audio recording

I bought a (used) cassette deck yesterday, worked fine in store but I didn't test out the recording cause I didn't have blank tapes with me, or recording gear. I tested out the recording this morning, and there is a very loud hum noise, almost like electrical hum, but it sounds similar to when...

Hi everyone. Can anyone please tell me how to record the audio playing on a computer WITHOUT recording the audio in the surrounding environment? I want to record the audio of a video on my computer, but I don't want to record background noises from outside of my computer. I haven't been able...

Hi all, it is possible to record or capture frecuencies above the 19Kh or lower the 20hz with a cell phone, like an iphone? I'd like to make an app to capture frecuencies that the human ear can't. Is that possible? Thanks.