Acoustic method for assessment of urethral obstruction: a model study

Perineal noise recording as a non‐invasive diagnostic method of urinary bladder outlet obstruction: a study in polyvinyl alcohol and silicone model urethras

“…The power spectrum of each recording was quanti¢ed by its essential frequency F calculated as the sum of frequencies (f) times the corresponding power [P(f)] divided by the sum of the power, for frequencies between 100 and 1,000 Hz. In the literature this essential frequency has also been referenced to as the Mean Power Frequency [Teri˛, 1991].…”

“…These turbulences cause pressure £uctuations on the wall of the urethra that can be recorded as noise transmitted via the urethra to the skin. In silicone [Teri˛, 1991] or latex [Tobin and Chang, 1976;Jones and Fronek, 1987] test tubes it has been shown that pressure £uctuations are indeed induced by £ow and that the power spectrum of the recorded noise depends among others on the degree of obstruction applied.…”

“…Another decade later, experimental [Koiso et al, 1991;Teri˛, 1991] and clinical studies [Koiso et al, 1991;van Koeveringe and van Mastrigt, 1991] were published on the relation between noise recordings and bladder outlet obstruction. In the same period of time, studies were done on vascular murmurs caused by stenoses, a method referred to as phonoangiography [Lees and Forbes Dewey, 1970;Duncan et al, 1975;Tobin and Chang, 1976;Fredberg, 1977;Pitts and Forbes Dewey, 1979;Jones and Fronek, 1987].…”

“…We analysed the recordings by calculating the average noise-amplitude of the recorded noise signals and the essential frequency of its power spectrum. For a comparison with earlier work [Teri˛, 1991] we repeated the measurements in two silicone tubes with di¡erent diameters.…”

“…In the same period of time, studies were done on vascular murmurs caused by stenoses, a method referred to as phonoangiography [Lees and Forbes Dewey, 1970;Duncan et al, 1975;Tobin and Chang, 1976;Fredberg, 1977;Pitts and Forbes Dewey, 1979;Jones and Fronek, 1987]. It was shown that based on either the mean power frequency [Teri˛, 1991], the break frequency of the noise spectrum [Tobin and Chang, 1976;Fredberg, 1977;Jones and Fronek, 1987], the shape of the recorded noise signal [Koiso et al, 1991], or a combination of the average power amplitude in a speci¢c frequency band with the simultaneously measured £ow rate [van Koeveringe and van Mastrigt, 1991] diagnosing arterial stenosis and bladder outlet obstruction could be possible.…”