How to change SNR value of noise signal?

I have clean speech samples and environmental noise samples. I need to add noise to clean speech at different SNR levels. How can I change SNR value of noise samples?

Answer 1

[Greg Heath]

Multiply the noise samples by a constant before adding to the signal.

Thank you for formally accepting my answer

Greg

Answer 2

[Siddhesh Karbhari]

I want SNR value of noise sample as -10,-5,0,5,10. What should I do?

[Image Analyst]

Since you said "I need to add noise" you would do this:

yNoisy = y + noiseSignal;

Answer 3

[Siddhesh Karbhari]

Can anyone please tell me how to change SNR value of QUT-Noise samples?

[Image Analyst]

Greg did. Did you overlook his answer? He said to multiply your noise signal by some amplification factor before adding:

yNoisy = yNoise + amplitude * noiseSignal;

By the way, a signal will have an SNR - a "QUT-Noise" signal will not. Noise alone has no SNR, or it's basically zero, since there is all noise (only noise by definition) and no signal. So you should not use terminology like "SNR of the noise".