A CAPONS TIME-OCTAVE REPRESENTATION APPLICATION IN ROOM ACOUSTICS

In time-frequency analysis, Capon's estimator has proven its efficienc y in precise applications, In a context where a time-octave representa tion is also necessary, we propose a new method combining both Capon's estimator and a time-octave representation, Our main objective is to obtain legibility in the time frequency plane using a variable frequen cy resolution with a fixed time resolution, This fixed time resolution is possible owing to the good resolution properties of Capon's estima tor compared to the Fourier transform, This choice leads to a particul ar repartition of basic cells in the time-frequency plane that seems m ore adapted to a physical interpretation in the application presented, Nevertheless, a parallel with the wavelet transform is displayed: the constructed wavelet is adapted to the signal at each octave or at eac h fraction of octave. The proposed method is presented both in continu ous and discrete formulations. Its structure is studied and a simplifi cation is proposed when precise hypotheses are verified, Simulations a nd comparisons with classical representations (spectrogram, scalogram) are discussed, The contribution of each method, essentially in the du ality of time-frequency and time-scale, are shown up in relation to th e analyzed signal. Lastly, the proposed method and classical ones are applied on real signals issued from room acoustics where the aim is th e time-frequency characterization of concert halls from impulse respon ses.