Whistle effect

stevesy · February 12, 2018, 1:01pm

Hi, I’m new to the Audacity forums and Audacity. I’d like to generate a complex tone that sounds like a whistle, or alter an existing one to make it sound like a whistle. I’ve had a look at the manual here but could do with some help. What I’m basically trying to do is make a DTMF tone sound like a whistle. Can you tell me if this is possible and how I might go about it? Help appreciated, thanks.

Audacity 2.2.1, Windows 10.

steve · February 13, 2018, 1:59am

That would have to assume that the combination of frequencies in a DTMF tone can be produced by a whistle, which is probably not the case.
What’s the purpose of this - what’s it for?

stevesy · February 13, 2018, 12:37pm

Yeah it would be difficult to do without extended vocal technique or something like that. Say if I have an mp3 file of a dtmf tone, would there be a way to modify it to sound like a whistle? I’m working on an electronics project - trying to turn leds on and off using whistle commands.

steve · February 13, 2018, 1:15pm

I think you’re approaching it the wrong way.

How does the “receiver” decode the whistle commands?

If you don’t know (and understand) the algorithms that it is using, then I think your only option is to use “sampling” rather than “synthesis”. That is, “record” some actual whistle commands that work, then simply play them back as required.

If you do know and understand the algorithms that it is using, then rather than emulating the whistle sound, you should be generating the specific patterns that the algorithm is looking for. For example (and hypothetically), if it is looking for the sound to contain uncorrelated narrow-band noise in the frequency range 2 to 4 kHz, then your synthesis algorithm will need to match that and add that specific type of noise. The “encoding” algorithm of the transmitter and the decoding algorithm of the receiver need to match.

stevesy · February 13, 2018, 6:23pm

steve:

stevesy:

I’m working on an electronics project - trying to turn leds on and off using whistle commands.

I think you’re approaching it the wrong way.

How does the “receiver” decode the whistle commands?

If you don’t know (and understand) the algorithms that it is using, then I think your only option is to use “sampling” rather than “synthesis”. That is, “record” some actual whistle commands that work, then simply play them back as required.

If you do know and understand the algorithms that it is using, then rather than emulating the whistle sound, you should be generating the specific patterns that the algorithm is looking for. For example (and hypothetically), if it is looking for the sound to contain uncorrelated narrow-band noise in the frequency range 2 to 4 kHz, then your synthesis algorithm will need to match that and add that specific type of noise. The “encoding” algorithm of the transmitter and the decoding algorithm of the receiver need to match.

I’m very new to signal processing steve. Goertzel, FFT etc are beyond me at the moment. I’m using the MT8870 decoder module (really cheap) which I think uses the Goertzel algorithm for DSP. Making the DTMF tone into a whistle was more of an experiment I wanted to try. Ultimately what I want to achieve is to be able to detect pure tone (sine wave) frequencies, rather than dual tone.