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When I try to do a Fourier analysis of a WAV file with a sample rate of 22050 I get an error "Cannot take positions". What am doing wrong?

In[5]:= Import[path,"Options"]
Out[5]= {AudioChannels->1,AudioEncoding->Integer16,SampleRate->22050}

In[13]:= ListLinePlot[Abs[Fourier[signal2[[0;;22050]]]]]
During evaluation of In[13]:= Part::take: Cannot take positions 0 through 22050 in {-0.139099,-0.143005,-0.147125,-0.149109,-0.14563,-0.136719,-0.12442,-0.102112,-0.0857239,-0.0933228,-0.115112,-0.132629,-0.14621,-0.165161,-0.18399,-0.194122,-0.194702,-0.184052,<<15>>,0.144867,0.124451,0.100403,0.0848694,0.0855713,0.100586,0.11911,0.128052,0.123932,0.110077,0.0941772,0.0918274,0.107971,0.134216,0.157959,0.176849,0.187927,<<905296>>}. >>
During evaluation of In[13]:= Fourier::fftl: Argument RowBox[{\({\(-0.13909912109375`\), \(-0.14300537109375`\), \(-0.147125244140625`\), \(-0.14910888671875`\), \(-0.1456298828125`\), \(-0.13671875`\), \(-0.124420166015625`\), \(-0.10211181640625`\), \(-0.085723876953125`\), \(-0.09332275390625`\), \(-0.1151123046875`\), \(-0.13262939453125`\), \(-0.146209716796875`\), \(-0.1651611328125`\), \(-0.183990478515625`\), \(-0.194122314453125`\), \(-0.1947021484375`\), \(-0.184051513671875`\), \(<< 15 >>\), 0.144866943359375`, 0.12445068359375`, 0.10040283203125`, 0.084869384765625`, 0.0855712890625`, 0.1005859375`, 0.119110107421875`, 0.1280517578125`, 0.123931884765625`, 0.110076904296875`, 0.09417724609375`, 0.091827392578125`, 0.10797119140625`, 0.13421630859375`, 0.157958984375`, 0.176849365234375`, 0.18792724609375`, \(<< 905296 >>\)}\), "[[", RowBox[{"0", ";;", RowBox[{"", \(<< 5 >>\), ""}]}], "]]"}] is not a non-empty list or rectangular array of numeric quantities. >>
During evaluation of In[13]:= ListLinePlot::lpn: Abs[Fourier[{-0.139099,-0.143005,-0.147125,-0.149109,-0.14563,-0.136719,-0.12442,-0.102112,-0.0857239,-0.0933228,-0.115112,-0.132629,-0.14621,-0.165161,-0.18399,-0.194122,-0.194702,-0.184052,<<16>>,0.124451,0.100403,0.0848694,0.0855713,0.100586,0.11911,0.128052,0.123932,0.110077,0.0941772,0.0918274,0.107971,0.134216,0.157959,0.176849,0.187927,<<905296>>}[[0;;22050]]]] is not a list of numbers or pairs of numbers. >>
Out[13]= A very large output was generated. Here is a sample of it:
ListLinePlot[Abs[Fourier[{-0.139099,-0.143005,-0.147125,-0.149109,-0.14563,-0.136719,-0.12442,-0.102112,-0.0857239,-0.0933228,-0.115112,-0.132629,-0.14621,-0.165161,-0.18399,-0.194122,-0.194702,<<905313>>,0.0675659,0.0622253,0.0541382,0.0477905,0.0399475,0.0280457,0.015564,0.00323486,-0.00512695,-0.00515747,-0.00265503,-0.00686646,-0.0162048,-0.0269775,-0.0352173,-0.0334473}[[0;;22050]]]]]
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  • $\begingroup$ For one thing, MM is 1 indexed... $\endgroup$
    – ciao
    Commented Jan 16, 2014 at 3:49
  • $\begingroup$ It might be an indexing error: vectors start with 1 and not 0, so you might try signal2[[all]] or signal2[[1;;Length[signal2]]]. $\endgroup$
    – bill s
    Commented Jan 16, 2014 at 4:16

1 Answer 1

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3
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You are trying to take 22051 elements from an list that's only 22050 elements long. To demonstrate the problem, this gives the same error:

x = {1, 2, 3}
Take[x, 4]
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