Concordo bastante com a Flávia; para mim, "ombudsman" é o que mais se aproxima de "ouvidor/ouvidoria" em português. Indo ao 'The New York Times', encontrei um artigo interessante sobre o assunto, que menciona "ombudsman agency" em um contexto semelhante ao de "ouvidoria", vejam:
Ombudsman Agency for Child Abuse Needed
The tragic beating death of 6-year-old Lisa Steinberg is still fresh in the minds of New Yorkers. Four days after her burial, there was an arrest in Brooklyn of a young woman in connection with the strangulation death of her 2-year-old daughter.
Unless we force ourselves to grapple with cruelty toward defenseless children, the lessons to be learned will soon be forgotten. One step that we at the Citizens' Committee for Children of New York have called for is establishment of an independent citywide ombudsman. An ombudsman means a totally independent government agency receiving and investigating complaints from children, parents or others, and charging abuse of power, neglect of duty, incompetence, corruption and any other condition serving to deny a child rights to a program or service established in law.
Establishing a municipal ombudsman agency would require a change in the City Charter. The effort must be made. Such a service would have the authority to disclose findings to the public and to report violations to law-enforcement officials.