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Overtone Synthesizer
Overtones are multiples of a fundamental frequency. Some audio media have difficulty recording the upper octaves of the audio spectrum and thus are deficient in this sonic area. The Overtone Synthesizer effect is designed to help correct this type of audio anomaly. The Diamond Cut Overtone Synthesizer operates in the upper portion of the audio spectrum and is the compliment to the Sub-harmonic synthesizer. It can be used to add treble or “brilliance” to any recording. It can also be used to enhance the hissy – sibilant sounds sometimes missing from highly muffled forensics recordings. The Overtone Synthesizer takes audio signals in the treble portion of the spectrum and multiplies those frequencies times two and then adds them back into the systems output mix. When the “Cents” control is set for 0, this multiplication is exact. But, sometimes music sounds more natural when its overtones are not
perfect doubles. Thus, you can vary the “Cents” control up to +/- 200 cents (each semitone = 100 cents on a 12 tone scale of equal temperament). Higher than 0 Cent value settings will make the overtones sound sharper while values less than 0 will make them sound more flat.
The Overtone Synthesizer
You can choose the lowest frequency limit at which this process takes place via the “Frequency” control. A good frequency to start with is 5,000 Hz; adjust to your personal taste. You can also adjust the wet/dry mixture of the synthesized overtones with the original source signal by way of the “Overtone Level” control. As an example, if the Overtone Synthesizer frequency control is set to 4,500 Hz, frequencies are generated in the range of 9,000 Hz on up to the top end of the audio spectrum. These signals are then added back into the main signal pathway thereby re-constituting treble (or brilliance) which may be missing from a recording.
The Overtone Synthesizer includes the following user controls:
Forensics Note: The frequency range for this control in the Forensics version is wider and spans from 2,000 Hz to 9,000 Hz.
Note 1: For “Ultra Brilliant” treble effects, you can cascade two Overtone Synthesizers together in the Multifilter. Set the second one in the chain to half the frequency value of the first. For example, set the first one to 4,000 Hz and the second one to 8,000 Hz.
Note 2: Muffled Forensics recordings can be enhanced via the “Forensics Pseudo Sibilant (clarifier)” preset. Adjust the “Overtone Level” for the optimal result. Also, please refer to Note 3.
Note 3: The Overtone Synthesizer is limited for use on files that were sampled at 22.05 kHz and above. This fact is especially important in Forensics Audio applications which use lower sampling rates. If you desire to use it on files that were mastered on files that were recorded below 22.05 kHz, up-sample them to 44.1 kHz first and then apply the Overtone Synthesizer.
Note 4: Use of this effect in moderation is recommended in order to achieve the most natural sonic simulation of the upper end of the audio spectrum.
Overtones are multiples of a fundamental frequency. Some audio media have difficulty recording the upper octaves of the audio spectrum and thus are deficient in this sonic area. The Overtone Synthesizer effect is designed to help correct this type of audio anomaly. The Diamond Cut Overtone Synthesizer operates in the upper portion of the audio spectrum and is the compliment to the Sub-harmonic synthesizer. It can be used to add treble or “brilliance” to any recording. It can also be used to enhance the hissy – sibilant sounds sometimes missing from highly muffled forensics recordings. The Overtone Synthesizer takes audio signals in the treble portion of the spectrum and multiplies those frequencies times two and then adds them back into the systems output mix. When the “Cents” control is set for 0, this multiplication is exact. But, sometimes music sounds more natural when its overtones are not
perfect doubles. Thus, you can vary the “Cents” control up to +/- 200 cents (each semitone = 100 cents on a 12 tone scale of equal temperament). Higher than 0 Cent value settings will make the overtones sound sharper while values less than 0 will make them sound more flat.
The Overtone Synthesizer
You can choose the lowest frequency limit at which this process takes place via the “Frequency” control. A good frequency to start with is 5,000 Hz; adjust to your personal taste. You can also adjust the wet/dry mixture of the synthesized overtones with the original source signal by way of the “Overtone Level” control. As an example, if the Overtone Synthesizer frequency control is set to 4,500 Hz, frequencies are generated in the range of 9,000 Hz on up to the top end of the audio spectrum. These signals are then added back into the main signal pathway thereby re-constituting treble (or brilliance) which may be missing from a recording.
The Overtone Synthesizer includes the following user controls:
- Frequency: Range is 3,500 Hz to 9,000 Hz – This sets those frequencies above which are used to excite overtone generation. It is the “corner frequency” setting.
Forensics Note: The frequency range for this control in the Forensics version is wider and spans from 2,000 Hz to 9,000 Hz.
- Overtone Level: Range is -60 dB to + 10 dB – This sets the amount of the effect applied to the output.
- Output Level: Range is – 60 dB to +10 dB – This sets the overall output level of the effect, including both the basic signal as well as the overtones. Keep this control set such that the “Clip” LED does not illuminate.
- Sharp Cutoff Checkbox: This feature creates a very steep slope above the frequency setting providing a very high degree of discrimination of the higher frequencies being applied to the synthesizer. This feature can often decrease high frequency artifact generation by the synthesizer at the expense of a slightly lower level of smoothness of the frequency crossover transition of the system. In musical terms, it tends to add more “sweetness” to the top end when sharp cutoff is invoked. It is also useful in Forensics application by improving the sibilant sounds of the human voice without adding much distortion to the signal.
Note 1: For “Ultra Brilliant” treble effects, you can cascade two Overtone Synthesizers together in the Multifilter. Set the second one in the chain to half the frequency value of the first. For example, set the first one to 4,000 Hz and the second one to 8,000 Hz.
Note 2: Muffled Forensics recordings can be enhanced via the “Forensics Pseudo Sibilant (clarifier)” preset. Adjust the “Overtone Level” for the optimal result. Also, please refer to Note 3.
Note 3: The Overtone Synthesizer is limited for use on files that were sampled at 22.05 kHz and above. This fact is especially important in Forensics Audio applications which use lower sampling rates. If you desire to use it on files that were mastered on files that were recorded below 22.05 kHz, up-sample them to 44.1 kHz first and then apply the Overtone Synthesizer.
Note 4: Use of this effect in moderation is recommended in order to achieve the most natural sonic simulation of the upper end of the audio spectrum.