The ANSI standard for the calculation of loudness (ANSI S3.4-2007) is based on the model developed by Moore, Glasberg and co-workers, and uses the assumption that a diotic sound is twice as loud as that same sound presented monaurally. However, recent data suggest that loudness summation across ears is less than assumed in the ANSI standard. This was taken into account in the revised loudness model of Moore and Glasberg [J. Acoust. Soc. Am., 121, 1604–1612, 2007] using the concept of “binaural inhibition”, whereby the signal at one ear inhibits the internal response to a signal at the other ear. This model predicts that a diotic sound is 1.5 times as loud as that same sound presented monaurally, and it forms the basis for the proposed ISO532-2 standard. The revised model also gives reasonably accurate predictions of loudness in cases where the sounds differ across the two ears, for example, sounds recorded via a dummy head. An extension of the model to deal with time-varying sounds has been shown to give accurate predictions of loudness for a variety of technical and musical sounds. It is proposed that the revised and extended model be used as the basis for a new ANSI standard.