Males of the grasshopper Chorthippus dorsatus produce songphrases which contain two differently structured elements — pulsed syllables in the first part (A) and ongoing noise in the second part (B). Females of Ch. dorsatus answer to artificial song models only if both elements A and B are present. Females strongly prefer song models in which the order of elements is A preceding B. Females discriminate between the two elements mainly by the existence of gaps within A-syllables. Pulses of 5–8 ms separated by gaps of 8–15 ms make most effective A-syllables, while syllable duration and syllable intervals are less critical parameters. Females respond to models which contain more than 3 A-syllables with high probability. Female model preferences lie well in the range of parameter values produced by singing males, except for B-parts which must be longer than those of any natural song to be most effective. In ancestors of Ch. dorsatus the two elements of the songs might have been directed towards females (part A) and males (part B).