[sdiy] Phase Alignment vs. Frequency/Timing vs. Human Hearing

[Tom Wiltshire]

My guess is that it becomes difficult to tell at the point at which the frequencies start to be perceived as audio - e.g. when your modulation starts to turn into FM, since we don't hear phase directly for frequencies, but we can hear time differences for things that are perceived as separate events (like individual beats). 10 Hz is 600 BPM, so I'd expect that it'd start to get hard to tell at x4 or x8 of your 130BPM.

I don't know of any "accepted" frequency even for where "tempo" turns into "frequency". They overlap a bit, especially in the age of the stutter edit.

What have you discovered so far?

Tom

On 6 Nov 2014, at 19:01, Justin Owen <juzowen at gmail.com> wrote:

> Evening/Morning all..,
> 
> I'm wondering if anyone can help with this...
> 
> Imagine you have a standard 4/4 click track at an arbitrary tempo - let's say 130 BPM (approx. 2Hz). Let's also say you have a waveform of some sort being modulated by the Cutoff of a filter, using an LFO which is operating at the same clock tempo.
> 
> At that clock speed you can double, triple, possibly even quadruple the tempo of the modulation LFO and - most likely - you'll still be able to tell that the modulation tempo/frequency is a multiple of the clock frequency and that the two are in phase/sync.
> 
> However - the higher the modulation frequency - the harder it becomes to tell whether the clock and the modulation are in time/multiples of each other...
> 
> So - is there an accepted point or frequency/tempo range that the average human ear can no longer tell when two signals like the above are synced?
> 
> I guess a similar scenario would stand for two signals that were in sync - but where one was shifted in phase. At some point, for faster signals, it would be too hard to tell whether they were in or out of phase.
> 
> Hope that makes sense... :/ Thanks!
> 
> - Justin
> 
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