sound of a sequence of 0 and 1

Hello everybody,

I have this pulse_sequence and I'd like to make it sound with the sound function and cosinus I have below. The problem is that I want to make the ones as sound but the zeros as silence, and I don't know how to do it because the length of the pulse_seq is of 115 but the length of the cosine is of 48481. Perhaps using repmat would be feasible but I don't know how.

Thank you very much!

pulse_seq = "01010101000111011101110001011101010001011100000001011101110111011100010101110111011100010101011101110"

dot_duration = 0.06;
tone_frequency = 750;
sampling_frequency = 8000;
F=tone_frequency/sampling_frequency;
dot_samples=strlength(pulse_seq)*dot_duration
t_seq=0:1/sampling_frequency:dot_samples

sound(cos(2*pi*tone_frequency*t_seq),sampling_frequency)

[Rik]

If you have a sound you want for every 1, you could use your pulse array as an index into a sound dictionary. The easiest way would be to use a cell array to store your two sounds (even if one of them is silence of a given duration).

[Mireia Boneta Camí]

Hi Rik I don't understand what you mean by using a cell array to store my two sounds. What sounds? I'd like to make the pulse_seq sound as the cosine below, but only the ones (the 0s as silence)

[Rik]

I though you essentially wanted this:

pulse_seq = '01010101000111011101110001011101010001011100000001011101110111011100010101110111011100010101011101110';
for n=1:numel(pulse_seq)
    if strcmp(pulse_seq,'0')
        sound(zeros(size(t_seq)),sampling_frequency)
    else
        sound(cos(2*pi*tone_frequency*t_seq),sampling_frequency)
    end
end

Answer 1

[Freewing]

First of all, you'd want your t_seq to be of length 48480 which is strlength(pulse_seq)*dot_duration*sampling_frequency:

pulse_samples = dot_duration * sampling_frequency;
num_samples = strlength(pulse_seq) * pulse_samples;
t_seq = (0:num_samples-1) / sampling_frequency;

Now you need a pattern of 0s and 1s of length num_samples, you can make it in a loop like that:

sig = ones(1, pulse_samples);
pattern = zeros(1, num_samples);
pulse_char = char(pulse_seq); % convert pulse_seq to char array
for j = 1:length(pulse_char),
    if pulse_char(j) == '1', % copy sig only when there's '1' in char array
        ind = 1 + (j-1)*pulse_samples : j*pulse_samples; % index of pattern corresponding to j
        pattern(ind) = sig;
    end
end

Apply pattern to your cosine wave and play sound:

s = cos(2*pi*tone_frequency*t_seq) .* pattern;
sound(s, sampling_frequency);

Now if you want it to sound smoother (no clicks), you'd like to smooth out your sig pulse:

sig = ones(1, pulse_samples);
smooth_samples = 0.005 * sampling_frequency;
t = (0:smooth_samples-1) / (smooth_samples-1);
sig(1:smooth_samples) = sig(1:smooth_samples) .* smoothfunc(t);
sig(end-smooth_samples+1:end) = sig(end-smooth_samples+1:end) .* smoothfunc(1-t);

Use this function which goes from 0 to 1 smoothly as its argument goes from 0 to 1:

function s = smoothfunc(t)
    s = -2*t.^3 + 3*t.^2;
end