Most hearing aid models that are sold today are digital, meaning incoming sound is converted into a digital signal, processed using mathematical equations then converted back into sound. This allows the hearing aid to divide sound into many different frequency regions and amplify each region individually for a more accurate correction of your hearing loss. This processing within hearing instruments enables different amounts of amplification for soft, moderate, and loud sounds; therefore a manual volume control is not necessary. Digital sound processing enables very complex manipulation of sound, (see hearing aid technology).
Digital hearing aids are programmable, meaning the hearing instrument settings can be precisely fine-tuned and special features can be customized for each wearer by an audiologist, using hearing aid software on a computer. If your hearing changes the digital hearing aids are simply re-programmed.