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Background
Published in Russ Martin, Sound Synthesis and Sampling, 2012
Musical pitch is divided into octaves, and each octave represents a doubling of frequency. Thus A4 has a frequency of 440 Hz, whereas A5 has twice this frequency: 880 Hz. A3 has half the frequency: 220 Hz. Octaves are normally split into 12 parts, and the intervals are called semitones. The relationship between the individual semitones in an octave is called the scale. The table shows the equal tempered scale, where the intervals between the semitones are all the same: many other scalings are possible. Since there are 12 tones, and the frequency doubles in an octave interval, the semitone intervals in an equal tempered scale are each related by the 12th root of two, which is approximately 1.059,463. Semitones are split up into 100 cents, but most human beings can only detect changes in pitch of 5 cents or more. Cent intervals are related by the 1200th root of 2, which is approximately 1.00,057,779. As an example of what this represents in terms of frequency: for a A5 note of 880 Hz, a cent is just below 0.51 Hz, and thus 5 cents represent only 2.5 Hz!
Pitch Shift
Published in Alexander U. Case, Sound FX, 2012
That is only half the story. The effect is taken to the next level courtesy of some pitch shifting. Shift each of the delayed signals ever so slightly, and the mono source material becomes a much more interesting loudspeaker creation. Detune each delay a nearly imperceptible amount, maybe 5–15 cents. This is not a significant pitch change. An octave is divided into twelve half steps, representing adjacent keys on a piano or adjacent frets on a guitar. Each half step is further divided into 100 equal pitch increments, called cents. The pitch shifting called for in the spreader, then, is just 5 to 15% of a half step — all but imperceptible except to the most trained listeners. The goal of the spreader is to create a stereo sort of effect. As a result, one seeks to make the signal processing on the left and right sides ever so slightly different from each other. Just as unique delay times are selected for each side of this effect, choose different pitch shift amounts left and right as well — maybe the left side is shifted down 8 cents while the right side is shifted up 8 cents.
MIDI and synthetic audio control
Published in Francis Rumsey, Desktop Audio Technology, 2003
The tuning standard assumes that any note on a sound generator can be tuned over the entire range 8.1758 Hz to 13 289.73 Hz. It then allows individual notes’ tuning to be adjusted in fractions of a semitone above a conventional MIDI note’s pitch (which would be based on the equal temperament convention). A semitone is divided into 100 cents. A cent is one hundredth of a semitone, and as such does not represent a constant frequency increment in hertz but represents a proportion of the frequency of the note concerned. As the pitch of the basic note rises, so the frequency increment represented by a cent also increases. Two MIDI data bytes are used to indicate the fraction of a semitone above the basic note pitch, so the maximum resolution possible is 100 cents/214 which equals 0.0061 cents.
Multilingual News–An Investigation of Consumption, Querying, and Search Result Selection Behaviors
Published in International Journal of Human–Computer Interaction, 2020
Chenjun Ling, Ben Steichen, Silvia Figueira
As previously mentioned, all participants were recruited through the FigureEight crowdsourcing platform. To minimize low quality entries, we took three quality control steps for all studies. The first step was to recruit only Tier 3 participants (the highest level on FigureEight). Secondly, the question choice options were shown randomly, and participants who always selected the same option number (e.g. always the first option) were removed. The last step consisted of a security check question that was added in the middle of the task questions. As previously mentioned, the question “Please select the option that says, ‘I am multilingual.’” was asked in the Phase 1 consumption survey. In phase 2, some of the tasks contained a check box stating “PLEASE CHECK THIS BOX (this confirms that you are not a robot or spammer)”. We manually filtered out the participants who selected the wrong options in the security check questions or showed obvious bias selection patterns. For the survey in phase 1, each participant was paid 15 cents per survey, with an average completion time of 4 minutes. In phase 2, each task-based study paid 25 cents per participant, and the average finishing time was 9 minutes.