Patent ID: 8544327

Claim:
An acoustic impedance sensor designed to measure the input acoustic impedance (Z) of a waveguide (GU), the sensor comprising a source coupled to the waveguide (GU) by means of an open cavity (CAV 2 ), referred to as the front cavity, delimited by the source and emerging on the said waveguide (GU), and a cavity (CAV 1 ), referred to as the rear cavity, closed by said source, the acoustic pressure in each cavity being measured by a microphone, said sensor being configured such that said source is a piezoelectric pellet (PA) mounted between the rear cavity (CAV 1 ) that is in the form of a straight cylinder and the front cavity (CAV 2 ) that is in the form of a straight cylinder, the height (L 2 ) of the front cavity and the height (L 1 ) of the rear cavity being respectively less than one quarter and one half of the wavelength of the excitation emitted by said piezoelectric pellet (PA) and the diameters (d 1 and d 2 ) of the two cavities (CAV 1 and CAV 2 ) being less than half of said wavelength.