Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Merlijn van Veen]

Hi everybody,

I wrote an article about the audibility of phase shift and how in typical sound systems the harmonics of low frequency sources e.g. electric bass guitar, lead the fundamental by as little as 20 ms (7 meters) or more. You can read it at the link below.

Regards,

Merlijn

https://www.merlijnvanveen.nl/en/study-hall/100-the-harmonics-lead-the-fundamental

[John Roberts {JR}]

Hi everybody,

I wrote an article about the audibility of phase shift and how in typical sound systems the harmonics of low frequency sources e.g. electric bass guitar, lead the fundamental by as little as 20 ms (7 meters) or more. You can read it at the link below.

Regards,

Merlijn

https://www.merlijnvanveen.nl/en/study-hall/100-the-harmonics-lead-the-fundamental

This reminds me of the contentious debate about audibility of absolute polarity decades ago.

When you speak of harmonics leading the fundamental are you talking about the arrival time for initial transient or the relatively steady tone as the plucked string decays? For the steady state part of the waveform it's relative whether the overtones are leading or lagging. For the initial attack it can make a difference regarding localization. 

Phase relationships can affect the shape and symmetry of the compound waveforms. In theory this should not make a difference, but it's easy to imagine asymmetrical signal limits in our mechanical system (ears).

Human hearing is reported to be most sensitive at perceiving such errors in vocals.

JR

PS: I do not claim to hear any of this stuff...

[Art Welter]

Hi everybody,

I wrote an article about the audibility of phase shift and how in typical sound systems the harmonics of low frequency sources e.g. electric bass guitar, lead the fundamental by as little as 20 ms (7 meters) or more. You can read it at the link below.

Regards,

Merlijn

     
Nice demo video!

In the article you wrote:

"That being said, I know of a few people that I hold in high regards e.g. Mauricio "Magu" Ramírez of Meyer Sound and François "Frankie" Desjardins of Solotech, that have been fortunate enough to actually hear real speakers with linear "flat" phase behavior from virtually DC to light."

You probably have listened to Sony MD 7506 headphones, in which case you also have been fortunate enough to hear real speakers with linear "flat" phase behavior over the audible range.

Listening back, even using the 7506 phones, I couldn't detect the phase shifts...

Art

[Phillip Ivan Pietruschka]

In the sound systems I have aligned for theatrical applications, I have noted a correlation between the systems with the most phase shift, or wraps, through the mid range, and those with the poorest dialog intelligibility. However, yes, correlation is not causation. There are at least a thousand variables not controlled for. What does one do with an observation like that? I dunno, do what one can to avoid purple speakers perhaps.

[Merlijn van Veen]

This reminds me of the contentious debate about audibility of absolute polarity decades ago.

When you speak of harmonics leading the fundamental are you talking about the arrival time for initial transient or the relatively steady tone as the plucked string decays? For the steady state part of the waveform it's relative whether the overtones are leading or lagging. For the initial attack it can make a difference regarding localization. 

Phase relationships can affect the shape and symmetry of the compound waveforms. In theory this should not make a difference, but it's easy to imagine asymmetrical signal limits in our mechanical system (ears).

Human hearing is reported to be most sensitive at perceiving such errors in vocals.

JR

PS: I do not claim to hear any of this stuff...

Hi John,

AFAICT the sequence between the harmonics' transients and steady states is primarily a property of the instrument or source. The speaker (as one of the links in the signal chain) doesn't differentiate. The group delay of the speaker is technically non-linear behavior and changes the natural order of things. Being most severe in LF range I can imagine a noticeable change without it.


Verzonden vanaf mijn iPad met Tapatalk

[Merlijn van Veen]

In the sound systems I have aligned for theatrical applications, I have noted a correlation between the systems with the most phase shift, or wraps, through the mid range, and those with the poorest dialog intelligibility. However, yes, correlation is not causation. There are at least a thousand variables not controlled for. What does one do with an observation like that? I dunno, do what one can to avoid purple speakers perhaps.

As non-linear behavior, less group delay is off course commendable but should be realized within reason. With more than one speaker in installs, relative phase offset between various makes and models is the more likely culprit for impaired intelligibility.

In this corner of the world, most theaters' fill speakers exhibit different phase behavior in comparison to the main speakers which can be treated most of the with careful use of all-pass filters.


Verzonden vanaf mijn iPad met Tapatalk

[Merlijn van Veen]

     
Nice demo video!

In the article you wrote:

"That being said, I know of a few people that I hold in high regards e.g. Mauricio "Magu" Ramírez of Meyer Sound and François "Frankie" Desjardins of Solotech, that have been fortunate enough to actually hear real speakers with linear "flat" phase behavior from virtually DC to light."

You probably have listened to Sony MD 7506 headphones, in which case you also have been fortunate enough to hear real speakers with linear "flat" phase behavior over the audible range.

Listening back, even using the 7506 phones, I couldn't detect the phase shifts...

Art

Hi Art,

Thanks for the compliment and the revealing tip!

I'm anxious to experience those cans with renewed interest :-)


Verzonden vanaf mijn iPad met Tapatalk

[Peter Morris]

This reminds me of the contentious debate about audibility of absolute polarity decades ago.

When you speak of harmonics leading the fundamental are you talking about the arrival time for initial transient or the relatively steady tone as the plucked string decays? For the steady state part of the waveform it's relative whether the overtones are leading or lagging. For the initial attack it can make a difference regarding localization. 

Phase relationships can affect the shape and symmetry of the compound waveforms. In theory this should not make a difference, but it's easy to imagine asymmetrical signal limits in our mechanical system (ears).

Human hearing is reported to be most sensitive at perceiving such errors in vocals.

JR

PS: I do not claim to hear any of this stuff...

Nice article & video Merlijn (like all your work).

I have also been doing a little work on this subject.

I posted plans for a speaker I built on Soundforums.net https://soundforums.net/threads/12075-60-Degree-DIY-Mid-Hi

It has an almost perfect impulse response. The amplitude and phase response is almost perfectly flat from about 200Hz up. It will produce a reasonable looking square wave from about 100Hz, both on and off axis …. And it goes LOUD

To my ear the flat phase response version doesn’t really sound any better, just more real.  It’s like the difference looking out through a window with clean class and opening the window (no glass) if that make sense. You notice that with a minimum amount of phase wrap the drum and bass sounds are very “tight” and have a lot of impact.

My experience even though the phase response was not perfectly flat to DC matched what Mauricio and François described.

[Jim McKeveny]

You notice that with a minimum amount of phase wrap the drum and bass sounds are very “tight” and have a lot of impact.

This is why higher-order bandpass woofer designs fail to pass sonic muster.

[John Roberts {JR}]

To my ear the flat phase response version doesn’t really sound any better, just more real.  It’s like the difference looking out through a window with clean class and opening the window (no glass) if that make sense. You notice that with a minimum amount of phase wrap the drum and bass sounds are very “tight” and have a lot of impact.

My experience even though the phase response was not perfectly flat to DC matched what Mauricio and François described.

Back decades ago when I was designing hifi gear, I used to joke if you can't hear the improvement through the screen door while standing in the yard, it isn't good enough. 

Subtle subjective phenomenon are always difficult to get a handle on.

One test I've heard speaker designers use is to loop through a system for multiple passes. Modern digital recorders should be linear enough, so the mic becomes the only other variable and mics are generally better than speakers.  After running a recording through a system (better yet while in an anechoic environment) for multiple passes, any errors will accumulate and become easier to identify.

A square wave seems like a difficult gold standard. Do you see Gibbs phenomenon due to LPF scrubbing off upper harmonics?

JR

[ProSoundWeb Community]