• AAC devices help those with speech difficulties communicate with others.Indeed/Photodisc/Getty Images
  
  Augmentative and Alternative Communication devices---also known as AAC or text-to-speech devices---are tools that help those with severe speech impediments to express what they mean to say. There are several digital-tech AAC devices available on the market from a wide variety of specialist sellers; every device is different in its price, technology and usability.
  
  

DynaVox Maestro

• DynaVox says itself that the Maestro is "designed to meet a broad range of needs based on one's age and ability." The AAC device boasts an easy-to-use interface and navigation system. The software and hardware are also built to work in conjunction with each other, making page selection and writing quicker and more efficient. The device also makes use of Series 5 Software, which uses rate-enhanced phrase predictors to ensure that you don't have to type out every single word individually or wait too long for a predictor to offer you options. The audio output voice is clear, easy to understand and naturally sounding, and the Maestro also allows users to manage their files and MP3s. This particular AAC also offers bilingual options and is written and spoken to industry standard English, French and Spanish. See the DynaVox Maestro webpage for product specification PDFs and prices.
  
  

PRC Essence Pro

• The Essence Pro describes itself on the PRC website as "PRC's most advanced AAC device and Windows XP-based computer in one---fast processing speed and plenty of computing power for greater communication results." What's quite unique about this product is that it also allows for head-pointing, something that certain disabilities and wheelchair users require. The head-pointing function requires no external pointing devices and is implemented by Tracker Technology. An optional ECOpoint function also allows the user to use an integrated eye-gaze system with the Essence Pro. See the website for further price information and a printer-friendly info-and-spec sheet.
  
  

ZYGO Industries Polyana JT with Persona

• The main attraction of the Polyana JT is its price. At a significantly lower rate than most AACs, this particular text-to-speech device is cheaper due to its setup; essentially, the device is a Windows CE mini-laptop that contains a built-in Persona communication program. The size of the piece is 8.9 x 6.5 x 1.4 inches and weighs 1.8 lbs, while the speech output uses a Neo Speech synthesizer and sounds like a natural American-English voice. There is also a large enough memory to store scripts and pre-made documents ready to convert into speech and two USB ports to connect to external inputs. The device can be bought with wheelchair attachment and carry-cast additions; see the ZYGO website for further information.