Impulse response measurements that are performed outdoors are highly susceptible to the uncertainties caused by the non-perfect measurement setup, the presence of background noise, and fluctuations in media such as wind and temperature drift. This work concentrates on two scenarios: the measurement of reflection coefficients of noise barriers and the influence of temperature variances in machinery cavities. Regarding the sound barrier measurement outdoors, a linear four-microphone array can be used to separate direct sound and reflected sound if the sound barrier does not include complicated scattering structures. With regard to the impulse response of an air-borne sound measurement for a machine monitoring system, a time-warping model for inter-period and intra-period temperature variances is investigated.