The Sony MDR-NC11 Noise Canceling Headphones have all the strengths and weaknesses inherent in the ear-bud design. Well-designed ear-buds can provide superior bass response and isolation from external noise than open-air headphones, but some people find them difficult to wear. Sony increases the odds of a good fit by providing three sizes of rubber earpieces, as well as a host of accessories including an inline volume control. Our test unit produced solid bass, transparent midrange, and a slightly exaggerated high end, and it had the most effective noise cancellation we've heard in consumer headphones.