AISense, one of the key players in the audio transcription market, has announced an injection of $10 million of funds.

Its core product is Otter, which debuted at Mobile World Congress in 2018 and has already become popular among students and journalists. Otter's software is accessed via a mobile app and used for transcribing conversations.

The AISense investment brings the total amount of venture capital the San Francisco company has raised to $23 million. It was led by Japanese mobile phone giant NTT Docomo with support from Fusion Fund, GGV, Dragon Dragon Fund, Duke University Innovation Fund, Harris Barton Asset Management, Slow Ventures, and others.

Otter distinguishes speakers by generating a unique print for each person’s voice, a process it calls called diarisation. The transcripts are processed in the cloud and available via the web or services like Dropbox.

Among Otter’s many innovative features is a word cloud at the top of each recording which lists the most popular words used during the recording. The conversations are also searchable and can be archived in different formats.

AISense, which Fortune Business Insights estimates will be worth $28.3bn (£21.6bn) by 2026, has already developed niche versions of Otter for education and use by small groups. It will use part of the investment to continue its aggressive partnership and licensing strategy.

Among others it has recently worked with Zoom to enable users of the communication software to transcribe their conversations.

The voice transcription market is expected to grow significantly in the coming decade. Otter faces many rivals including startups Verbit, Simon Says and Scribie as well as services from tech behemoths like Cisco and Microsoft.

The Otter service is available freely on a basic level of 600 minutes a month, with Otter for Teams starting at $12.50 per month.