[SOLVED] Frequency spectrum of a noise signal.

[sana_akhtar]

Hey

MY question is this graph right? I mean the frequency is going beyond 20kHz. Will that be audible to us or not?
Here is a FFT of a noise from a machine.
The code I used in MATLAB is :

clear all
clc;
load handel.mat
filename='memo.wav';
[y,Fs]=wavread(filename);
t=0:1/Fs:(length(y)-1)/Fs; 
figure (1),
plot(t,y)
title('Orginal Signal y(t)')
xlabel('Time (sec.)')
ylabel('Signal (y)')

n=length(y)-1;
f=-Fs/2:Fs/n:Fs/2;
sigFFT= fft(y);
figure(2),
plot(f,abs(sigFFT))

title('Single-Sided Amplitude Spectrum of y(t)')
xlabel('Frequency (Hz)')
ylabel('|Y(f)|')

 

[BradtheRad]

I mean the frequency is going beyond 20kHz. Will that be audible to us or not?

Although it is above the range of normal human hearing, intense ultrasonic sounds are able to cause painful sensations, and fatigue.

I saw a study described in a hi-fi magazine, in which listeners reported they could 'sense' whether there were ultrasonic frequencies present in music being played for them.

 

[Audioguru]

Some people can hear higher than 20kHz and some people cannot hear anything above 3kHz because we are all different.
When I was in my late teens and early 20ies I heard ultrasonic burglar motion detectors clearly and painfully.

The noise from the printer in your other thread can easily destroy the high frequency hearing of anybody nearby.

When you measure the noise from the printer then you must use a microphone that does not become overloaded and has a frequency response high enough.

 

[chuckey]

Whilst at college I attended an extra curriculem lecture by one of the leading audiophiles of the 1960s. The demonstration that impressed me the most was when he played various tones through his system, a sine wave, a square wave and a triangular wave at different frequencies. Nothing strange about that?, well when the fundamental got up to 16 KHZ, you (I) could hear the difference, this means that with a triangular wave, it was the 32 KHZ component and for the square wave it was the 48 KHZ component. These components should be beyond our hearing range, but they have an effect. Not a big one, but an effect.
It could be said that the slightly super sonic sound is actually very dangerous, because the sound pressure could be physically damaging ones hearing, but its audible effect is minimal.
Frank