Low listening level measurement.

[Bill Gobby]

Is there a measurement or rating in loudspeaker spec. that indicates a given speakers low listening level abilities for different speaker comparisons.
Ottguit

 

[markw]

Aside from sensitivity/efficiency which can suggest how relatively "loud" they will play with certain power levels, I can't think of anything that would compare sound quality. That's more of a preference issue.

 

[WaynePflughaupt]

Is there a measurement or rating in loudspeaker spec. that indicates a given speakers low listening level abilities for different speaker comparisons.
Ottguit

Not that I’ve ever heard of, and for good reason: A speaker’s sound quality has no relevance to average or low listening levels. IOW, reducing the volume isn’t going to make an excellent speaker sound like poop, nor will it make a poop speaker suddenly sound excellent. The only issue with low listening levels is a universal one that stands regardless of speakers in use, in that our ears don’t hear the treble and bass as well at low levels and may need to be boosted via tone controls.

Regards,
Wayne A. Pflughaupt

 

[Swerd]

Is there a measurement or rating in loudspeaker spec. that indicates a given speakers low listening level abilities for different speaker comparisons.
Ottguit

There isn't a simple number that can be included on a spec sheet to describe this, but there is a way to measure and display what you seem to be asking about.

Speakers produce sound straight ahead (on-axis) and at varying angles off-axis. This can be measured with a microphone at the same distance but at several different locations, on-axis and at several different angles off-axis. These measurements can be shown as multiple frequency response curves.

Here is an example for a Dynaudio Confidence C4 speaker http://www.soundstagenetwork.com/measurements/dynaudio_confidence_c4/

The first graph shows 3 traces measured on-axis and at 15° and 30° off-axis.

The second graph show 3 more traces measured at 45°, 60° and 75° off-axis

Notice how the curve is fairly level, even at higher frequencies, until the microphone is far off-axis. This results in sound that disperses well throughout the room, and sounds much better than a speaker that beams sound in a narrow pattern, especially at low volumes.

This wide dispersion is spoken of as "power response", and contrasts with a speaker's sensitivity rating which is measured at 1 meter away from a speaker, on-axis, with a 2.83 volt (1 watt if the speaker is 8 ohms) signal. A speaker with good sensitivity on-axis can still sound poor if it's power response is low.

 

[markw]

One thing about those, and all response curves I've noticed: They always seem to be centered somewhere between 80 - 90 db. Depending on one's interpretation of "low levels", this might be somewhat high.

I tend to think that the response might be somewhat different if it were measured at a lower level and, also taking into account Wayne's observation about our hearing abilities at lower levels, I think these curves might not really be too helpful for this situation. it might be more useful for "normal" listening levels.

 

[Swerd]

One thing about those, and all response curves I've noticed: They always seem to be centered somewhere between 80 - 90 db. Depending on one's interpretation of "low levels", this might be somewhat high.

I get what you're suggesting. All those curves were measured with 2.83 volts input with a microphone 1 meter away at various angles. That's not a large signal. You're wondering if the profile will be qualitatively different at a lower SPL.

I tend to think that the response might be somewhat different if it were measured at a lower level and, also taking into account Wayne's observation about our hearing abilities at lower levels, I think these curves might not really be too helpful for this situation. it might be more useful for "normal" listening levels.

Look at a single frequency, such as 1 kHz. On-axis it is about 89 dB (by eyeball estimation). At 30° off-axis its close at about 87-88 dB, 86 dB at 45°, 85 dB at 60°, and about 81 dB at 75°. If you start at a lower level, say 70 dB on-axis, the other off-axis responses will still be quieter by similar margins. So they can be informative regardless of the SPL level.

At low listening levels, the off-axis sound will become low enough to be poorly heard by the listener. Different speakers do better or worse at this. For this example I chose a speaker that has very good dispersion. Maybe I should have picked an example with poor power response.

 

[KEW]

I'm not sure how big of a factor it is, but Soundstage occasionally measures the deviation of the frequency response at different levels.
See Chart 4 at this link which has 3 graphs comparing FR at 70dB vs 90, 95, and 100dB, respectively.

http://www.soundstagenetwork.com/measurements/speakers/energy_rc_70/