MATLAB: Rise/fall time

rise timesine wave

Hi, can anyone help me to generate 2 sounds of 500 and 1000 Hz with 25 ms duration with ISI of 30 ms and rise/fall time of 10 ms with Fs of 44100 and I want to 500 Hz be 10 dB less than 1000 Hz

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%set-up parameters
fs=44100; %CD quality - also conveniently divisible by 30 and 25
stim_dur=.025; %duration in seconds
ISI_dur=.030; %ISI duration in seconds
ramp_dur=.010; %ramp duration in seconds
t=0:1/fs:stim_dur-1/fs;
f1=500;
f2=1000;
%create signals
xt1=sin(2*pi*f1*t);
xt2=sin(2*pi*f2*t);
%setup ramp
rampSamps = floor(fs*ramp_dur);
window=hanning(2*rampSamps)'; %hanning window is cosine^2 this will change depending on the kind of ramp you want
w1=window(1:ceil((length(window))/2)); %use the first half of hanning function for onramp
w2=window(ceil((length(window))/2)+1:end); %use second half of hanning function of off ramp
w1 = [w1 ones(1,length(xt1)-length(w1))];
w2 = [ones(1,length(xt1)-length(w2)) w2];
%ramp stimuli
xt1_ramped = xt1.*w1.*w2; 
xt2_ramped = xt2.*w1.*w2; 
%generate ISI
ISI=zeros(ISI_dur*fs,1);
%final stimulus
out=[xt1_ramped';ISI;xt2_ramped'];
plot(out)

Related Solutions

MATLAB: Simultaneous noise and pure tone

How your sounds currently are set up, they are concatenated to be added one onto the other. If you change your concatenation to an addition so they overlap, then that should fix your problem. You'll also need to pad your signal so that it is centered in the noise

pad=zeros(1,(length(noise_ramped_10dB)-length(xt_ramped))/2); %figure out the number of zeros to center the signal
padded_xt=[pad,xt_ramped,pad]; %pad the signal
combined=padded_xt+noise_ramped_10dB; %add the signals together
plot(combined)

MATLAB: Generating pure tone and noise

See here for an excellent solution to generating your noise from one of your previous questions:

Generate noise

You can use the code from the previous answer I gave you to add a rise-fall time for 10 ms and the other stimulus.

the 10 dB SNR should also be the same. Example below.

%set-up parameters
fs=44100; %CD quality - also conveniently divisible by 30 and 25
stim_dur=.025; %duration of puretone in seconds
noise_dur=.200; %duration of noise in seconds
ISI_dur=.020; %ISI duration in seconds
ramp_dur=.010; %ramp duration in seconds
t=0:1/fs:stim_dur-1/fs;
f=1000;
%create noise
nsamples = floor(noise_dur*fs);
noise_all_Hz   = randn(nsamples,1);
noise = bandpass(noise_all_Hz,[950 1050],fs);
noise=noise';
%create 1000 Hz tone
xt=sin(2*pi*f*t);
%setup ramp
rampSamps = floor(fs*ramp_dur);
window=hanning(2*rampSamps)'; %hanning window is cosine^2 this will change depending on the kind of ramp you want
w1=window(1:ceil((length(window))/2)); %use the first half of hanning function for onramp
w2=window(ceil((length(window))/2)+1:end); %use second half of hanning function of off ramp
w_on_xt = [w1 ones(1,length(xt)-length(w1))];
w_off_xt = [ones(1,length(xt)-length(w2)) w2];
w_on_noise = [w1 ones(1,length(noise)-length(w1))];
w_off_noise = [ones(1,length(noise)-length(w2)) w2];
%ramp stimuli
noise_ramped = noise.*w_on_noise.*w_off_noise; 
xt_ramped = xt.*w_on_xt.*w_off_xt; 
% scale
rms_xt_ramped=rms(xt_ramped); %check the average intensity of the ramped 500 Hz signal
amp_10dB=10^(-10/20)*rms_xt_ramped; %find the new amplitude that is 10 dB lower
%normalize the xt2_ramped stimulus and then scale to -10 dB
noise_ramped_norm=noise_ramped./rms(noise_ramped);
noise_ramped_10dB=noise_ramped_norm.*amp_10dB;
%check
rms_noise_ramped=rms(noise_ramped_10dB);
20*log10(rms_xt_ramped/rms_noise_ramped)
%generate ISI
ISI=zeros(ISI_dur*fs,1);
%final stimulus
out=[noise_ramped_10dB';ISI;xt_ramped'];
plot(out)
sound(out,fs)

Best Answer

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MATLAB: Simultaneous noise and pure tone

MATLAB: Generating pure tone and noise

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