The Haskins site includes several example analysis files that you can download. These files contain, in a compact form, all the data you need to resynthesize the sinewave speech. The Matlab routines below do this for you.

- README - usage details
- synthtrax.m - the main synthesis routine
- slinterp.m - subsidiary linear interpolation routine
- readswi.m - function to read the SWI-format data files into Matlab
- s1pars.swi, s6pars.swi - example paramters files from the Haskins site.

I was developing some examples of LPC analysis for my speech and audio class, and to my surprise, crude translation of LPC pole positions does a pretty good job of extracting sinewave speech parameters. Thus, I am pleased to offer the following routines:

- Main routine: [F,M] = swsmodel(D,R,H) returns four sinusoids, with frequencies defined by rows of F and magnitudes defined by rows of M, tracking the formants in the speech sample D (of sampling rate R). Each column of F and M corresponds to H samples (so the analysis frame rate is R/H). Note: the sound is resampled to 8 kHz within the routine to focus the LPC on the main formant region, below 4 kHz.
- Support routine:
- [A,G,E] = lpcfit(D,P,H,W,O) fits P-th order LPC (all-pole, autoregressive) models to sound waveform D, using W-point windows advanced by H samples. Rows of A contain all-pole filter coefficiets [1 a1 a2 .. aP], with corresponding elements of G giving the frame gain (residual RMS). E is the actual excitation residual. Specifying OV as zero prevents overlap-add of the residual, for perfect reconstruction but a less useful E.
- Support routine: [F,M] = lpca2frq(A) factorizes the LPC polynomial defined in each row of A (as from lpcfit.m) and returns the sorted positive frequencies (up to P/2 of them) in columns of F, each with a corresponding approximate magnitude in M.
- Bonus routine: D = lpcsynth(A,G,E,H,OV) resynthesizes from LPC parameters returned by lpcfit, or using noise excitation if E is omitted.

An example use is shown below:

>> [d,r] = wavread('mpgr1_sx419.wav'); >> [F,M] = swsmodel(d,r); >> plot(F'); % show all the frequencies >> dr = synthtrax(F,M,r); >> % Listen to it >> sound(dr,r) >> % Compare to noise-excited reconstruction of LPC analysis >> [a,g] = lpcfit(d); >> dl = lpcsynth(a,g); >> sound(dl,a); >> % The LPC reconstruction is based on more or less the same information >> % as the sinewave replica, but it sounds less 'weird' >> % Compare the spectrograms >> subplot(311) >> specgram(d,256,r); >> title('Original'); >> subplot(312) >> specgram(dr,256,r); >> title('Sine wave replica'); >> subplot(313) >> specgram(dl,256,r); >> title('Noise-excited LPC reconstruction');

If you wish to reference this code in your publications, you can use the following citation:

D. P. W. Ellis (2004) "Sinewave Speech Analysis/Synthesis in Matlab", Web resource, available: http://www.ee.columbia.edu/ln/labrosa/matlab/sws/ .

Last updated: $Date: 2013/12/04 13:19:35 $

Dan Ellis <dpwe@ee.columbia.edu>