A voice for Cologne – Aristech provides the AI voice for the KVB

Colognes public transport operator (KVB) has a new voice – and it comes from Aristech. Together, we have developed and integrated the text-to-speech (TTS) solution that will be heard throughout Cologne in future: on trams, underground trains, buses and at stops. The result is a consistent, recognisable voice that combines information with a sense of identity.

A voice that sounds like Cologne

Until now, the KVB has used different voice systems across its various modes of transport and networks. Now everything is being brought together: “One Voice for Cologne” ensures consistency and reliability – both in everyday situations and in exceptional circumstances.

Following a public tender, Aristech was awarded the contract and has been providing technical and technological support for the project since February 2024. Our language experts evaluated anonymised recordings of female speakers and ultimately recommended Sandra Rosenthal (Radio Köln) to the KVB. Her vocal profile combines Rhineland prosody with clear intelligibility – perfect for public spaces and for passengers from all over the world.

From voice to technology

The professional recording of the female voice was carried out in our Aristech studio. The basic TTS recordings, which were used to train the AI voice, were also made there.

The result: a natural-sounding synthetic voice that can generate new announcements in real time, based on up-to-date timetable data or manual inputs from the control centre.

Deep integration into KVB’s IT infrastructure

Our TTS solution has been seamlessly integrated into the KVB’s complex system architecture: via the computerised traffic control system (ITCS) and a central data hub, the generated announcements are distributed to various output channels – such as digital passenger information displays (DFI) at stops and multifunctional displays (MFA) in the vehicles.

This results in:

• Consistent announcements across all channels
• Real-time synthesis in the event of disruptions, construction work and special circumstances
• Bilingual announcements at key stops

High reliability even with short-notice ad hoc information

This infrastructure creates a networked information chain that optimally complements acoustic and visual systems in line with the dual-sensory principle. The new voice infrastructure improves the quality of information in everyday operations and ensures clear communication during disruptions. Disruption and diversion information from the control centre is distributed system-wide in real time – passengers benefit from clear, comprehensible and consistent announcements that build trust.

“Consistency, bilingual availability and rapid responsiveness improve the flow of information both in everyday situations and during disruptions,” says Carolin Edler-Mende, co-founder and managing director of Aristech GmbH.

The Future of the Corporate Voice

With its new TTS infrastructure, KVB is laying the foundations for a corporate voice strategy that extends beyond local transport. In future, this consistent voice can also be used for service hotlines, online channels and social media platforms – ensuring recognisable, trustworthy communication across all touchpoints.

What began as a technical project has ultimately become a part of Cologne’s identity. Thanks to modern AI voice technology, the city now sounds just as it is: open, friendly, easy to understand – and unmistakably Cologne.

Project facts at a glance

• Project start: February 2024
• Partner: Kölner Verkehrsbetriebe AG (KVB)
• Technology & integration: Aristech GmbH
• Voice: Sandra Rosenthal (Radio Köln)Scope: TTS solution, system integration (ITCS, data hub), studio recordings, voice evaluation and project support