FDA has approved the first implantable device for adults with severe or profound sensorineural hearing loss of high-frequency sounds in both ears, but who can still hear low-frequency sounds with or without a hearing aid. The Nucleus Hybrid L24 Cochlear Implant System, manufactured by Australian firm Cochlear Ltd., combines the functions of a cochlear implant and a hearing aid.  The technology includes an external microphone and speech processor that picks up sounds from the environment and converts them into electrical impulses.  The impulses are transmitted through small implanted electrodes to create a sense of sound that the user learns to associate with the mid- and high-frequency sounds they remember.  Of the 50 people studied in the clinical trial, 68% experienced some adverse events such as low-frequency hearing loss, ringing in the ear, electrode malfunction and dizziness.  However, the FDA determined that the overall benefits outweighed this risk for people who do not benefit from traditional hearing aids.  
[1]  FDA News Release, "FDA approves first implantable hearing device for adults with a certain kind of hearing loss" (March 20, 2014).

A new study appearing in Pediatrics reports that some "sleep machines" marketed to soothe babies to sleep may generate enough noise to damage a baby's hearing.  "Sleep machines" are intended to lull babies to sleep with white noise, nature sounds, a heartbeat, or other constant sounds.  But in tests of 14 sleep machines, researchers found all were capable of breaking the noise limit recommended for hospital nurseries (50 decibels) and some were capable of decibel levels that exceed the limit for recommended workplace levels (85 decibels).  

Furthermore, some researchers question whether exposing infants to constant sound all night could have other long-term effects on development.  Animal research has found that prolonged exposure to white noise during infancy can alter the brain's processing of sound and the animal's behavior.  Because longer-term consequences are unknown, researchers suggest that before buying a sleep machine parents try to soothe babies to sleep in other ways like warm baths and old-fashioned lullabies. And, if using a sleep machine, Dr. Ronald Hoffman of the New York Eye and Ear Infirmary of Mount Sinai recommends keeping the volume low and placing the machines across the room from baby's crib -- advice which is absent from the products' packaging.    

[1] Pediatrics (online March 3, 2014 and in print April 2014)
[2] NIH HealthDay, "Baby  'Sleep Machines' Could Damage Hearing, Study Suggests" (March 3, 2014).