• Re: [Generative music using Isadora](/topic/4781/generative-music-using-isadora)

    Re: [Generating a Sine Sound Wave](/topic/2205/generating-a-sine-sound-wave)

    Hi,

    I stumble over these older discussions above on generating sound, but couldn't find the (perfect) solution there.

    I wish to make an installation in which a 25Hz frequency gets manipulated by movement and I would love to not have to 'out-source' the frequency generator. I of course have the option to send i.e OSC to another program (such as Abelton Live), but I feel for such a rather small task of sound generation I would like to not involve an extra program. I am thus looking for a Isadora intern solution.

    In one of the older threads I found the option to just play a recorded frequency sound file and manipulate this frequency via the replay speed, this is an option, but I still would enjoy being able to define the frequency in Isadora and maybe also to know to which frequency I manipulate the sound signal.

    I couldn't find any Audio Plugins for Windows (and Isadora 3) that generate a tone. So I am wondering either if somebody knows a audio Plugin that could help me with this task or has another suggestion?

    (I know there have been discussion for version 3 that a tone generator would be release, but I don't think there is one yet... at least I didn't found one....?)

    Thanks in advance!

  • Tech Staff

    @ari said:

    I found the option to just play a recorded frequency sound file and manipulate this frequency via the replay speed

     This is still your best option if you want to stay Isadora-native. There is not a tone-generator plugin.


    Here's a reddit post that gives a formula for calculating the pitch change based on the speed change

    s = 2^(t/12)
    Where t is the number of semitones you want to transpose. And s is the playbackspeed you need to play the clip at to get the desired pitch.
    The other answers suggesting to look for a lineair pattern won't get you anywhere close.
    A simple example is playing a clip at 200% will transpose it 1 octave up but playing it at 300% will be 1.5 octaves up. You'll have to play it back at 400% to get 2 octaves higher than the original


    A second person wrote:

    2^(x/12) (*100 for %) where x is the number of semitones. X is either positive if you're going up in pitch or negative if you're going down. This is for equal temperament, not just temperament.

    A third person wrote:

    Conversely, if I play the clip back at 137% speed, how much does the pitch go up?
    change in semitones = −12log2(t1/t2) where t1 = tempo before change and t2 = tempo after change


  • @woland Thank you very much for the fast reply!

    I am trying to wrap my head around the formula and how to apply it. I though can't yet see how the frequency in Hertz is changing (as I am not thinking in semitones).... not sure if I am just overlooking sth.

    Basically as an example I would like to know if I play 25 Hertz in 200% speed, how many Hertz do i get ....?

  • Tech Staff

    @ari said:

    can't yet see how the frequency in Hertz is changing (as I am not thinking in semitones)

    This may be helpful 

    Convert Hz to Semitones

    Chart of Musical Notes as frequencies 1

    Chart of Musical Notes as frequencies 2 (It has a helpful note at the bottom: "To get the semitone frequency, multiply the note below it by 12√2 or 1.0595.")

    I am not a musician or a mathemetician but my Google-fu is strong.

  • Tech Staff

    Also, if memory serves, the incredibly brilliant @Maximortal made an Isadora-based Theremin or synth a few years ago. Maybe Maxi can help out with some insight.

    Best wishes,

    Woland


  • https://www.meldaproduction.co...

    https://www.meldaproduction.co...

    perhaps what you are looking for?

    best

    Jean-François