4 ms·

Delay compared to what? Video? I doubt normal stereo audio files are out of sync.

by gsich 5y ago

jacquesm 5y ago
The article is quite fluffy, but from what I gather it is about the difference in arrival time when a sound is perceived through multiple filters for different frequency bands, each of which has a programmable delay. One possible application for something like this would be to design a loudspeaker where the time-of-flight of the soundwave travelling from a tweeter to the listener would be the same as the same sound sent from a midrange speaker. Most designs do not adjust for such differences. The more interesting version - to me, at least - would be where you compare between the two arrivals at your left and right ear, which can do very small fractions of that even with relatively high pitched sounds allowing for sound source location based on phase.
- tuatoru 5y ago
  > One possible application for something like this would be to design a loudspeaker where the time-of-flight of the soundwave travelling from a tweeter to the listener would be the same as the same sound sent from a midrange speaker. Most designs do not adjust for such differences. Most designs, true. Very high-end speakers do sometimes incorporate all-pass filters in parts of their crossovers to compensate for the set-back of the apparent sound source in woofers. But very few people tilt their speakers so that the distance from the midrange and woofer to their ears is exactly the same as that from the tweeter at the listening position, and getting complicated crossovers to be reliable at 100 watt power levels is very expensive. Time-of-flight compensation is trivial in the digital domain, so some active crossovers (which operate on line level signals, before the power amplifiers) also do this. The downside, of course, is needing one power amplifier per speaker cone, not just one per box, and the extra wires if using separate amplifier blocks rather than active speakers. The consensus seems to be that it's not worth the trouble in ordinary listening situations.
  - jacquesm 5y ago
    The one-amp-per-device is actually quite common in monitor speakers.
- gsich 5y ago
  I think most speaker setups have a microphone that you place where the listener is to calibrate. Don't know if that involves delay measurements.
  - jacquesm 5y ago
    There was the Philips concept called MFB which integrated an accelerometer into the low frequency speakers in order to match the desired waveform with the one that actually went out. Quite a neat little concept, they are still somewhat popular in the HiFi scene. The microphone systems mostly calibrate for frequency loss across the spectrum, time-of-flight adjustments I haven't seen but it's quite possible they're out there somewhere, but they would require a pretty nifty delay mechanism or a digitization step and then turning the signal yet again back into analog which would probably cause more problems than it solved.

Delay compared to what? Video? I doubt normal stereo audio files are out of sync.

by gsich 5y ago

Delay compared to what? Video? I doubt normal stereo audio files are out of sync.

The article is quite fluffy, but from what I gather it is about the difference in arrival time when a sound is perceived through multiple filters for different frequency bands, each of which has a programmable delay. One possible application for something like this would be to design a loudspeaker where the time-of-flight of the soundwave travelling from a tweeter to the listener would be the same as the same sound sent from a midrange speaker. Most designs do not adjust for such differences. The more interesting version - to me, at least - would be where you compare between the two arrivals at your left and right ear, which can do very small fractions of that even with relatively high pitched sounds allowing for sound source location based on phase.

tuatoru 5y ago
> One possible application for something like this would be to design a loudspeaker where the time-of-flight of the soundwave travelling from a tweeter to the listener would be the same as the same sound sent from a midrange speaker. Most designs do not adjust for such differences. Most designs, true. Very high-end speakers do sometimes incorporate all-pass filters in parts of their crossovers to compensate for the set-back of the apparent sound source in woofers. But very few people tilt their speakers so that the distance from the midrange and woofer to their ears is exactly the same as that from the tweeter at the listening position, and getting complicated crossovers to be reliable at 100 watt power levels is very expensive. Time-of-flight compensation is trivial in the digital domain, so some active crossovers (which operate on line level signals, before the power amplifiers) also do this. The downside, of course, is needing one power amplifier per speaker cone, not just one per box, and the extra wires if using separate amplifier blocks rather than active speakers. The consensus seems to be that it's not worth the trouble in ordinary listening situations.
- jacquesm 5y ago
  The one-amp-per-device is actually quite common in monitor speakers.
gsich 5y ago
I think most speaker setups have a microphone that you place where the listener is to calibrate. Don't know if that involves delay measurements.
- jacquesm 5y ago
  There was the Philips concept called MFB which integrated an accelerometer into the low frequency speakers in order to match the desired waveform with the one that actually went out. Quite a neat little concept, they are still somewhat popular in the HiFi scene. The microphone systems mostly calibrate for frequency loss across the spectrum, time-of-flight adjustments I haven't seen but it's quite possible they're out there somewhere, but they would require a pretty nifty delay mechanism or a digitization step and then turning the signal yet again back into analog which would probably cause more problems than it solved.