Sound system settings before the concert

[Nick H]

We may wish for comfort and luxury, but even an autorickshaw will get us to the concert hall.

Unless there is any glaring deficiency in the equipment, I completely agree: it is the human controllers that count. I don't think any of would mind the improvement of high-class, properly set up equipment, just as we might prefer a Honda Accord to an auto, but it would be utterly wasted on ill-informed knob twiddlers.

[Babu]

I do hope many sound engineers and technicians read this thread and appreciate our concerns. I will be very happy if this thread has done an iota of awareness for making concerts enjoyable with proper setup before the concert and any minor adjustments during the first song. I agree with Ragam-Talam that this thread belongs in Technical or General discussions. Thanks and regards.

[Nick H]

I do hope many sound engineers and technicians read this thread and appreciate our concerns.

I fear that many of them are just guys doing a job, rather than rasikas. They would probably rather not read about work when they are not working!

[VK RAMAN]

Instead of blaming pakkavadyam, we are now talking constructive fixes. Let the organizers and administrators of concerts bring to sound engineers attention the valid points we are discussing. We can immediately see some improvements

[ragam-talam]

I fear that many of them are just guys doing a job,

Nick, your above remark triggered a thought...it seems men dominate the 'sound engineer' role at concerts! I am yet to see a woman at the audio controls. Perhaps they can do a better job at this?
Arasi, your thoughts?

[Nick H]

Oh... I don't think women can work that many knobs... and are they safe with electricity?

<JUST JOKING>

But with some seriousness too: it probably is just a matter of gender stereotyping. Apart from the sheer weight of a big PA speaker, there can't possibly be any good reason why it is always men. and even the physical strength difference is overstated.

Do women have better hearing than men? VKV will be able to tell us if there is a scientific difference. I know my wife (on a home-made playing tones on the PC test) has a huge frequency range, but then mine is rather challenged.

[VK RAMAN]

pampu kaathu - whose is prominent

[cacm]

Oh... I don't think women can work that many knobs... and are they safe with electricity?
<JUST JOKING>
But with some seriousness too: it probably is just a matter of gender stereotyping. Apart from the sheer weight of a big PA speaker, there can't possibly be any good reason why it is always men. and even the physical strength difference is overstated.
Do women have better hearing than men? VKV will be able to tell us if there is a scientific difference. I know my wife (on a home-made playing tones on the PC test) has a huge frequency range, but then mine is rather challenged.

THE ANSWER IS NO! But wives are typically YOUNGER & hearing range is age dependent. Also among musicians women tend to be more disciplned technically and mistakes at higher srutis are more easily noticeable. So they are as a rule BETTER in this aspect unless men are very particular like MMI. Men hide under the guise of being more original, creative while flouting the fundamentals of sruti, swarasthanam etc......VKV

[mohan]

Given the limitations of halls and the available sound system, organisers need to allow ample time to arrange and test the sound system before a concert. On many occasions I have heard that the organisers book the hall for only 1 hour before the concert start time and expect the audience to be allowed in 30 minutes before the start. Thus it leaves, only 30 mins to set up the sound and do the sound check!

Musicians should understand that for concerts (especially held outside India) the sound technicians are not doing Indian music everyday and hence they should be willing to do proper sound testing. In fact, the musicians should be proactive in insisting they need a sound test well before the concert start time!

[cacm]

It used to be that organisers like me, vvs, toronto venkataraman used to carry our hi-fi systems including speakers set it up ourselves & NOT use the system available in the hall in the sixties & seventies in N.A. After the concerts started being held in N.Y.Philharmonic hall in the seventies etc we insisted on a rehearsal session ahead in which problems are ironed out. one can notice the quality of recordings of LGJ, RAMANI & others from that period.....If efforts & time are not spent results can be disappointing. Now a days I feel in usa things have reverted to MADRAS LEVELS in many aspects including this.....VKV

[rungun]

