The assistive technology, Augmentative and Alternative Communication (AAC), refers to any mode of communication other than speech.
There are various options, including eye-gaze technology which uses a camera to capture eye movements that can control the mouse and perform clicks.
Although eye-gaze devices are still expensive, they have become more affordable and patients can apply for subsidies from the Assistive Technology Fund.
"An alternative for those who cannot afford Tobii (an eye-gaze device) is to get a free software called Web-Gazer, which uses the built-in camera in the computer to detect your eyes," said Mr Ivan Tan, senior manager of the SPD's Specialised Assistive Technology Centre.
"However, these built-in cameras are usually not very good. So, if your communication depends on it, you may get frustrated as it is not as accurate as Tobii."
For patients who expect to lose their voice at some point, there is also the option of voice banking.
This allows a person to record a set list of phrases with his voice, which is converted to a personal synthetic voice. This synthetic voice can be used in speech-generating communication devices.
Mr Tan knows of an Amyotrophic lateral sclerosis patient who recorded 6,000 phrases, which were then packaged into software in the United States.
He said she wanted to continue to "talk" to her two sons, who are studying in the United States, via Skype.
For patients who can move their head, Mr Tan suggested using a gyroscopic mouse that is mounted on a headband. It is easier to use this than the eye-gaze device as small movements of the head will direct the mouse, he said.
Today, electronic communication aids which allow people to use picture symbols, letters and words or phrases to create messages are increasingly used.
More AAC-related apps have been developed in the past three years for those who cannot express themselves but can move their limbs, said Khoo Teck Puat Hospital's senior speech therapist Chong Boon Keng.
An example is LetMe Talk, which uses text-to-speech technology. It allows users to line up images in a meaningful way and the app will then read out the row of images as a sentence. For instance, you can pick images for "I want", "to eat" and "bread".
As speech therapists, Ms Chong and her colleagues train patients and their caregivers to use such apps.
"We need to get them to be receptive to the idea of using apps to communicate. We will do role-play. We must make sure the patient can navigate the app."
Mr Jason Lim, a senior speech therapist at Changi General Hospital (CGH), said computer software and iPad apps allow patients with communication disorders to increase the amount of speech and language therapy they receive beyond their sessions with speech therapists.
These include alphabet boards, image pointer boards, and pen and paper.
Family members can create their own booklet or communication board by printing pictures on paper. "You have to first find photos and pictures. Some caregivers will give up if it is too much trouble," said Ms Chong.
Nevertheless, low-tech options are very practical and widely used.
Ms Chong said she had a patient with multiple system atrophy who did not own a tablet. "We used a booklet to communicate with her. We would point to a picture or a phrase in the booklet that indicated things like propping up, blanket or medication, and she would blink to indicate yes," she said.
Mr Lim said CGH recently treated a patient who had a large brainstem stroke and was unable to commu- nicate in any manner, apart from blinking and gazing with the eyes.
The locked-in syndrome leaves patients mentally aware but unable to move all voluntary muscles, except for the ones that control the eye movements. Mr Lim said: "With the help of our rehabilitation technician, we made eye-gaze boards out of cardboard and cus- tomised them with vocabulary that was relevant to the patient."