MSMA (monosodium methanearsonate) is an arsenic-based grass killer. It kills grassy weeds such as crabgrass and goosegrass without harming most turfgrasses. It contains organic arsenic that, according to the University of Tennessee Extension, is less harmful than aspirin.
There are several styles of hearing aids available, from the smallest - Invisible in the Canal (IIC) to the largest and strongest - Power Behind the Ear (BTE), and the very popular Receiver in the Canal (RIC) - made to fit most hearing losses while remaining nearly unseen.
There are other types of hearing aids for specific types of hearing loss. For example, one type uses a bone vibrator for people without an ear canal or outer ear. Others may attach to eyeglasses. Ask about other devices that may make your hearing aids work better in certain settings.