Hi All
Rather interesting article and thread. I just came across this article. I do have to say that reading this has made me relate to the "Good" and "Bad" concerts in which I have managed the sound system.
I am one of those "sound engineers" that most of you are talking about and I thought I will try to give a brief description of my experiences. (All my Carnatic Music Sound arrangement experiences have been in the US and not in India - so read my comments with this in mind)
I will try to keep it in general terms, but that will do some injustice to the technology and what might be involved.
Hardware:
1. Mixer - generally used to mix the sound from each mike. It provides the capability of controlling the volume of each mike, provides the ability to change the bass/Mid/Treble (breaking this range of frequencies into anywhere from three to five ranges). It also lets you group the mikes into sub groups. In addition it typically provides a main output for speakers, an output for monitors and auxiliary outputs for use with recording, for providing effects like reverb etc, for use to compress sound etc.) Most mixers will provide controls to independently change the audio mix in the speaker, monitor and auxiliary outputs. Sruti box can be hooked up directly just like a mike, though very few artist in my ten years of experience have used this option.
2. Microphones - If I can generalize they can be either condenser or regular. In addition microphones have different frequency ranges and polar patterns (regions where they pick up sounds well). In general I prefer to use the carotid for vocalist so they can move their head and still have more or less the same sound level. For details on mike see http://en.wikipedia.org/wiki/Microphone. Instruments with pickup microphones can be handled like most mikes as long as the signal level match the mixer input. If there is a signal level difference one will have to use a Direct Input box to match this level.
3. Power Amplifier - To amplify the sound typically coming from the mixer. These are needed because the big speakers need a lot of power (Watts) to drive them. Small mixers are generally NOT designed to deliver the large power requirement.
From my memory of working with PA in my school days in India, many places use an amplifier that is equipped to have mike inputs with level control for each mike. (Some of these are called Powered mixers, but the ones I used in India were not so detailed designed). Finally they have another level control for the speakers. (I would never be the sound engineer if I have to use these for a Music Concert, they are good for speeches – End of Story)
Auditorium:
Like many of you have said, these can vary very widely. When the acoustics of the auditorium are designed well, it is a pleasure for the artist, audience and sound engineer. But the auditorium is not designed well; it can be a nightmare for everyone involved.
Sound setup (general): The sound setup can be in one of two ways (in my opinion). The same audio mix provided to both the monitor (stage speaker for artist) and audience or house speaker. (Several artists prefer this, but it comes with the downside that the volume change on any mike will be reflected in the total sound). The audio mix is different for the monitor and audience. (Generally takes more time to setup. I start with both monitor and house having the same levels and then fine tune as part of the sound check before concert). In either set up the volume control is independent for house and monitor. As part of the sound check the artist are given an opportunity to listen to only monitor and only audience and finally both. (Yes three different sounds)
Sound Check Before concert:
As the sound engineer for almost ten years, I insist with the artist that we must have a sound check before concert. (As I am part of the organizers – I do not have trouble with organizers. With artist it varies widely – some just tell me they will tap the mike and want nothing else. Some artists are wonderful and will work as a team with me and spend close to an hour). I generally try to dedicate at least one hour for sound check. Like several people mentioned in this thread, I carry the whole sound system for each concert and set it up. It takes me about an hour and half to setup five mikes, two stage monitors, two house speakers and a computer using the auxiliary outputs to record the whole concert.
I start by testing each mike and set the gain (read volume) levels to the artist’s satisfaction. During this time, all other mikes have been muted. Once all the mikes have been set individually, I request the artists to sing or play together as in the concert and make finer adjustments till the artists are completely happy with the mix both on stage and for the house. During this time I also increase the monitor volume to the maximum level so I actually get the “screech” feedback noise and mark the level. During concert this level should never be exceeded. In my experience as a sound engineer – almost all the concerts never have the famous “screech” during the show. During the sound check I make it clear to the performers on stage that I will only take instructions from the lead artist to change the sound levels during concert. (I am a little flexible, but generally take cue from the lead artist). During the concert I walk around the house to get a good feel for the sound and make minor adjustments for the house only.
The mixers let me use my headphone and listen to the level of each mike or any combinations of them during the concert and fine tune the gain levels if ever needed. Generally I have not found the need to adjust levels when we have done a thorough sound check. I use this feature of the mixer to also change the levels in the recordings and so in rare event that I have a loud mrudangam, my recordings still turn out to be well balanced.
Lastly there is an additional equipment available called “audio compressor” that is used for instruments that have a very high and low volume – like the mrudangam. Think of these as volume control that reduce the volume when it is too loud or increase the volume when it is too soft, but otherwise stay at the volume levels you initially set it up for. I do not use these, but have been considering in investing in one. If anyone wants details I can explain it more details.
For the equipment I am using the current cost is roughly as follows
Mixer – about $1500, Power Amplifier – about $400, Each mike about $100, Each monitors about $150, and each speaker – about $400. Remember that these are one time investments and last a long time. Most of the equipment we use is about 10 years old, but the cost above is current retail in the US market.
If people have more questions I will be happy to address them.

