# Resampling signal in MATLAB

I read a wav file in MATLAB and it has a sampling rate of 16kHz. I want to pass it through a filter I designed which has a sampling rate of 44.1 kHz. So, I thought I would use resx=resample(x,44100,16000) first in order to make them have the same sampling rate. I can see that I will have more samples in time now, but what is the expected change of the fft of my signal? I thought that the fft of the resampled signal would be the fft of the initial signal (0-8kHz) stretched to (0-22.05kHz) but according to the MATLAB plots it is not. Is it logical?

To add to Famous Blue Raincoat's comment: the process of upsampling a signal aims to increase its sampling rate without affecting the signal otherwise. In your example, outputting x or resx through your sound card should produce exactly the same sound. Upsampling is useful when you need to match sampling frequencies between different systems without affecting the signals otherwise.