Application in mind is the vINa, where if acoustic signal strength is above a threshold, gets priority over the pickup sound which will kick in only when the acoustic source is too feeble , especially the unplucked sound emission on dampening phase of the string vibration!
Needs to be real time!
Designing a signal strength-based acoustic mixer with priority
Creating a mixer that automatically switches between two microphones based on signal strength and priority involves several key components and concepts:
1. Automatic microphone mixing
Automatic mic mixers analyze the input level of each microphone and only open the channels that are actively receiving audio signals that exceed a set threshold.
When the signal level from a microphone surpasses the threshold, its channel opens, allowing the audio to pass through.
When the audio signal drops below the threshold, the channel closes or is attenuated by a predetermined amount.
2. Priority mixing
Many automatic mixers offer a "priority" function that allows you to assign a hierarchical order to the microphones.
If multiple microphones exceed the threshold simultaneously, the mixer will prioritize the audio from the higher priority source.
This can be achieved by momentarily attenuating or muting the lower priority microphones, or by favoring the higher priority signal in the mix.
3. Threshold adjustment
The effectiveness of signal strength-based mixing hinges on setting the correct threshold level for each microphone.
If the threshold is set too low, the mixer may pick up unwanted background noise and open channels unnecessarily.
If the threshold is set too high, the mixer may miss subtle audio cues or fail to switch to the active microphone in a timely manner.
Modern automatic mixers often incorporate "adaptive threshold" or "noise floor tracking" features, which dynamically adjust the threshold level based on the ambient noise in the room, enhancing performance in varying environments.
4. Attenuation and other features
To prevent abrupt transitions when channels open and close, automatic mixers may include "off attenuation" and "hold time" controls, allowing for smoother fades and preventing the mixer from shutting off between words or phrases.
"Number of Open Microphones (NOM)" controls can also be used to manage the total number of open channels and further control feedback.
5. Potential considerations
Microphone placement: For optimal performance, follow the "3:1 rule" where possible, ensuring that the distance between microphones is at least three times the distance between the primary source and the nearest microphone, to minimize phase issues and improve clarity.
Speech vs. music: Mixing for speech may require different settings than mixing for music, as the dynamic range and transients can differ significantly.
By implementing these principles and considering the nuances of your specific application, you can create a robust and effective signal strength-based acoustic mixer with priority switching to enhance audio clarity and control.