Hi Anita,
I was thinking about suggesting that you use an amplified LM34 temp sensor mounted in a probe that would feed a CD4046 Voltage Controlled Oscillator, but you should do your own school research and maybe a blind person couldn't use it anyway.
If I blindfolded you, then asked you to jump into water that might be boiling or freezing, but that you had a beeper with a tone that changes with temperature? Would you get in after hearing the tone? Of course not!
It might make a high pitch tone. How high is high? Or it might make a low pitch tone. How..., you know.
Unless the blind person has "perfect pitch", like very few musicians have (the ability of their brain to identify the exact frequency of a tone, something like the way that you see colours), their hearing won't have a reference to base the frequency of the tone against.
I made an alarm system for the government. One alarm beeped a low frequency slowly. Another alarm beeped a high frequency quickly. See, in addition to the frequencies being completely different, I made the beep rate also different. Can't miss it: hummmmm, hummmmm, hummmmm, or squeak, squeak, squeak, squeak, squeak. They complained that both alarms sounded the same!