An Enticing Marketing Story, Theory Without Measurement?

[svart-hvitt]

Anechoic chambers are unpleasant places to spend time in, can be quite disconcerting.

Without sound or with sound of music?

 

[Kal Rubinson]

Without sound or with sound of music?

Both.

 

[DDF]

I think I am of the opinion (note: OPINION as opposed to a scientifically based statement) that much music would sound really great in an anechoic chamber.

Take it from someone that worked for years in anechoic chambers: music sounds terrible in them. The instant decay into nothingness is disconcerting and unnatural. It even raises new SNR quandaries: you can actually hear your heart or blood pumping through your veins.

 

[Ultrasonic]

Look at Section 7.4.7 "Floor Reflections: a Special Case?". There is evidence that humans evolved with something always below their feet and when acoustical evidence of it is removed they may not approve. Human adaptation cannot be ignored. However, in the modal and adjacent boundary region (below about 500 Hz in domestic rooms) judicious EQ can be beneficial. Chapters 8 and 9 focus on this region.

Firstly, it is a privilege to see you posting here Dr Toole. Thank you.

I was interested to read your comment in bold above. I've most often seen the advice to restrict room curve related EQ to below the Schroeder frequency (as indeed some have posted in this thread) but here I believe you are advocating going rather higher in frequency. I appreciate I'd find more info. if I were to buy your book but I wondered if you might be willing to expand on this a little more here?

In my own humble system I have been experimenting with using a miniDSP to do a combination of two things: room mode attenuation below about 200 Hz and attempting some speaker output correction above around 500 Hz (based on gated speaker output measurements).

 

[Cosmik]

Re. floor reflections, does anyone feel that the sound of a companion's voice changes as they walk up stairs (a rather different 'floor') or that they fail to recognise someone's voice when leaning over a balcony or standing on a narrow bridge, or up a tree? I can't say that I ever notice(d) anything untoward in any of these situations.

The hobby of audio measurements is a constant case of "Wow, just look at that peak/dip. If I hadn't measured it I would never have known it was there!". Measuring things in audio is like owning a special pair of goggles that reveals to you a secret world hidden to everyone else. They go about their daily lives completely unaware that they have just walked through a 10dB dip centred on 320Hz. If only they knew, they would demand that something be done about it.

 

[svart-hvitt]

Take it from someone that worked for years in anechoic chambers: music sounds terrible in them. The instant decay into nothingness is disconcerting and unnatural. It even raises new SNR quandaries: you can actually hear your heart or blood pumping through your veins.

Can you still hear your heart and blood running when music plays?

I thought it would be strange when there’s no sounds playing, but pieces falling somewhat in place if certain recordings with reflections are playing.

I have read about people complaining about silence in a small anechoic room. But we do now that small closed rooms are intimidating as well. I thought maybe the silence factor went away when playing say a church choir (for its recorded reflections).

 

[DDF]

Can you still hear your heart and blood running when music plays?

Its easily masked by music or speech, but evident during complete gaps because good anechoic chambers are shock and acoustically isolated, leading to their extremely low background noise levels. I typically worked in a moderate sized anechoic chamber (good down to 100 Hz) but at times with a large one (equal or larger than the NRC's). It was the second one that allowed that inner workings detection, and it was due to its extremely low external noise floor more than it's lack of reflection.

The smaller room never bothered me, but the big room was uncomfortable.

 

[DDF]

The hobby of audio measurements is a constant case of "Wow, just look at that peak/dip. If I hadn't measured it I would never have known it was there!". Measuring things in audio is like owning a special pair of goggles that reveals to you a secret world hidden to everyone else. They go about their daily lives completely unaware that they have just walked through a 10dB dip centred on 320Hz. If only they knew, they would demand that something be done about it.

It can be that or it can be like a subet of conversations in this thread where people point out that double blind scientific experiments have found that the floor bounce changes the timber of the sound, and then participants respectfully discuss whether its more accurate to have it, or not, and for which use cases.

I think its logical (I've previously explained why) to leave in the floor bounce for closed mic small ensemble pieces meant to be enjoyed live in a small venue, not have it for music that's meant to be listened to live in a large auditorium.

I'd hate to see this site devolve into Twitter where cheap pot shots at perceived subjectivists or "other groups" are used to generate a cascade of "likes". Way too much of that going on.

