Acoustic research for telecoms: bridging the heritage to the future

Abstract

In its early age, telecommunication was focused on voice communications, and acoustics was at the heart of the work related to speech coding and transmission, automatic speech recognition or speech synthesis, aiming at offering better quality (Quality of Experience or QoE) and enhanced services to users. As technology has evolved, the research themes have diversified, but acoustics remains essential. This paper gives an overview of the evolution of acoustic research for telecommunication. Communication was initially (and for a long time) only audio with a monophonic narrow-band sound (i.e. [300–3400 Hz]). After the bandwidth extension (from the wide-band [100–7000 Hz] to the full-band [20 Hz–20 kHz] range), a new break was the introduction of 3D sound, either to provide telepresence in audioconferencing or videoconferencing, or to enhance the QoE of contents such as radio, television, VOD, or video games. Loudspeaker or microphone arrays have been deployed to implement “Holophonic” or “Ambisonic” systems. The interaction between spatialized sounds and 3D images was also investigated. At the end of the 2000s, smartphones invaded our lives. Binaural sound was immediately acknowledged as the most suitable technology for reproducing 3D audio on smartphones. However, to achieve a satisfactory QoE, binaural filters need to be customized in relation with the listener’s morphology. This question is the main obstacle to a mass-market distribution of binaural sound, and its solving has prompted a large amount of work. In parallel with the development of technologies, their perceptual evaluation was an equally important area of research. In addition to conventional methods, innovative approaches have been explored for the assessment of sound spatialization, such as physiological measurement, neuroscience tools or Virtual Reality (VR). The latest development is the use of acoustics as a universal sensor for the Internet of Things (IoT) and connected environments. Microphones can be deployed, preferably with parcimony, in order to monitor surrounding sounds, with the goal of detecting information or events thanks to models of automatic sound recognition based on neural networks. Applications range from security and personal assistance to acoustic measurement of biodiversity. As for the control of environments or objects, voice commands have become widespread in recent years thanks to the tremendous progress made in speech recognition, but an even more intuitive mode based on direct control by the mind is proposed by Brain Computer Interfaces (BCIs), which rely on sensory stimulation using different modalities, among which the auditory one offers some advantages.