Pick to Voice System (PTV)
Consists of a portable terminal that uses voice commands to guide the operator and uses voice recognition to obtain information on the realized task.

Pick to Light system (PTL)
Consists of visual commands to guide operator and the operator uses buttons to report the realized task.

An operator´s crucial resource are his/her hands. The PTL systems are based on operators´ eyes. The PTV systems are based on ears and memory of the operator. The visual information is captured as required by the operator and he/she can select relevant information.

The audible information es lost if not captured by the operator and must be requested again. Another human characteristic is that individual voice can change. These factors must be kept in mind in the evaluation of a human interface.

The price for a PTL system grows as the supply locations number grows and the price does not depends on the number of operators. On the other hand the price of a PTL system grows with the number of operators and does not depends on the locations number.