The study of reading aloud contributes to the erroneous assumption that speech is regular and thus measurable. Spontaneous speech calls for a rhythmic organization, and as such, an analyses based on perception. Reading aloud calls for a metric organization and quantificational analysis. This metric/rhythmic opposition can be associated with the existence/non-existence of units in speech production and perception. The choice of corpus is crucial then, for the rhythmic theory depends on it.