of the larynx (i.e. muscle movement of the larynx), an individual is categorized under a high or low vocalizer depending on how much muscle movement the muscles in the larynx undergo during silent reading. Regulation of speech intensity Often in both high and low vocalizers, the rate of speech is constantly regulated depending on intensity/volume of words (said to be affected by long delays between readings) and increasing the delay of speech and hearing ones' voice is an effect called “delayed auditory feedback”. Increasing the voice intensity while reading was found to be higher in low-vocalizers than high-vocalizers. It is believed that because high-vocalizers have greater muscle movement of the larynx during silent reading, low-vocalizers read louder to compensate for this lack of movement so they can understand the material. When individuals undergo “feedback training”, where they are conscious of these muscle movements, this difference diminishes. Role in articulation Articulation during silent speech is important, though speech is not solely dependent on articulation alone. Impairing articulation can reduce sensory input from the muscle movements of the larynx to the brain to understand information being read and it also impairs ongoing speech production during reading to direct thinking. Words that are of high similarity minimize articulation, causing interference, and may reduce subvocal rehearsal. As articulation of similar words is affecting subvocalization, there is an increase in acoustic errors for short-term memory and recall. Impairing or suppressing articulation causes a greater impact on performance. An example of articulation suppression is repeating the same word over many times such as 'the' and attempting to memorise other words into short-term memory. Even though primary cues may be given for these words in attempt to retrieve them, words will either be recalled for the incorrect cue or will not be recalled at all. Schizophrenia and subvocalization People with schizophrenia known to experience auditory hallucinations could show the result of over-activation of the muscles in the larynx. Using an electromyography to record muscle movement, individuals experiencing hallucinations showed greater muscle activation before these hallucinations occurred. However, this muscle activation is not easily detected which means the muscle movement must be measured on a wider range. Though a wider range is needed to detect the muscle movement, it is still considered as subvocalization. Much more research is needed to link subvocalization with hallucination but many schizophrenics report "hearing voices" (as hallucinations) coming from their throat. This small