Why there is little focus on acoustics

[Hari Iyer]

Sorry for late response. Holiday season..

When i did my acoustic treatment, i made lot of research, contacted lot of HT room installers, probed them with the nrc of the material they use for specific frequency range. Found that the most of the installers didn't even have any clue. Finally found one guy who atleast shared the absorption coefficients and talked about placing alternate absorption and diffusion panels. Even then i must admit that i didn't get it fully right. My RT60 was around 300 to 200. Typical HT treatment. I couldn't complain as i solved my primary problem. Ability to play the music loud even when my daughter is studying next room or my wife is watching TV in living room. Bass was not controlled at all. But, i found a sweet spot of appx 1sqft after proper speaker placement. That's when i found the joy of the music. That was so blissful that i forgot my much highend gear and let it sleep for an year.

https://imgur.com/a/9f8Fe3T

Over the next 2 years, i tuned it a bit to add QRD diffusers to add more air and increase sweetspot. Added bass tubes which helped immensely on the ripple effect that bass energy had on midrange.

Again, i am just sharing my journey as i thought people can get more high quality music with way less money.

If you are using box speaker then getting RT60 below 200 could rob the music of harmonics and you could loose directional cues which is very important for sound localization and staging. This is evident from the waterfall plots which is very smooth and nice but could be sounding a bit lifeless. There is some resonance in the sub bass frequencies which needs taming. Overall a very good effort.

 

[Hari Iyer]

Does it influence the tone, timbre and transients? -- This is the biggest difference in treated rooms. Every reflection will create a ripple effect which can impact the tone, timbre and transients. It can add more energy or cancel out and create nulls depending on your listening position. I never realized earlier that treating for bass will help your midrange. Treating for higher frequency improves the clarity.

If you get a flat D50 curve from 100hz till 10khz then C50 will be flat too. I have noticed in my room D50 getting more effected in midrange than HF because of any treatment. Midrange frequency having longer wave length will requireca more denser treatment. For HF adding even a 4mm felt would suffice. I have tried to optimize my speaker placement and sitting position to address this. I may need to add some felt on my metal shoe rack which is adding a very strong reflection for my horn causing cancellation of my HF.

 

[matbhuvi]

If you are using box speaker then getting RT60 below 200 could rob the music of harmonics and you could loose directional cues which is very important for sound localization and staging. This is evident from the waterfall plots which is very smooth and nice but could be sounding a bit lifeless. There is some resonance in the sub bass frequencies which needs taming. Overall a very good effort.

Yeah..it has a very narrow sweet spot of 1 sqft. I am so used to studio monitors for a pretty long time (Neumann KEH120)...especially in untreated rooms in nearfield listening. My setup is dull outside of sweet spot. But, i wouldn't call it dull in sweet spot (with my limited experience). Getting acoustics completely right is insanely difficult. The sub bass resonances caused by room modes are super hard to treat unfortunately. I focussed on placement to get the right bass response in listening position rather than treatment.

 

[Passive_audio_enthusiast]

If you are using box speaker then getting RT60 below 200 could rob the music of harmonics and you could loose directional cues which is very important for sound localization and staging. This is evident from the waterfall plots which is very smooth and nice but could be sounding a bit lifeless. There is some resonance in the sub bass frequencies which needs taming. Overall a very good effort.

If you are sitting at the sweet spot, and if the room is dead(like it absorbs everything other than the direct wave), you hear all the directional cues that is present in the recording.

The room reflections enhances this effect, but now we are taking about something which isn’t part of the recording. Room reflections makes localization of the sound objects ambiguous if it’s already done well in the recording. It’s very easy to localize sound objects with a headphones than in a speaker(in a reflective room) for the same reason.

 

[Hari Iyer]

If you are sitting at the sweet spot, and if the room is dead(like it absorbs everything other than the direct wave), you hear all the directional cues that is present in the recording.

The room reflections enhances this effect, but now we are taking about something which isn’t part of the recording. Room reflections makes localization of the sound objects ambiguous if it’s already done well in the recording. It’s very easy to localize sound objects with a headphones than in a speaker(in a reflective room) for the same reason.

If you absorb the first reflection you will loose and NOT gain direction cues. Typically first reflection are diffused and not absorbed.

 

[Passive_audio_enthusiast]

If you absorb the first reflection you will loose and NOT gain direction cues. Typically first reflection are diffused and not absorbed.

what directional cues are you talking about here? The ones that are already in the recording will still be there. The ones that you loose by deadening the room would be the ones, that the room would have added to the sound from the speakers. in fact that’s not how the recording was intended. However one can prefer to have that effect, just like enjoying an effect generated by a DSP. You will still have directional cues in the recording within the head stage on a headphone. On a headphone, room is completely absent

 

[kratu]

Does it influence the tone, timbre and transients? -- This is the biggest difference in treated rooms. Every reflection will create a ripple effect which can impact the tone, timbre and transients. It can add more energy or cancel out and create nulls depending on your listening position. I never realized earlier that treating for bass will help your midrange. Treating for higher frequency improves the clarity.

