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Re: low-latency audio I/O for Windows

We have used the M-Audio Delta 44 in ASIO mode with measured input to
output latency being approximately 5ms at 48KHz sampling rate. I
believe this can be brought down further (perhaps to less than 4ms)
using the 96KHz sampling rate.



Satrajit Ghosh

Research Scientist
Speech Communications Group
Research Lab of Electronics @ MIT

On 10/3/07, Kelly Fitz <kelly_fitz@xxxxxxxxxxx> wrote:
> I believe that RME still makes the lowest latency sound cards, but that
> they do not really approach the latency you require. The Hammerfall
> claims 1.5ms, but that is not throughput latency, it is the hardware
> latency. For simulating hearing aid algorithms, you need to pay that
> twice, once going in, and once going out.
> Moreover, most audio APIs that I know of use some kind of buffering, and
> you will therefore have those latencies on top of the sound card
> hardware latency. Other software systems like Max or Pd may impose
> additional buffering latencies.
> I am told that at the last IHCON, Giso Grimm (University of Oldenburg)
> demonstrated a system that achieved latency as low as 7ms, using a linux
> PC with ASIO drivers and the Hammerfall card. I think the system itself
> is described in
> Giso Grimm, Tobias Herzke, Daniel Berg, and Volker Hohmann. The Master
> Hearing Aid – a pc-based platform for algorithm development and
> evaluation. Accepted 2006 Acustica united with acta acustica, April 2006.
> I have never heard of a low-latency USB or 1394 interface, and I don't
> know enough about those protocols to know whether it is even achievable,
> but it is a reasonable question to ask. The low-latency RME cards are
> PCI or cardbus.
> If anyone can come up with a PC-and-soundcard-based system that has
> reliable and demonstrable <4 ms throughput latency, I'd love to know
> about it.
> HTH,
> Kelly
> Freed, Dan wrote:
> > Dear Auditory List Members:
> >
> > I'm looking for a low-latency audio interface device for use with
> > Windows computers.  The goal is to perform real-time signal processing
> > on the PC for the purpose of developing and testing hearing aid DSP
> > algorithms.  Consequently I need to keep the hardware-related signal
> > delay to a minimum.
> >
> > Unfortunately, manufacturers generally don't include latency in their
> > specifications, and tech support and sales people don't seem to have
> > latency information either.  So I'm hoping that people on this list can
> > point me at some acceptable devices.
> >
> > My target is a total input-to-PC-to-output delay <= 3 ms at 48 kHz.  I'd
> > prefer an external device (USB or FireWire).  Other desirable features
> > include a mic input, a headphone output, analog I/O level controls, and
> > support for a wide range of sampling rates (16, 24, and 32 kHz would be
> > nice).  But the critical feature is the low latency; I can work around
> > other limitations.
> >
> > Any suggestions will be greatly appreciated.  Thank you!
> >
> > Dan Freed
> > Senior Engineer
> > Dept. of Human Communication Sciences & Devices
> > House Ear Institute
> > 2100 W. Third St.
> > Los Angeles, CA  90057  USA
> > Phone: +1-213-353-7084
> > Fax: +1-213-413-0950
> > Email: dfreed@xxxxxxx
> >
> --
> Kelly Fitz, DSP Research Engineer
> Starkey Hearing Research Center