 

[amirm]

I think I am of the opinion (note: OPINION as opposed to a scientifically based statement) that much music would sound really great in an anechoic chamber.

Try to listen to someone sing outdoors versus indoor. You will change your mind.

 

[svart-hvitt]

Try to listen to someone sing outdoors versus indoor. You will change your mind.

Natural voice unamplified is one thing.

When I was in a wedding, quite free field, it struck me how clear and good the sound was, going through microphone and speakers.

So from personal experience I have yet to experience any strangeness outdoors as soon as sound goes through a reproduction chain.

 

[Ron Texas]

Try to listen to someone sing outdoors versus indoor. You will change your mind.

If I sang outdoors someone would call 911.

 

[Floyd Toole]

Firstly, it is a privilege to see you posting here Dr Toole. Thank you.

I was interested to read your comment in bold above. I've most often seen the advice to restrict room curve related EQ to below the Schroeder frequency (as indeed some have posted in this thread) but here I believe you are advocating going rather higher in frequency. I appreciate I'd find more info. if I were to buy your book but I wondered if you might be willing to expand on this a little more here?

In my own humble system I have been experimenting with using a miniDSP to do a combination of two things: room mode attenuation below about 200 Hz and attempting some speaker output correction above around 500 Hz (based on gated speaker output measurements).

The Schroeder frequency, as indicated by Schroeder himself, was created in the context of large performance spaces with significant diffusion, not small, relatively dead listening rooms. However the principle still applies but starting at a higher frequency than the one calculated. See Figure 6.2 in the 3rd edition of my book. It is not a well defined frequency in any room; it really indicates how much overlap there is between and among room resonances. I chose to call it the transition frequency. Below this frequency judicious equalization can be used to address individual prominent room resonances, but it is only functional at the point of measurement - the prime listening location. All other seats will be different. This is the reason why multiple subwoofers are advantageous (Chapter 8), along with the greatly increased efficiency.

At the upper range of this frequency range and above, up to a few hundred Hz, we encounter adjacent boundary effects and these can be addressed by equalization - See Chapter 9.

 

[Floyd Toole]

Try to listen to someone sing outdoors versus indoor. You will change your mind.

As was pointed out in the paper on the audibility of resonances, our sensitivity to resonances increases greatly in reflective sound fields. Each reflection is a repetition, giving the hearing system more "looks" at the sound from the source. It means that the timbral richness of live sound sources is increased in reflective spaces, compared to sterile anechoic or outdoor spaces. Of course, for sound reproduction there is a downside in that resonances in loudspeakers will be more audible

 

[RayDunzl]

How does listening with a noise blocking/sound isolating IEM compare to listening in an anechoic chamber?

 

[Kal Rubinson]

Re. floor reflections, does anyone feel that the sound of a companion's voice changes as they walk up stairs (a rather different 'floor') or that they fail to recognise someone's voice when leaning over a balcony or standing on a narrow bridge, or up a tree? I can't say that I ever notice(d) anything untoward in any of these situations.

I guess you are less neurotic than I am. Acoustic ambiance is one of the first things I notice when I enter a novel environment.

 

[Kal Rubinson]

Try to listen to someone sing outdoors versus indoor. You will change your mind.

Yes. It is interesting to note that, prior to the modern age, people took advantage of unique sites as amphitheaters and actually mimicked them to construct similar spaces.

 

[Cosmik]

I guess you are less neurotic than I am. Acoustic ambiance is one of the first things I notice when I enter a novel environment.

I'm not saying that I don't notice the acoustic environment; I'm saying that it doesn't affect the sound (as perceived by me) of the source.

 

[Kal Rubinson]

I'm not saying that I don't notice the acoustic environment; I'm saying that it doesn't affect the sound (as perceived by me) of the source.

Hmmm. Once I notice it, I cannot but attend to how it changes my perception of the source.

 

[DDF]

Hmmm. Once I notice it, I cannot but attend to how it changes my perception of the source.

https://en.wikipedia.org/wiki/Soundscape
Acoustic ecology is a discipline focused very much on this

 

[amirm]

Natural voice unamplified is one thing.

When I was in a wedding, quite free field, it struck me how clear and good the sound was, going through microphone and speakers.

Well, one thing you get outside is bass with no resonances/modes. You need tons of power though but it is the cleanest. Outside of that, it can sound dull and uninteresting if it is completely open space.