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SPL and the room


Nifkin
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Mate always quotes 60% of the sound is your room not the speakers , acoustics engineer

Does make a huge difference and now can listen at low or high levels ideal with giant speakers

Edited by triumph
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I'm intrigued by what's being said here, that the quality of the sound doesn't change in a given room regardless of SPL. We've mention room modes, which are usually restricted to frequencies lower than 200hz, but what about high frequency reflections? Do these not change depending on sound pressure? The idea of near field listening, with relatively low volume levels but adequate for the listening position seems to suggest that there is at least an attempt to remove the room conditions from the equation to a degree. If the character of the in-room sound is the same at any volume level, how can this work? 

Do acoustic engineers not take into account preferred listen volume levels when treating a room?

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8 hours ago, triumph said:

Mate always quotes 60% of the sound is your room not the speakers , acoustics engineer

Does make a huge difference and now can listen at low or high levels ideal with giant speakers

It's not quite clear to me what you're saying here? Is there a particular change you're referring to in the second sentence?

The use of DSP in my system allows me to listen to a full-range sound in my modestly sized room. Speaker size often relates to bass extension...

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9 minutes ago, Nifkin said:

 but what about high frequency reflections? Do these not change depending on sound pressure?

I don't believe so. 

9 minutes ago, Nifkin said:

The idea of near field listening, with relatively low volume levels but adequate for the listening position seems to suggest that there is at least an attempt to remove the room conditions from the equation to a degree. If the character of the in-room sound is the same at any volume level, how can this work? 

Being closer to a loudspeaker will increase the amplitude of the signal that goes directly from the speaker drivers to the listeners ears relative to the amplitude of the signal reflected from the room boundaries and other objects in the room. Keep the listening position fixed and vary the volume and this ratio will also remain fixed though.

This is unrelated to the room but I think we're also getting into the territory of limitations of loudspeakers as the volume is increased here... If you sit closer to a smaller speaker in a smaller room then you can listen at a decent volume without hitting output and performance limits of the loudspeaker. Place the same speaker in a larger room and sit further away from it and you'll have to drive the speaker to get the same SPL at the listening position. This can result in distortion that does not sound good.

9 minutes ago, Nifkin said:

Do acoustic engineers not take into account preferred listen volume levels when treating a room?

l don't think so.

Edited by MartinC
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One aspect that does vary with SPL at the listening position is the relative sensitivity of human hearing as a function of frequency. As the volume is increased we become increasingly more sensitive at the frequency extremes relative to the midband, which can make deeper bass more prominent and the top end sound more detailed/exciting. At low volumes lower bass notes may even be below the threshold at which they are audible even though much of the frequency range can be heard. One consequence is that room modes at the lowest frequencies may not be audible at very low listening levels, but become so as the volume is increased. This could give the impression that the room modes are only being excited at higher volumes but it's a human hearing response effect rather than an in-room acoustic effect.

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31 minutes ago, MartinC said:

One aspect that does vary with SPL at the listening position is the relative sensitivity of human hearing as a function of frequency. As the volume is increased we become increasingly more sensitive at the frequency extremes relative to the midband, which can make deeper bass more prominent and the top end sound more detailed/exciting. At low volumes lower bass notes may even be below the threshold at which they are audible even though much of the frequency range can be heard. One consequence is that room modes at the lowest frequencies may not be audible at very low listening levels, but become so as the volume is increased. This could give the impression that the room modes are only being excited at higher volumes but it's a human hearing response effect rather than an in-room acoustic effect.

Hence the reason the Loudness button was invented!

Ok, so I can conclude that my idea of a 'hifi triangle' featuring kit+room+SPL doesn't work because quality of sound doesn't change at different listening volume levels, within rational limits.

Edited by Nifkin
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2 hours ago, Nifkin said:

Hence the reason the Loudness button was invented!

Ok, so I can conclude that my idea of a 'hifi triangle' featuring kit+room+SPL doesn't work because quality of sound doesn't change at different listening volume levels, within rational limits.

I think that the point of the sound not changing at different spls, is very much kit and volume  dependent.

With many amplifiers that measure well, once playing actual music, intermodulation distortion takes effect as volume increases, causing a loss of sound quality.

But this is both speaker and amplifier dependent, and it effects most systems, and if you understand what your listening for, and its easy to identify.

For instance, a system may well play some simple jazz or acoustic music well, but then you play music with more instruments playing together,  and the sound starts to collapse, it goes flat and lifeless, you may well blame a poor recording... 

But its likely your systems distorting 

There's that need to turn it up to hear more background and the background detail disappears as you do it.

 Much hifi kit is not what you think..

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If you push SPL too high, your ears will be driven into compression via the stapedius reflex. That will affect your perception of the sound.

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Thanks @Blzebub and @steve 57 both interesting points: I suspected that sound quality doesn't remain constant on a given system in a given room* across a full range of SPL levels, but didn't know how this could be explained: obviously at high SPL levels system distortion and the limitations of human hearing play a part.

*I'm talking average rooms here, as most people, even with a proper set up, don't have rooms acoustically designed to suit their set-up to perfection.

Edited by Nifkin
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8 hours ago, Nifkin said:

I'm intrigued by what's being said here, that the quality of the sound doesn't change in a given room regardless of SPL. We've mention room modes, which are usually restricted to frequencies lower than 200hz, but what about high frequency reflections? Do these not change depending on sound pressure? The idea of near field listening, with relatively low volume levels but adequate for the listening position seems to suggest that there is at least an attempt to remove the room conditions from the equation to a degree. If the character of the in-room sound is the same at any volume level, how can this work? 

Do acoustic engineers not take into account preferred listen volume levels when treating a room?

The impact of reflections gets worse as volume increases. But I don't see why acousticians should take the listening volume into account. Even if treated there's only so much volume a semi-echoic room can take. In an anechoic room you can blow up the speakers before the room starts being an issue.

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5 hours ago, steve 57 said:

With many amplifiers that measure well, once playing actual music, intermodulation distortion takes effect as volume increases, causing a loss of sound quality.

Are you referring to intermodulation distortion produced by the loudspeaker? Because if an amplifier measures well in terms of intermodulation distortion then the speaker is the limiting factor.

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6 minutes ago, tuga said:

The impact of reflections gets worse as volume increases. But I don't see why acousticians should take the listening volume into account. Even if treated there's only so much volume a semi-echoic room can take. In an anechoic room you can blow up the speakers before the room starts being an issue.

I was just wondering if acousticians ever do take listening volumes onto account: wasn't assuming they did.

And it make sense that high frequency reflections become more problematic at higher volumes.

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B&O's Geoff Martin has made an amazingly informative set of videos on the subject of acoustics -> https://www.youtube.com/channel/UCvERIJHbjGeG7Bj3xW-n7iA

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1 hour ago, tuga said:

The impact of reflections gets worse as volume increases.

In what way? I've not seen anything to suggest this is true myself but I'm open to learn :).

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