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Recording and listening to audio through a real time filter

  1. Dec 28, 2013 #1
    Could it be possible with the current technology to record the surrounding environment, filter it through all sorts of wacky filters, and then listen to it real-time? In essence, headphones with microphone, and echo, delay, chorus filters.
  2. jcsd
  3. Dec 28, 2013 #2
    It depends on what you mean by "real time". If you mean almost real time (extremely small delay), then that should be entirely possible. I'm sure that there are high-end guitar filters, for example, that fit the bill.

    If you mean truly real time, however, then we have an interesting question. The speed of light (and therefore electrical signals) is much faster than the speed of sound, so if the signal is sent across a long enough distance from the source to the listener (headphone wires, perhaps), and if the filter circuitry is sufficiently fast, then the sound can be sent not only in real time, but it can reach the listener before the original sound waves do.

    But, if the recording device close to the listener, or is recording sounds from all directions (not a single source), I don't think it is possible.
  4. Dec 28, 2013 #3


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  5. Dec 28, 2013 #4


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    Absolutely. Not only possible, it happens in studios and during recording sessions with microphones connected to mixers and effects. I've heard it myself. Usually you want to minimize the sound from the environment though, since this is considered as noise. This noise signal can also be used for noise cancellation systems (which lisab mentioned above). One of my projects at university was actually design of noise cancellation filters.

    "Real-time" will be almost real-time, though, since A/D & D/A conversions and filters all contribute to the so-called latency (signal delay).

    Sometimes amplifiers may even pick up radio signals. I've listened to radio through old guitar amplifiers. It's not the best reception, but it's hilarious to hear :biggrin:.
    Last edited: Dec 28, 2013
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