[Nick H]

Thank you for a detailed post describing the actual experience.

The only point I would pick on is taking instructions from the stage to change house levels. This, to me as a concert goer, is often the cause of my discomfort.

[rungun]

Nick

Thanks for your comment.

Maybe I missed the point in my long writeup, but NO I do not take instructions from the stage during the concert for house levels. It is done in the beginning as part of the sound check. I strongly believe that the artists on stage are Professionals and I also believe that they do clearly make this distinction about house levels. Without fail, the artists on stage have always told me that I am in charge of the house levels once the concert begins. Some of you may beg to differ, but I consider the artists on stage as members of THE TEAM as far as "aural aspect of sound" goes in the "pre-concert" sound setup and check. I make up the technical part in the pre-concert sound setup. I respect their input and take it based on a pecking order (Lead artist inputs are more important, than the accompanying artists and so on. I have had lead artist designate another member on stage and at time another person in the audience)

When the artists do not want to invest the time for pre-concert sound check and then complain about the quality - I ignore them by telling myself that these people are non-professional and lack professional ethics for the career they undertaken. In fact I have known Indian Artist who will clearly not agree to spend even a minute for sound check with me (Indian Organization), but spend any length of time when they are dealing with "Non-Indian Organizations" and that too without any objection what so ever. (Double Standards) I know this because I work very closely with many the sound and light engineer of presenting organizations in the Greater Philadelphia area and have experienced it personally.

Here are two comments that I am sure people might enjoy

1. When I requested an artist to give me at least some time for pre-concert sound check the conversation went as follows
Me : We will need at least 30 minutes for a sound check before the concert.
Artist : What is the minimum time you do with?
Me : at least 30 minutes for a decent sound check and I could manage with about 20 minutes if we are really short on time
Artist : Well then you can take thirty minutes for your sound check, but we do not need any. So when you are done let us know and we will start the concert, just tap the mike and begin. We will try to adjust the sound during the varnam. We always do this - so why are you special to have a sound check.

2. During another concert a very senior vocal artist arrived late due to several reasons beyond everyones control, but took it out on me and that too during the concert after the Varnam
Artist : Why is the violin louder than my voice? (Note : it was well balanced from my perspective as a sound engineer)
Me : Sir, it is exactly the same setting as we had when we did the sound check
Artist : So you do not understand what I am saying.
Me : Sir, I can increase your volume if you like, but we cannot hear the violin
Artist : then please do that.
After some more changes to the levels in the monitor, the artist threatened me by saying I will get up and go if you cannot set the sound right. The violinist, clearly understood my situation and moved away from the mike and we had a half decent concert.

[Nick H]

Maybe I missed the point in my long writeup, but NO I do not take instructions from the stage during the concert for house levels.

No, the point missing was all mine, as per marked in bold. :$

I'm sure the conversations and circumstances you report are not that uncommon, but working with the more professional and cooperative artists must be a real pleasure.

There's a question I'd like to ask you, and it is about the two-microphone thing. Some artists seem to equate the number of mics with importance, and some feel that two mics means double the power. I've hung around (being friends with the accompanists) many an arrengetram preparation in London, and a lot of parents seem to be of the opinion that it is something that their child "needs" (my opinion is that they should have been taught to project their voice, just like any student at a drama school is, but that is not yet recognised in carnatic music it seems).

I've read (but not properly understood) that two microphones can actually cancel each other out. On the other hand, if properly placed, do they permit a wider angle of capture for the artist who cannot (and should not) be expected to keep his head still?

And a by the way... do you cringe every time someone taps their (or rather your) microphone?

[rungun]

I'm sure the conversations and circumstances you report are not that uncommon, but working with the more professional and cooperative artists must be a real pleasure.

