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An Introduction to Digital Audio and Video
Published in Francis Rumsey, John Watkinson, Digital Interface Handbook, 2013
Francis Rumsey, John Watkinson
As sound causes no overall air movement, the average velocity of all sounds is zero, which corresponds to silence. As a result the bi-directional air movement gives rise to bipolar signals from the microphone, where silence is in the centre of the voltage range, and instantaneously negative or positive voltages are possible. Clearly the average voltage of all audio signals is also zero, and so when level is measured, it is necessary to take the modulus of the voltage, which is the job of the rectifier in the level meter. When this is done, the greater the amplitude of the audio signal, the greater the modulus, and so a higher level is displayed.
Physical Programming for Blind and Low Vision Children at Scale
Published in Human–Computer Interaction, 2021
Cecily Morrison, Nicolas Villar, Alex Hadwen-Bennett, Tim Regan, Daniel Cletheroe, Anja Thieme, Sue Sentance
Each pod is a statement in the program. Learners can build up a range of program flows with different pods. In this new version of Torino, in addition to play, rest, and loop pods, there is also selection (if then), and merge (end if). Each pod has a number of connectors and cables that allow them to be plugged together to define the structure of the program. Pods plug into one of four jacks on the main unit (Hub), representing the logical starting point of the program with each connection point the start of a thread. For example, Figure 2 shows a program with three concurrent threads. The first thread will play a single sound, and then will enter a loop that will repeat the action of playing a rest (silence) followed by a sound. A second thread will play three sounds in sequence. A third thread will play either a sound or a rest, depending on the outcome of a conditional statement.