Speech synthesizers are text-to-speech systems used with computers. It can be a card that is inserted into the computer, a box attached to the computer by a cable, or software that works with the computer's sound card. Speech synthesizers are programmed to include all the phonemes and grammatical rules of a language, allowing words to be pronounced correctly although names and compound words can cause problems because they often contain unusual spellings and letter combinations. Some synthetic speech sounds robotic; however, more and more new products sound almost human. Prices range from approximately $150 to $1,000, and software synthesizers are routinely included with the purchase of a screen reader.