A French city is planning an experiment that involves placing surveillance microphones on the streets

A French article, I translated it with DeepL:

Microphones in the streets: the experiment postponed to Saint-Étienne
May 8, 2019 A 09:09 by Justin Boche
The city of Saint-Étienne has announced that the experiment to install about 50 sound sensors to identify abnormal noise, which was scheduled to take place on Thursday, May 9, will be postponed until the CNIL’s final opinion is received. This answer is also of interest to the city of Lyon, which has expressed its interest in this system.

Last March, Lyon Capitale reported that the city of Saint-Étienne was going to experiment with the installation of about fifty microphones (sound sensors) to identify abnormal noise in order to allow emergency services to intervene more quickly. This issue has raised many fears among residents, particularly in the Beaubrun-Tarentaize district. The city is now awaiting the final opinion of the CNIL (Commission Nationale Informatique et Libertés) on this type of instrument set up by the company Serenicity, created in Saint-Étienne and co-founded by the Saint-Étienne company Verney-Caron. The stéphanoise municipality ensures that these “sound sensors” do not “transfer or record a sound”. “They make it possible to detect abnormal noise in public spaces (broken windows, squeaking tires, screams), alerting the video surveillance agent who can then direct the camera accordingly, towards the source of the noise for a more efficient and rapid analysis of the situation,” she describes.

The CNIL also asked the municipality of Saint-Étienne to send it additional information to formulate its conclusions. As a result, the implementation of the scheme scheduled for 9 May will not take place on time. “Under these conditions, the City of Saint-Étienne will proceed with the temporary installation of sensors when the CNIL has given its final opinion”, wrote the City of Saint-Étienne. A public meeting will also be held to inform residents at an unknown date.
And Lyon?

During the presentation last January of the partnership between Lyon and Barcelona as part of the Secur’Cities project, Régine Poulet, the director of security and prevention services at the city of Lyon, assured that sound signature recognition software was being studied in Lyon to “identify abnormal noises”, such as a scream or an explosion, in order to point the cameras at the source of this sound. Since then, no such measures have been announced by the Executive. The final opinion of the CNIL could provide them with answers.

Translated with www.DeepL.com/Translator