infrasonic /in-frə-sonˈik/ (acoustics)

1. (of frequencies) below the usual audible limit
2. Of, using or produced by infrasonic vibrations or pressure waves

inˈfrasound noun

• lay bare
• lay before
• lay brother
• lay brothers
• lay by
• lay-by
• lay-bye
• lay-bys
• lay by the heels
• lay claim to
• lay clerk
• lay clerks
• lay communion
• lay-day
• lay-days
• lay down
• lay-down
• lay down one's arms
• lay-downs
• lay down the law
• layer
• layer cake
• layered
• layering
• layerings