That is what encryption is for. You only need to secure the voice until it can be encrypted.
Worth noting that the feeling of privacy is a lot about perception. People feel better if they know those they see around them cannot hear their private convo. That is why they speak softly and put their hands to their mouth talking in public places (the other part was to boost the signal, before the advent of differential microphones).
Don't get me wrong, I most definitely agree external cancellation is terrific, be it active or passive. In the passive realm people use traditional dampening materials, as well as MPPs (micro-perforated plates) in certain industrial applications.
Worth noting that the feeling of privacy is a lot about perception. People feel better if they know those they see around them cannot hear their private convo. That is why they speak softly and put their hands to their mouth talking in public places (the other part was to boost the signal, before the advent of differential microphones).
Don't get me wrong, I most definitely agree external cancellation is terrific, be it active or passive. In the passive realm people use traditional dampening materials, as well as MPPs (micro-perforated plates) in certain industrial applications.