Talking CCTV cameras, due to be installed in 20 areas across England, may be a "bridge too far", the UK's Information Commissioner has said.
Mr Thomas has called for vigorous debate on the issue
Richard Thomas also raised concerns about the possibility that tiny cameras could be hidden from view and listening devices installed alongside cameras.
He told MPs the effectiveness of CCTV was not proven, although he accepted they were popular with the public.
The Home Affairs Committee inquiring into the "Surveillance Society".
The committee pointed out that CCTV was very popular with the public, which often called for its installation.
But Mr Thomas said Home Office research had indicated there were "still doubts as to the efficacy" of CCTV, both in terms of preventing and detecting crime.
And his deputy, David Smith told the committee that sometimes more vigorous assessment was needed about whether the cameras were a "proportionate" response to the problems in an area.
Both argued people should know where CCTV cameras were - possibly by way of a website map - and expressed alarm about the potential for tiny cameras to be "buried" in lamposts.
And Mr Thomas added: "We would be hostile to the suggestion of any sort of microphones in relation to cameras... we think that would be unacceptable."
Regarding the loudspeakers on lampposts - which have been trailed in Middlesbrough and are being rolled out across 20 areas - he said: "That may be a bridge too far ... we are certainly not enthusiastic about that kind of approach."
They were also concerned about the potential use of automatic facial recognition technology - used by police to look for known criminals - in shops.
'Short on examples'
Mr Smith, who said he did not like trying on clothes in shops and preferred to take them home and return them if necessary, said: "I would worry about being labelled a shoplifter."
Committee chairman John Denham said Mr Thomas appeared to be short on examples of people whose lives had been adversely affected by CCTV and data sharing.
But they cited a case in Essex where CCTV images of a man who had been trying to commit suicide were later used on television to illustrate the benefits of CCTV in tackling crime.
The Information Commissioner is working on an updated code of practice for CCTV cameras, as well as one on sharing information between public sector organisations.
He said it was important there was not a "free-for-all" by police and other agencies on accessing people's information.
He has warned that a "climate of fear" may be created unless excessive surveillance is curbed, and said it was wrong that organisations could not be inspected without consent.
He wants government departments to carry out privacy impact assessments on all proposed schemes - to show how they could minimise threats to privacy.
He said as well as the risks of mistakes, there could also be "unnecessary intrusion" into people's lives.
The Information Commissioner's Office was set up to uphold data protection laws and promote public access to official information.
There are up to 4.2m CCTV cameras in Britain - about one for every 14 people - and the UK also holds 3.6 million DNA samples, which is the world's biggest database.