Methodological study on DPOAE measurement procedures

Otoacoustic emission (OAE) has an extraordinary potential as a tool for the assessment of temporary changes in the hearing, and hearing damage. The OAE provides valuable information about the state of the most vulnerable part of the hearing in a simple and non-intrusive manner. The purpose of the present study was to develop a method that can determine the OAE during recovery from intense sound exposure. This requires the method to be both fast and accurate, and not intervene the state of hearing during recovery. DPOAEs were measured with the ILO96 Research-
system from Otodynamics, using the operating mode called DPOAE macro. This mode allows the user to write a program (so-called macro) which defines the operations to be performed by the system. The main features of the DPOAE-macro mode are: (1) It allows to program up to 16 user-defined pairs of primaries f1 and f2; (2) measurements can be done in a loop mode during a time period programmed by the user; and (3) it is possible to program the level of the primaries L1 and L2, the frequency ratio f2/f1 and the averaging time per primaries presentation. The DPOAE-macro mode is suitable for the assessment of DPOAE recovery because the measurement process becomes highly automated, and data acquisition can be performed in a loop-mode without interruptions. The method developed was used in the assessment of risk of hearing damage from sound with different temporal characteristics (see other project). (Supported by FTP)