How to add the level to a sine tone?

Hi,

I already built the noise and the sine tone, but how can i add the level (in dB SPL) to the noise and sine tone?

% Set-up parameters

fs = 22050; % This is the sampling frequency of the Titan

stim_dur = 1.; % duration of puretone in seconds

noise_dur = 1.; % 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; % Time vector

f = 10e2; % Frequency

levels = 60:5:100; % Levels dB SPL

% 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

tone = sin(2*pi*f*t);

% Setup ramp

rampSamps = floor(fs*ramp_dur); % Round toward minimum of sampling frequency and duration of ramp

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_tone = [w1 ones(1,length(tone)-length(w1))]; % Create rising/starting ramp for tone

w_off_tone = [ones(1,length(tone)-length(w2)) w2]; % Create falling/ending ramp for tone

w_on_noise = [w1 ones(1,length(noise)-length(w1))]; % Create rising/starting ramp for noise

w_off_noise = [ones(1,length(noise)-length(w2)) w2]; % Create falling/ending ramp for noise

% Ramp stimuli

noise_ramped = noise.*w_on_noise.*w_off_noise; % Add both ramps to the noise

tone_ramped = tone.*w_on_tone.*w_off_tone; % Add both ramps to the tone

Answer 1

[Jonas]

the level of a sound is usually the root mean square of the amplitude values. going on from there db SPL is calculated as 20*log10(rmsValue/(20*10^-6)). if you reverse my description you get the factor with which you have to multiply your sound.

[Jonas]

note that if you have a simple sine with amplitude A, the rms is just A/sqrt(2)

[Paul Hinze]

Thank you! I will try that