A Full Frequency Masking Vocoder for Legal Eavesdropping Conversation Recording

TL;DR

This paper introduces a vocoder that uses full frequency masking and spectral filling to improve bandwidth efficiency while maintaining intelligibility, specifically designed for legal eavesdropping of long conversations.

Contribution

It proposes a novel vocoder design based on psycho-acoustic principles, combining full frequency masking with spectral filling via beta distribution, optimized for covert communication.

Findings

Effective bandwidth reduction while preserving speech intelligibility

Utilizes psycho-acoustic masking characteristics for vocoder design

Suitable for long-duration legal eavesdropping applications

Abstract

This paper presents a new approach for a vocoder design based on full frequency masking by octaves in addition to a technique for spectral filling via beta probability distribution. Some psycho-acoustic characteristics of human hearing - inaudibility masking in frequency and phase - are used as a basis for the proposed algorithm. The results confirm that this technique may be useful to save bandwidth in applications requiring intelligibility. It is recommended for the legal eavesdropping of long voice conversations.