Of the 317 audit committee members polled, about 70 percent rated their committee as "very effective." In addition, when it came to helping ensure the external auditor's independence from management and accountability to the audit committee, nearly 85 percent rated themselves "very effective."

But there remains room for improvement. For example, nearly one in three said they were not fully satisfied with the committee's oversight of management's accounting judgments and estimates. Eighty percent of those surveyed by KPMG's ACI said they were not fully satisfied with the board's or audit committee's oversight of risk management or the processes that management uses to identify and manage the company's risks. And nearly 40 percent said the approach used to establish the committee's agenda/work plan could be improved.

"Audit committees are developing a greater appreciation for the tentative and 'fragile' nature of critical accounting judgments and estimates and their effect on the company's financial statements," said Kenneth Daly, executive director of KPMG's Audit Committee Institute (ACI), which conducted the survey with the National Association of Corporate Directors (NACD). He noted that complex accounting standards and pressures to meet earnings estimates have contributed to the risk of errors.

Oversight of risk management also is a major area of concern. Many audit committee members polled were not fully satisfied with management's process to identify and address risks facing the company, or with the committee's oversight of that process. About one in three said there was no clearly defined process for assigning risk oversight responsibilities among the board and its committees, and more than half believe the audit committee should not have primary responsibility for oversight of the company's risk-management program.

"There continues to be a general lack of understanding and clarity about roles and responsibilities in this evolving area of oversight," said Daly.

Regarding specific areas of risk, many audit committee members identified room for improvement in their oversight of internal controls (36 percent), financial reporting implications of taxes (59 percent), fraud risk (61 percent), and information security (78 percent). In addition, most (84 percent) expressed concern that the lengthy checklist of the audit committee's more routine compliance activities may "detract from substantial discussion" of company issues and negatively impact the committee's overall effectiveness.

Although many audit committee members said they generally are satisfied with their interaction and support from management, auditors, and others, a considerable number cite room for improvement: Roughly one in three respondents said support from the CEO, external audit partner, in-house and external legal counsel, corporate secretary, and the full board could be better.

"What we're seeing in these survey results is a combination of healthy skepticism, with audit committees asking more probing questions about critical areas of oversight, and a real need to continue strengthening the financial reporting process overall," said Daly.