Yes it is a great pleasure and very satisfying. I love what I do (even though it is not for a living, but purely voluntary service) and try to educate myself and do the best I can. I take constructive criticism, but ignore the rest.[/quote]

There's a question I'd like to ask you, and it is about the two-microphone thing. Some artists seem to equate the number of mics with importance, and some feel that two mics means double the power. I've hung around (being friends with the accompanists) many an arrengetram preparation in London, and a lot of parents seem to be of the opinion that it is something that their child "needs" (my opinion is that they should have been taught to project their voice, just like any student at a drama school is, but that is not yet recognized in carnatic music it seems).

Based on my technical understanding of microphones - A mike with a Cardioid pickup pattern will generally be able to pick up most peoples voice with all the head shakes, as long as they do not move outside a cone with an angle of 120 degrees at the tip. Remember the tip is where the mike will be. In general they should be within a few inches of the mike all the time. From my memory even M. D. Ramanathan would have no problems if we had just one cardioid mike. No two microphones are not needed. I could be wrong, but based on my interactions with several carnatic music teachers - voice projection is something they do not spend a lot of time on. They teach the students to sing loud and clear, but not really in terms of voice projections which is typically done in drama schools.

I've read (but not properly understood) that two microphones can actually cancel each other out. On the other hand, if properly placed, do they permit a wider angle of capture for the artist who cannot (and should not) be expected to keep his head still?

As far as my technical knowledge goes, the two microphones cannot cancel each other out. Your second comment about the wider angle is true though, but remember that the gains for each mike will finally dictate how they perform and will be heard. (I hope this makes sense)

And a by the way... do you cringe every time someone taps their (or rather your) microphone?

I maybe an exception here - I do not cringe, because the mesh cover is designed to take a fair amount of tapping and abuse. (I have sent an e-mail to Shure - Mike makers to confirm the tapping issue. Will post the reply) Depending on how they tap, the sound created on the speakers, recording levels etc can be very annoying though and then I cringe.

[rungun]

All

Just got an e-mail from Shure customer support and they confirm that "tapping" the mike will not harm it. But as the owners of the mike you may have a different view and in my opinion that should be respected

rungun

[sramaswamy]

Thanks for the wonderful writeup and details. Here is a question I have. Pardon me if it sounds dumb (I made a pun to compensate ) . But one thing that I am not able to understand is why do we need to set the sound levels everytime. I can understand if it is a different auditorium and different mikes. But if everything except the artistes is same, do the vocal and instrument volume vary so much that you need to start from scratch each and every time?

[VK RAMAN]

Will the system allow recording also at the same time?

[rungun]

sramaswamy :But one thing that I am not able to understand is why do we need to set the sound levels everytime. I can understand if it is a different auditorium and different mikes. But if everything except the artistes is same, do the vocal and instrument volume vary so much that you need to start from scratch each and every time?

Ramaswamy - You are correct in that you will certainly have to setup the levels if the auditorium is different.

Even if you have a permanent sound system setup in an auditorium and the same set of artists are going to perform - one will have to fine tune the sound for the day of the concert. Let me try to explain in simple terms. Sound is produced due to vibrations that are carried by the air around us. These vibrations are picked up by the microphone which is then amplified. Now properties of the air that carries vibrations is very dynamic and changing all the time. (The room temperature moisture, Warm bodies who absorb these vibrations etc.) So yes one will have to correct the levels for these factors.

One change that comes to mind between various artists is the "kattai" they sing in and the volume that they sing at. Some sing softly, some instrumentalists play softly too. So these factors also make it necessary to change the levels.

Your last question about starting from scratch - personally I feel that is a better approach, because then if I run into a problem I know I have done my setup properly and know where to start debugging or trouble shooting. Also for us we are renting the auditorium for each concert and so we have to setup the sound each time from scratch.

VK Raman : Will the system allow recording also at the same time?

Some mixers provide a RCA output specifically for recording, while some of the newer mixers provide USB and Firewire outputs for connecting to computers. In our system - I connect one aux output to a digitizer to record on the computer and another aux output to record the audio only on a VCR. (VCR in long play provides up to 6 hours of recording, with a very small loss of quality. This way I have the concert recorded without any break.) I record concerts only when we have written permission from the artists or their agents.

