Scope and object This part of IEC 62127 specifies methods of use of calibrated hydrophones for the measurement in liquids of acoustic fields generated by ultrasonic medical equipment operating in the frequency range up to 40 MHz. The objectives of this standard are: ?C to define a group of acoustic parameters that can be measured on a physically sound basis; ?C to define a second group of parameters that can be derived under certain assumptions from these measurements@ and called derived intensity parameters; ?C to define a measurement procedure that may be used for the determination of acoustic pressure parameters; ?C to define the conditions under which the measurements of acoustic parameters can be made in the frequency range up to 40 MHz using calibrated hydrophones; ?C to define procedures for correcting@ for limitations caused by the use of hydrophones with finite bandwidth and finite active element size. NOTE 1 Throughout this standard@ SI units are used. In the specification of certain parameters@ such as beam areas and intensities@ it may be convenient to use decimal multiples or submultiples. For example beam area may be specified in cm2 and intensities in W/cm2 or mW/cm2. NOTE 2 The hydrophone as defined may be of a piezoelectric or an optic type. The introduction however implies that optical hydrophones are not covered.