M-FSK - demodulation and recovering bits

Hello. I have the 16-FSK modulated signal.

[y,fs] = audioread('signal.wav');

And then I have to recover bits that are coded by different frequency values. I was trying demodulation:

fc=6; %default
M=16;
fskdemod=comm.FSKDemodulator(M, fc, 'SamplesPerSymbol', 4, 'BitOutput', true); 
z=fskdemod(y);

But I don't think the output is correct. Can you give me any clue?

And there is fragment: