How can I remove the noise in voice file?

The attached speech.dat file has a lot of noise.

What can I do to hear exactly what it is saying?

plz let me know what it say.

[Dimitris Kalogiros]

What is the sampling frequency of your file ?

[In Sik Kim]

It is 8000Hz

[Star Strider]

Your file has a ‘.dat’ extension.

Is it a text file, or some other format?

[In Sik Kim]

It is 'dat' file

You can use just speech.dat in matlab

[Image Analyst]

Again, what format is it? It doesn't seem to be able to be read in with audioread():

Error using audioread (line 104)
The file type is not supported
Error in test2 (line 1)
[y, fs] = audioread('speech.dat')

Please attach the code you used to read it in and play it.

Answer 1

[Dimitris Kalogiros]

In the following figure, it is depicted the original signal and a filtered version of it.

If you use the sound() command;

sound(speech, 8000);

sound(speech_filtered, 8000);

There is no difference on what you are going to hear. And this is something that is expected, cause the original signal, seems to have no added noise outside its main occupied bandwidth. I tried out many cutoff frequencies at my low pass filter, but no significant improvement. The speech signal indeed is distorted, but this distortion is not an awgn.

[Dimitris Kalogiros]

...and something else: your sampling frequency must be slightly greater than 8KHz