Is there a way to convert the IR signals from remote controls (for TV's, DVD players, etc.) into audible sound signals? There is a good circuit online, but it uses the CA3237E which is obsolete, so now I'm stuck. How would you demodulate the IR signals? With a 4046?
I am not sure why you would like to do that but a simple IR receiving diode and a preamp connected to an audio amplifier would do the trick. Be aware that most IR transmitters for TV controls transmit the codes using a subcarrier frequency that will be above the human audible range.
Take a look at a device like the TSOP-38238 (link) as an example.
You certainly can't hear the 38 - 40 kHz tone bursts. But you certainly can hear their envelope, which is about ten to twenty times lower in frequency. So if you simply connect an IR-remote receiver up to an audio amp, you'll hear a very short burst of some kind of tone. What exactly you hear depends on how bits are encrypted, and how many bits are sent.
Your ear won't be able to decode the bits, but you'll hear something.