1. A speaker recognition method, comprising steps of: (a) acquiring a speech signal of a speaker who has a vocal tract and thereby providing a speaker's speech signal; (b) deriving samples of said speaker's speech signal (c) determining averages of cross-sectional dimensions of cylinder portions of a lossless tube model of the speaker's vocal tract using the samples derived from the speaker's speech signal, each said cross-sectional dimension including a radius, a diameter or a cross-sectional area of a respective cylinder portion of the lossless tube model, (d) comparing said determined averages of said cross-sectional dimensions with the corresponding averages of cross-sectional dimensions of corresponding cylinder portions of a stored vocal tract model of at least one known speaker.