I wouldn’t contest your findings. By tone and timbre, I meant naturalness. Say that we replace the speakers with an actual instrument, for example a tabla or human voice, will they sound less natural in an untreated room?

Maybe transients do get impacted because the reverb would seem to interfere with the synchronisation of the notes. Or at least the perception of pacing and rhythm.

 

[matbhuvi]

If you absorb the first reflection you will loose and NOT gain direction cues. Typically first reflection are diffused and not absorbed.

I read a good article in Audioholics about this topic. It talks about to choose diffusion vs absorption in first reflection based on room size and listening position. They even have a formula for that. Personally, i liked absorption. But, i went for diffusion to have a larger sweet spot.

Bottom line..use diffusion in small rooms and absorption in large rooms.

 

[matbhuvi]

I wouldn’t contest your findings. By tone and timbre, I meant naturalness. Say that we replace the speakers with an actual instrument, for example a tabla or human voice, will they sound less natural in an untreated room?

Maybe transients do get impacted because the reverb would seem to interfere with the synchronisation of the notes. Or at least the perception of pacing and rhythm.

If you have a glass wall behind speakers, you find some harshness in the vocals as well. You find it bit dry rather than lush. Notes will have some edges to it. It is very similar to having jitter in digital transport. This will also impact audio clues for separation.

 

[Hari Iyer]

what directional cues are you talking about here? The ones that are already in the recording will still be there. The ones that you loose by deadening the room would be the ones, that the room would have added to the sound from the speakers. in fact that’s not how the recording was intended. However one can prefer to have that effect, just like enjoying an effect generated by a DSP. You will still have directional cues in the recording within the head stage on a headphone. On a headphone, room is completely absent

There is zero direction cues on headphones as there is no room in the first place. Read white paper by Floyd Toole for more insight on this topic. Imagine speaker in an anechoic room and you close your eyes - you won't be able to locate in the room the source of sound. Only if you add some reflection you will be able to locate the source of sound. Similarly if you are in a big open ground and if you place a speaker there and close your eyes you won't be able to locate the speaker. Only with the reflection you can locate the source.

 

[Passive_audio_enthusiast]

Only if you add some reflection you will be able to locate the source of sound. Similarly if you are in a big open ground and if you place a speaker there and close your eyes you won't be able to locate the speaker. Only with the reflection you can locate the source.

You are basically suggesting that, we can locate the source of a sound more reliably in a room, if the room has more reverberation. I think it should be the other way around. If you don't mind can you post which part of Tooles book mentions this?

 

[sidvee]

There is zero direction cues on headphones as there is no room in the first place. Read white paper by Floyd Toole for more insight on this topic. Imagine speaker in an anechoic room and you close your eyes - you won't be able to locate in the room the source of sound. Only if you add some reflection you will be able to locate the source of sound. Similarly if you are in a big open ground and if you place a speaker there and close your eyes you won't be able to locate the speaker. Only with the reflection you can locate the source.

I am confused, all concerts are in huge stadiums with banks of speakers. You can always tell the direction from which the sound is coming from. I was in a wedding recently in a mini stadium sized ground and the hosts decided, unfortunately, to put the panditji's slokas on a large speaker system. I had to move away at-least 500m to avoid the unpleasant loudness coming from those speakers in such a large area - from a direct recitation into a mike/amplifier. I don't think direct sound needs any reflections, it will always have a directional cue of source. And I agree cues are added to a recording by the engineer based on required results. It is not always reflected sounds. Like capturing cues of the recording location - like a jazz club or a church or whatever by mike placement etc.
Anyways I belong to the camp that the room is the most important component in any domestic system, and its treatment or lack thereof will make a big difference in the sound regardless of large or small size. Yes too much or too less treatment will make or break the sound but that is like any other component of the system. There has to be some balance.
Cheers,
Sid

 

[kratu]

If you have a glass wall behind speakers, you find some harshness in the vocals as well. You find it bit dry rather than lush. Notes will have some edges to it. It is very similar to having jitter in digital transport. This will also impact audio clues for separation.

This has veered off into subjective territory and I’m unable to connect with your perception. Could you explain what is in the glass wall that makes the vocals sound harsh? Imagining that we have another person in the room talking, would they sound that way?

 

[matbhuvi]

This has veered off into subjective territory and I’m unable to connect with your perception. Could you explain what is in the glass wall that makes the vocals sound harsh? Imagining that we have another person in the room talking, would they sound that way?

