnegard et al. (1994), and these authors maintain that this portable device is both precise and accurate for normal individuals and patients. The participants were encouraged to make a maximal effort for 2–3 s, and verbal encouragement was given to help them perform maximally. A minimum of five and a maximum of ten technically satisfactory measurements were conducted, and the highest of three measurements with 5% variability or within a 5 cm