LENA works best when the device is turned on first thing in the morning and captures the child's language environment all day. After 16 hours, it will turn itself off.  That's why we say:

• Turn it on
• Put it on
• Leave it on

LENA requires at least 9.5 hours of data with no pauses longer than 60 minutes to display daily totals and percentiles, and for the LENA Day to be eligible to earn stars. A shorter LENA Day will display hourly data only.