Recording carnatic music is a whole another topic by itself. From analyzing many CD that I have bought from touring artists - I feel there is a general lack of understanding the technology specifically for the purpose of recording and publishing CD for the public at large. You hear a lot of sound saturation in these recordings.

[Enna_Solven]

Recording carnatic music is a whole another topic by itself. From analyzing many CD that I have bought from touring artists - I feel there is a general lack of understanding the technology specifically for the purpose of recording and publishing CD for the public at large. You hear a lot of sound saturation in these recordings.

Having bought hundreds of CD's and transferred them to lossless audio on to my computer, I wondered that why did I bother with lossless compression with some of the CD's. The audio is so saturated in a studio recording. Malladi brothers Krishna Leela Tharangini CD's nfor example.

As VKV said in a different post, recording of LGJ/NR during their 1970's US concerts by dedicated amateurs is much better!!

[rungun]

Having bought hundreds of CD's and transferred them to lossless audio on to my computer, I wondered that why did I bother with lossless compression with some of the CD's. The audio is so saturated in a studio recording. Malladi brothers Krishna Leela Tharangini CD's nfor example.

As VKV said in a different post, recording of LGJ/NR during their 1970's US concerts by dedicated amateurs is much better!!

I think VKV hit the key word "dedicated amateurs", but I would also add "dedicated knowledgeable amateurs". I have a few recordings from the 1980's of US concerts by dedicated members which do show audio saturation. In fact I balk and criticize myself at some of my concert recordings done in the first year I managed sound, but I think I have learned a lot along the way.

Enna Solven

By my analysis and understanding - audio saturation occurs because the loudness of how the artists perform changes as the song OR concert OR recording progresses. They get warmed up and almost unknowingly their volume goes up (One way to control this is to give them a proper monitor so they have a good feedback). This again brings my earlier comment about sound check - it is very important to set the audio levels for each mike even for studio recordings. Most mixers have a set of lights that show levels and when we set the sound we should request the artists to give us their loudest output and set the gain/levels so it reads "0 dB" (zero decibel). This gives a enough headroom/legroom (lingo meaning - more turns left in the knob OR more sliding available to change volume) as the concert/recording etc proceeds.

If I may say "The best audio compression is No Compression". Any compression will automatically mean some loss. Having said that, every software that is released for audio compression uses some technique to reduce the file size. What they do to reduce this is many times proprietary and we the general public will not know how they achieved the compression. Generally the compression is claimed to be lossless based on "aural feedback", or sometimes frequency spectral analysis. Many a times what is thrown away OR sacrificed is the very high frequency end and low frequency end. From my medical understanding - The reasoning for this is that from the day we are born, our hearing starts to degrade and never stops degrading. We human beings generally keep losing the low and high end almost constantly even though it may be just minimal each passing year.

rungun

[srikant1987]

Any compression will automatically mean some loss.

No, it doesn't. If it did, you'll get spelling mistakes if you compressed a text file and uncompressed it back again.

[VK RAMAN]

I think we are discussing about audio compression and not text

[rungun]

Sreekant

I think VKV made the point correctly. Text compression is very different from audio. Text compression uses the fact that you have the same words repeated in many places. In simple terms if I can take out words that occur many times and store it only once, and then put a marker where ever it occurred in the document I have achieved some compression. One easy way to understand this - take your newspaper, magazine and look at a page and you will that words like "the", "it", "is","if" etc occur way too many times. Replace all these occurrence and come up with a way of putting them back when you uncompress the file.

rungun

[rajeshnat]

rungun
You have lot of interesting points, I need to ask few questions there bit later. I have not got what you and ES mean by "audio saturation"?

[Nick H]

Text compression is very different from audio.

not necessarily. There are two kinds of compression: lossy and lossless.

Lossless compression techniques [should] recreate the exact same file when uncompressed. This is the same as compressing text or any other kind of data. All files on a hard disk are binary data, whether they represent simple text, a formatted document, a database, or pictures or music. All such files will have repetitive data patterns.

Whilst the lossy formats are great for carrying around in one's pocket attached to earphones, the lossless formats are plainly superior for archiving or even playing from the computer. They will not reduce as much, but then... people now have portable hardrives with more capacity than I used to administer across two or three corporate servers a decade ago.

