The prediction of crowd noise is a problem faced by acoustic consultants. Although consultants are frequently re-quired to predict noise emissions from activities involving crowds of people, there are no prediction methodologies available. This paper discusses the factors influencing crowd noise with the aim of encouraging discussion about how the problem of predicting crowd noise can be overcome. Some simple analysis is presented to show how different situational factors and crowd characteristics influence the noise emitted by a crowd. Four major factors were found to influence the noise level generated by a crowd of people; an individual's voice effort, the total number of people, whether the source is synchronous or random in time and whether the crowd is directional or has a diffused orientation.