Time-harmonic convention of exp(-iωt) can be preferable to exp(+iωt) (L)

Since (±i)² = -1, there are two time-harmonic conventions, namely, exp(+iωt) and exp(-iωt) with ω and t for angular frequency and time, respectively. Both conventions are mathematically valid. However, a question may still be asked whether a specific acoustic problem can favor one or the other convention. This letter reports one such example in which the use of exp(-iωt) can be preferable when the principal value of the square root of a complex number is considered as an argument of the Hankel functions in the context of 2.5-dimensional problems.