Traditionally the description of the acoustical behavior of a bore has been done in the frequency domain through the acoustical impedance or the reflection coefficient. Whenever the time‐domain response of it (impulse response, reflection function) has been needed, it has usually been obtained through the Fourier transform (FT) of the corresponding frequency‐domain function. However, there are a number of cases in which this approach is unsuitable because the FT leads to noncausal functions which cannot be understood physically as impulse responses or reflection functions. In such cases the time‐domain calculation is unavoidable. This calculation leads to exponentially growing functions which obviously do not accept an FT. This article presents the time‐domain calculation of the main basic functions (reflection and transmission functions associated with a single discontinuity, impulse responses of anechoic bores) which are needed to obtain the input reflection function and the impulse responses of a bore....