1In vertebrates, any transmission of vocal signals faces the challenge of acoustic 2 interferences such as heavy rain, wind, animal, or urban sounds. Consequently, several 3 mechanisms and strategies have evolved to optimize the signal-to-noise ratio. Examples to 4 increase detectability are the Lombard effect, an involuntary rise in call amplitude in 5 response to masking ambient noise, which is often associated with several other vocal 6 changes such as call frequency and duration, as well as the animals' capability of limiting 7 calling to periods where noise perturbation is absent. Previous studies revealed rapid vocal 8 flexibility and various audio-vocal integration mechanisms in marmoset monkeys. Using 9 acoustic perturbation triggered by vocal behavior, we investigated whether marmoset 10 monkeys are capable of exhibiting changes in call structure when perturbing noise starts 11 after call onset or whether such effects only occur if noise perturbation starts prior to call 12 onset. We show that marmoset monkeys are capable of rapidly modulating call amplitude 13 and frequency in response to such perturbing noise bursts. Vocalizations swiftly increased 14 call frequency after noise onset indicating a rapid effect of perturbing noise on vocal motor 15 pattern production. Call amplitudes were also affected. Interestingly, however, the 16 marmosets did not exhibit the Lombard effect as previously reported but decreased their call 17 intensity in response to perturbing noise. Our findings indicate that marmosets possess a 18 general avoidance strategy to call in the presences of ambient noise and suggest that these 19 animals are capable of counteracting a previously thought involuntary audio-vocal 20 mechanism, the Lombard effect, presumably via cognitive control processes. 21 Keywords22 Audio-vocal integration; Callithrix jacchus; primate communication; vocal communication; 23 vocal flexibility 24