How do I amplify my sound using soundsc?

I want to amplify the sound I produced using soundsc by raising the sound by a steady increase of dB. I am trying to make a hearing test so I need to increase the dB if the user cannot hear. Code:

fs = 8000; %sampling rate
dur = 3; 
tt = 0 : 1/fs : dur; %time duration
f=1000; %frequency
vol= db2mag(1);
y=vol*sin(2*pi*f*tt);
soundsc( y, fs );

Where do I apply the dB? When I multiply it to the signal I do not notice a change. Say i increase it from 1 dB to 10, I still do not hear the difference. Another issue, at certain frequencies my sound sounds extremely distorted such as at 20kHz and 30kHz. Why is this? And at certain higher frequencies my sound sounds like it is a lower frequency. For example, at 29kHz it sounds higher than 31kHz. I am fairly new to Matlab so help would be appreciated.

Answer 1

[Jan]

soundsc scale the sound already until the amplitude reachs 1.0 . Try sound instead or audioplayer.

If you have a sampling frequency fs of 8kHz, you cannot create a signal with 29 or 31 kHz. Only frequencies upto half of the sampling rate can be represented. Otherwise the signal has several periods between two time steps. You can see this, by plotting a signal with 7999Hz and 8001Hz. Look in the net for "Nyquist"

[Sergio Campos]

Oh I see that makes sense. I used sound instead and it came out fine, I totally forgot about that the sampling rate has to be double the frequency used. Thank you so much!

[Jan]

You are welcome. You've asked a perfect question: Exhaustive descriptionof inputs, outputs and problem, meaningful title and tags, code formatted and a short friendly sentence. Obviously you've spent time to provide all details required for a solution.

This is my

 Question Of The Week! :-)

Seriously, you encourage others to invest their time in assiting you.

[keshav poojari]

Sir.. Can i amplify Prerecorded audio in R2013a release?

[Walter Roberson]

Can i amplify Prerecorded audio in R2013a release

Yes.

amp = 4/3;    %turn it up loudER
filename_in = 'never_going.wav';
filename_out = 'give_you_up.wav';
[data, fs] = audioread(filename_in);
new_data = data*amp;
new_data = max( min(new_data, 1), -1 );   %clip when it gets too loud
audiowrite(filename_out, new_data, fs);