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Discussion Groups | Matlab DSP | speech signal segmentation

Technical discussion about Matlab and issues related to Digital Signal Processing.

  

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speech signal segmentation - pnal...@yahoo.com - Jun 13 11:56:49 2007




Dear Friends
             I am new to DSP. I am trying to implement some speech correction algorithms but I
have some problems. Can anyone please provide a matlab m-file code or advice me on how to
segment a speech signal which has been read by the wavread function to a vector lets say X. I
would be glad for any responses.

Best regards
G.N       



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Filter function, convolution problem - Dean - Jun 14 13:40:04 2007

Dear Friends,

for  

x(n) = u(n) - u(n-10); h(n) = ((0.9)^n) u(n);

I'd like to obtain y(n)  which is equal to x(n)*h(n)

I'll normally using convolution to obtain y(n), in this case, I have to
consider when n <0; 0<=n<=9 and n>10.

Someone told me I can use filter function / command to solve it indirectly,

does anyone know how?

Regards

Dean



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Re: Filter function, convolution problem - Amit Pathania - Jun 15 9:16:57 2007

the problem states that x(n) is a causal sequence where the current value depends on the
current sample from u(n) and a delayed sample u(n-10). 
   
  so 
   
  x(n) = u(n).(1 - z^(-10))
   
  y(n) = u(n).0.9^(n).(1 - z^(-10))
   
  y(n) 
  ------ = 0.9^(n).(1 - z^(-10))
  u(n)
   
  you can arrive at the same result by using the fact that two filters h1 and h2 in serial can
be replaced by a filter having a transfer function h1.h2. 
   
  the RHS is your transfer function if you want to use the filter command
  I assume the u(n) is the generic step function with amplitude 1

Dean <w...@googlemail.com> wrote:
              Dear Friends,
  
  for  
  x(n) = u(n) - u(n-10); h(n) = ((0.9)^n) u(n);
  
  I'd like to obtain y(n)  which is equal to x(n)*h(n)
  
  I'll normally using convolution to obtain y(n), in this case, I have to consider when n
<0; 0<=n<=9 and n>10.
  
  Someone told me I can use filter function / command to solve it indirectly, 
  
  does anyone know how?
  
  Regards
  
  Dean

Amit Pathania



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Matlab MCC comliped executable speed - Amit Shaw - Jun 18 9:08:31 2007

Hi all,

I have been trying to find the reason for observations I have made
regarding MCC compiled code.

My test function looks like:

function [] = test_debug(num_sim)

num_sim = str2num(num_sim);

num_inputs = 2;

for index = 1:num_sim

    disp('Start of Simulation');

    tic;

    input_block = (rand(1,520*8) > 0.5);

    for idx = 1:length(input_block)/num_inputs

        temp = input_block((idx-1)*num_inputs+1:idx*num_inputs) *
2.^[num_inputs-1:-1:0].';

    end

    disp(sprintf('End of Simulation Count %d',index));

    toc;

end

return;

I have compiled it using :

mcc -v -x -B sgl -d ./Temp test_debug -o ../../Executable/test_debug

I ran the created executable from DOS prompt using 

test_debug 5

All the iterations gave me increasing simulation time.

Then I replaced the statement in the for loop:

 temp = input_block((idx-1)*num_inputs+1:idx*num_inputs) *
2.^[num_inputs-1:-1:0].';

with 

    x = 2.^[num_inputs-1:-1:0].';  

    temp = input_block((idx-1)*num_inputs+1:idx*num_inputs) * x;

Now it gave be uniform simulation time for each iteration in the
executable run. However While if I run this code in Matlab command
prompt both runs equally well. It is expected (a known ) issue??

Thanks and Regards,

Amit Shaw 
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