Measurements of the transfer function of headphones and earphones are made on dummy-heads or on ear simulators. This paper introduces measurement problems of newly designed in-ear phones, often called as micro-driver equipment. These earphones have smaller transducer diameter and are equipped with rubber or spongy material to fit in the ear canal. This coupling may create an increased sound isolation, less sound pressure and a better low frequency transmission to the eardrum. The paper presents subjective evaluation of listeners who evaluated five different kinds of in-ear phones as well as transfer function measurements using a dummy-head. Measurement problems are highlighted pointing on new aspects of a revised dummy-head standard. Copyright © (2010) by the International Congress on Acoustics.