Toshiba has developed a technology capable of precisely distinguishing the voices of individual speakers in real time, even when multiple persons are speaking at the same time.

Typically, voice recognition reliability falls off when multiple people speak simultaneously. While technologies have been developed for separating simultaneous speech, the acoustic characteristics of locations where conversations take place and recording environment factors, such as the positioning of the speakers, have required provision of dozens of minutes of recordings to realize training for optimal separation.

Toshiba claims that its new technology achieves precise, real-time identification of speakers and separate voice capture, even when many voices are trying to be heard, and delivers high-precision recognition and transcription of each speaker, using a microphone array embedded in a single sound input device.

High-precision transcription alleviates the need for manually keeping minutes in business meetings, and allows an increased focus on analysis of customer opinions and the improvement of staff manuals. Transcriptions of meetings with customers from overseas can also be used for automatic translation systems.

A problem with previous sound-source separation systems is that they require many minutes of pre-recorded speech for system training in order create a sufficiently precise separation filter for each speech source (person). Toshiba's method replaces this time-consuming direct learning for filter creation with learning of the spatial characteristics representing speaker position information from the positioning of the microphones. This achieves high-performance separation supported by continuous filter updates according to the environment, and approximately double the separation precision of previous techniques. Toshiba says that when separating simultaneous speech of two speakers, the amount of suppression of the of the second person's speech was improved from 3 to 9 dB - an approximate doubling.

In operation, the new system rapidly determines the relative positioning of speakers through matching an association table for sound direction to the time difference at which sound arrives from speakers attached to each microphone. This technique allows the capture and separation of each individual's voice, even when there are simultaneous utterances and without any previous recordings at the location.

Toshiba keeps working on the new technology, and plans to include it to its 2017 RECAIUS cloud-based service that supports various human activities for understanding the intentions of humans in audio and visual recordings.