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Re: [AUDITORY] MIDI Drum Pads: Delay and temporal resolution

Hi Benjamin,

On Jun 17, 2013, at 6:19 PM, Benjamin Schultz <benjamin.schultz@xxxxxxxxxxxxxx> wrote:

I am currently looking at purchasing a MIDI Drum Pad for experimental research involving finger tapping. There appears to be very little information regarding how much of a time delay there is between the pads being tapped and the sound being produced (via external MIDI devices or the drum pad’s internal sequencer).

To address the question of what is the total input-output latency of that system one has to consider that this varies quite a lot between different setups. The overall latency might consist of:

* The scanning interval of the hardware controller buttons
* The latency of the hardware midi controller for MIDI Out
* The MIDI protocol latency 
* Additional latency that will be introduced when transporting MIDI over USB.
* Additional host driver latency (if you use a computer as sound generator)
* …

Although there are some sources out there like (http://www.soundonsound.com/sos/sep02/articles/pcmusician0902.asp) that tried to measure these individual factors, you better go for a measurement of the overall input-output latency. I recently watched a session about Android low delay audio from this years Google I/O

They actually had a nice setup to measure the overall latency. They've used a 2ch scope and put one channel on the output audio and the other to a self made circuit that measures light intensity of a hardware led on that device. In your case you could just put a pressure sensor (piezo) on one of the drum pads to measure the latency in a similar fashion.

I’m looking to have the smallest time delay possible (sub-millisecond would be ideal). Does anyone have any advice about the best device to use and what kinds of time delays I should expect from the device? Their unit of pulses per quarter note does not appear to be very informative.

I would not be surprised if most of these drum pads will have delays in the range of 3-6 ms. With MIDI there is very little change you can get into the sub ms range. This might be the reason why most drum triggers are still using analog transmission.


Dipl.-Ing. Fabian-Robert Stöter

International Audio Laboratories Erlangen (AudioLabs) 
Universität Erlangen-Nürnberg & Fraunhofer IIS, Audio & Multimedia
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91058 Erlangen
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