How voice picking stacks up against paper, RF scanning and Pick-to-Light

Posted by Tailar Kennedy on May 11, 2017 10:38:41 AM

How voice picking stacks up against paper, RF scanning and Pick-to-Light

When evaluating picking solutions for the warehouse, there are four main options that are often considered: voice, paper, RF scanning, and pick-to-light. Although each of these solutions have their own strengths, weaknesses, and ideal applications, they should all be considered when making a decision about future projects. Comparing the four solutions to each other, and evaluating what they will bring to your operation, is the best way to determine what will be the best fit for your operation. Below is a comprehensive look at the four solutions, and how they perform against each other.

Paper Picking

 Paper-based order picking, or label processing, is the process of completing warehouse procedures with the use of paper orders. Paper picking is typically coupled with after-the-fact data entry using desktop terminals. Associates perform warehouse tasks off of pick lists, put-away labels, printed VAS instructions, and other paper documents. Upstream processes (such as how the information is sorted on the documents), and downstream processes (such as scan and verify on a desktop terminal), directly impact paper/label processing’s performance and functionality.

 Paper/label processing is thought of as a good fit for smaller operations with relatively straightforward transaction requirements. Even operations that rely on RF scanning for the bulk of transactions usually employ paper/label processing for some functions. It can be purely a manual proposition or part of an automatic flow, such as a label case pick-to-belt, where the pick is confirmed by an in-line conveyor scan.

Voice vs. Paper Picking

 While paper picking is a great starting point for many smaller operations, it tends to be a barrier to large scale growth and improvement. Paper completely eliminates the ability for real-time visibility into inventory, employees, or systems. The entire process is held until the data entry process begins, and that process is prone to errors.

Additionally, having workers burdened with paper handling slows down the processes that are key to the functioning of your DC. Having to pick up and put down clipboards removes the workers attention from the task, and can lead to unwanted errors or mispicks.

Radio Frequency (RF) Scanning

 RF scanning terminals have long been considered a prerequisite for larger, more complex operations. However, RF scanning can be found in all different types and sizes of operations primarily due to direct support by most warehouse management systems (WMS). Even operations running non-RF enabled legacy fulfillment systems can turn to automated data collection software for this functionality.

RF scanning offers some distinct advantages over paper/label processing. It can provide positive verification that the warehouse associate is at the right location or picked the correct SKU through a barcode scan or key entry. Work can be pushed out to associates based on location and task priority instead of handed out from a manually managed queue. Transaction data is captured in real time as associates perform tasks. Furthermore, RF scanning makes some functions like multi-order cart selection possible or more practical than paper/label processing.

Voice vs. RF Scanning

 Prior to voice, no other technology had a greater impact on the evolution of WMS than mobile or RF scanners. While they are popular with many companies, RF and barcode scanners do have some drawbacks. Training on RF scanners can be extensive, with some operations requiring up to three weeks before workers are self-sufficient. Once fully trained, these workers are still distracted with something in their hands, and are unable to complete warehouse processes without picking up and putting down the scanner.

Additionally, maintenance costs for the devices can be high, as many workers drop or mishandle the scanners during use. This can lead to expensive screen or keyboard replacements, as well as the need for extra equipment to compensate for the damaged units.

Voice technology allows workers to complete tasks quickly and efficiently, with workers able to keep their hands and eyes free, and their attention on the project at hand. The voice picking process can cut the information exchange down to three steps (as seen below), which leads to a direct increase in picking speeds and productivity.

Voice vs RF scanning.png

Pick-to-Light (PTL)

 Pick-to-Light remains a popular selection technology due to its ability to support high pick rates and its ease-of-use. It is typically used in a zone-based, pick and pass flow where an associate scans a tote or carton barcode label. The PTL software activates light displays for every location that shows the required quantity needed for the tote or carton. The associate walks the zone, selecting SKUs and confirming picks by pressing display buttons. Pick quantities can be shorted or increased by button presses. Displays can also be provided to show SKU, order, or other relevant information. Some vendors even have LCD displays that show SKU pictures.

Also, as its name implies, PTL technology is about the order selection process. Unlike the other technologies discussed in this paper, it is not employed to drive other warehousing functions such as receiving, put-away, and cycle counting. This means any investment in the technology cannot be leveraged beyond the confines of the PTL module and order selection process.

Voice vs. PTL Picking

Pick-to-light presents some fit challenges that go beyond pick rates and raw productivity numbers. It is an inherently more costly and complex technology that typically requires a significantly higher start-up investment and a relatively rigid product flow. Totes and cartons are generally routed between fixed pick zones via a conveyor system. Managing workflow can be an ongoing issue, because of daily workload fluctuations between zones that result in bottlenecks in some and under-utilization in others. 

Voice offers much more flexibility to redeploy resources to match daily changes in overall workload on the warehouse floor. Furthermore, changing the configuration of a pick-to-light module can require additional changes to the light displays, communications backbone, and pick-to-light software as well as physical storage media and WMS changes. Reconfiguring pick modules supported by voice is a much simpler proposition that generally only requires labeling in addition to storage media and WMS changes.



  • Productivity - Voice is 10-15+% faster
  • Accuracy - Voice has 10-20 less errors per 1,000
  • Training - Voice reduces time by 50%
  • Issues:
    • Lack of real-time associate visibility and accountability
    • Lack of real-time inventory, people and system updates
    • Difficult to batch-pick
    • Data entry errors
    • Labor and materials cost to handle paper
    • Not hands or eyes free

RF Scanning:

  • Productivity - Voice is 15-25+% faster
  • Accuracy - Voice has 2-4 less errors per 1,000
  • Training - Voice reduces time by 50-65%
  • Issues:
    • Average 2-3 weeks of training for associate to be self-sufficient
    • Operator is distracted: data entry, read, scan
    • Saftey issus (head-down)
    • Not ergonomic
    • Not hands or eyes free
    • Battery issues
    • Risk of equipment damage


  • Productivity - Same
  • Accuracy - Voice has 2-4 less errors per 1,000
  • Training - Similar Training Effort
  • Issues:
    • Inflexible
    • Expensive to add additional SKUs
    • Can't efficiently manage two order selectors in one zone
    • Difficult to batch-pick
    • Sized based on SKUs vs. number of people on floor
    • Thousands of points of failure (we are talking about lights...)

Although each of these solutions has its merits, voice often out-performs the other options. With better productivity, accuracy, training time, and flexibility, voice can improve your warehouse while delivering an ROI in 9-12 months. If you have any questions about voice, or would like to consider voice for your operation, please contact us at or visit our website at


Topics: Voice