Preparing loop-backMeasurement 3: Measuring using loop-back
This chapter assumes that you have performed the measurements described above. The main purpose of the loop-back is to determine the correct initial time delay of the system being measured (e.g. the distance between the loudspeaker and the microphone). Most sound cards do not have a constant time difference in start of playback and record, it is different from one measurement to another. This makes it impossible to find the initial time delay with the usual measurement method, but this is easily detected if using the loop-back.
When using a loop-back it is also possible to detect errors in the measurement caused by non-continuous play or record. This is usually a problem only for slow PC’s, but can occur if you run other tasks on your PC while performing a measurement. If such an error is detected the measurement will be repeated and a warning is given in the status bar.