Oh yes. Talking to a person in open ground, in room with high glass treatment and good treated room will sound different. Just that we don't put our audiophile hat in everyday conversations ( which is a good thing). But they all sound different

 

[Hari Iyer]

You are basically suggesting that, we can locate the source of a sound more reliably in a room, if the room has more reverberation. I think it should be the other way around. If you don't mind can you post which part of Tooles book mentions this?

I never mentioned any reverberation at all. I only told if 100% of the sound is absorbed, you won't locate the sound source as in an anechoic chamber. You will need to balance how much reflection is ok for your seating position. Typically diffusion at 1st reflection gives perfect balance of direct and reflected sound and hence more preffered.

 

[Passive_audio_enthusiast]

I only told if 100% of the sound is absorbed, you won't locate the sound source as in an anechoic chamber. You will need to balance how much reflection is ok for your seating position.

So in an anechoic chamber you will not be able to tell from which direction the sound is coming from? There are no reflections and reverberations present there.

 

[Hari Iyer]

I am confused, all concerts are in huge stadiums with banks of speakers. You can always tell the direction from which the sound is coming from. I was in a wedding recently in a mini stadium sized ground and the hosts decided, unfortunately, to put the panditji's slokas on a large speaker system. I had to move away at-least 500m to avoid the unpleasant loudness coming from those speakers in such a large area - from a direct recitation into a mike/amplifier. I don't think direct sound needs any reflections, it will always have a directional cue of source. And I agree cues are added to a recording by the engineer based on required results. It is not always reflected sounds. Like capturing cues of the recording location - like a jazz club or a church or whatever by mike placement etc.
Anyways I belong to the camp that the room is the most important component in any domestic system, and its treatment or lack thereof will make a big difference in the sound regardless of large or small size. Yes too much or too less treatment will make or break the sound but that is like any other component of the system. There has to be some balance.
Cheers,
Sid

Large concerts in an open stadium is a >60% a diffused field and there is not much absorption. The best imagination is an anechoic room. If you happen to be at Mumbai, you visit the IWAI factory at Vasai, Thane dist. There they have an anechoic room to measure their drivers. I had the opportunity to visit their factory in 2012 and also visit their anechoic room. We were speaking inside the room for around 15 minutes and we could barely hear the conversation even when speaking loudly. Also the ambient noise was scary low. I could not bare to be inside that room over 15 min TBH. Moreover the room was also painted black adding to the suspense.
PS:
Bose in their 901 speakers use the reflection to create ambience and
direction cues. Most concert halls use more of reflection and diffusion than absorption. A ratio of 25% absorption, 25% reflection and 50% difffusion is good for me. YMMV.

Diffisure not be commercial, but a simple lamp shade or a flower pot can also act line a sound disfigure.

 

[sidvee]

Large concerts in an open stadium is a >60% a diffused field and there is not much absorption. The best imagination is an anechoic room. If you happen to be at Mumbai, you visit the IWAI factory at Vasai, Thane dist. There they have an anechoic room to measure their drivers. I had the opportunity to visit their factory in 2012 and also visit their anechoic room. We were speaking inside the room for around 15 minutes and we could barely hear the conversation even when speaking loudly. Also the ambient noise was scary low. I could not bare to be inside that room over 15 min TBH. Moreover the room was also painted black adding to the suspense.

I used to work in the automotive industry in the US for 20 years. For NVH testing (noise, vibration, harshness) testing, my company had state of the art An echoic chambers maybe 40,000-50,000 sq,ft, wherein we could drive a car/truck in, put it on a cnc controlled platform, shake the crap out of it, to hear where the noise was coming from. If there was no way to hear where the noise was coming from, how would this work? Anyways it is what it is, I think your analogy is not clear. I am no expert in this, I may be wrong.
Cheers,
Sid

 

[Passive_audio_enthusiast]

This has veered off into subjective territory and I’m unable to connect with your perception. Could you explain what is in the glass wall that makes the vocals sound harsh? Imagining that we have another person in the room talking, would they sound that way?

glass reflects high frequencies more. we hear the direct sound from the speaker followed by the reflected sound from surfaces in the room. If there is too much glass around, it absorbs bass more but treble region alot less making it sound very bright. Good speakers reproduce voices as much as close to real life. So with those, the treble boost you get on vocals, will be similar to how a persons sound would sound in a room with lot of glass. However many speakers we buy already have problems with upper midrange area. If it has bad directivity the ability to fix this via eq is also not present. See this graph to understand how different materials absorb sounds https://www.engineeringtoolbox.com/accoustic-sound-absorption-d_68.html

 

[Passive_audio_enthusiast]

Oh yes. Talking to a person in open ground, in room with high glass treatment and good treated room will sound different. Just that we don't put our audiophile hat in everyday conversations ( which is a good thing). But they all sound different

we do not actively notice this, but yeah its completely true. I sound the best to my ears in the shower