Audio Saturation --- Does it mean compression in the audio, not data sense, ie loss of dynamics, ironing out of highs and lows? Testing myself here: rungun, you are the examiner, please!

how the artists perform changes as the song OR concert OR recording progresses. They get warmed up and almost unknowingly their volume goes up

This is obvious to many of us in the audience, but It seems that many of your colleagues haven't realised it! It is common to see the sound man sitting back reading a book, or abandoning the mixer altogether after the first item. They see to be under an impression that the levels set are set in stone and not to be changed, regardless of the warming artist or the filling hall

[rungun]

Nick: Audio Saturation --- Does it mean compression in the audio, not data sense, ie loss of dynamics, ironing out of highs and lows?

Nick, please do not call me an examiner, but in a sort of way it is ironing out of highs and lows. The ironing typically occurs because of the limitations of the electronics used.

I will try to explain Audio Saturation in non-technical terms. In science, we always think and visualize audio and sound as a wave. So if I am near a beach on a regular day, and let us say there is a steady breeze with no turbulence. The waves in the water will be nice and smooth with proper up and downs (if you know a sine wave that is what it will look like). Now when the wind picks up but is still steady with no turbulence, the wave will grow bigger, but still be smooth. So the waves are smooth and just get bigger in proportion to the smooth and steady wind. Now lastly picture that I can somehow chop the top of all these smooth wave, that is you suddenly have a wave that seems to grow, but then has a flat top, and continues down where the original wave was and so on.

Now when I am recording, if I keep the volume at the appropriate level, I will get the full wave, but if I just increase the volume beyond a point, I will get the chopped wave. Many CD's actually have this chopped wave.

rungun

[Nick H]

Thanks for that.

I meant examiner as in helping me test my knowledge and learn. Please accept instructor, if preferred --- or perhaps just better-informed fellow forum member

[rungun]

Thanks for that.

I meant examiner as in helping me test my knowledge and learn. Please accept instructor, if preferred --- or perhaps just better-informed fellow forum member

You are welcome Nick. Anything is fine and it is a pleasure to help...
rungun

[Enna_Solven]

When rungun/I said 'saturation' we didn't mean data compression. My point was the quality of the original CD was so bad that I needn't have bothered trying not to lose any quality with lossy compression.

I will try to explain a bit in technical terms:
Input = singer's voice, from 0 amplitude to 100, her/his maximum sound output
Output = mike output -> preamp (or amplifier, let us leave out the mixer for simplicity) -> recording medium.

For each of the stages there is input and output and these two are governed by what is known as the transfer function and gain. Transfer function tells the relationship between input frequency and output frequency and gain tells us the relationship between input and output signal amplitude (level, loudness).

In an ideal case, the amplifier would respond linearly over the entire sound spectrum and for all volume levels. That is output will ALWAYS be 'x' times the input. But this is not physically feasible, so we have all these instruments that will behave linearly ONLY over a certain range of volume levels. (Let us leave out frequency response for now. I have become rusty over the years and don't want to say something wrong) This is a simple the gain curve. (I had to play with the axes to show the bend in the curve)

Code: Select all

O |                                        *
U |                                 *
T |                            *
  |                         *
P |                      *
  |                    *
U |                  *
  |
T |               *
  |
  |            *
  |
  |         *
  |
  |      *
  |
  |   *
  0 -----------------------------------------------
                  INPUT

So, as long as we make sure that the maximum input signal level to the preamp(amp) is not beyond the linear range then the output will remain 'true' to the input. Beyond that, clipping of the sound waves will occur as explained by rungun. If we record so that the VU meter never goes into even the yellow range, we can later play the music back at full volume. We will not hear any distortion and the mrudangam's "thalangu thitthom" will be a pleasure to hear.

My illustration is simplified but explains the basic concept of saturation.

(Aside: lossy = mp3 files, lossless=flac files. Compression ratio: cd to mp3 about 10 times smaller file size, cd to flac about half the size. In spite of 'OhO kAlamE,' I am still sensitive to loss in audio quality. I miss the CD richness if bitrate goes below about 190 kbps when I compare the cd and mp3 side by side. Sensitive, but no music in me, boo hoo. ;( )

[Nick H]

When rungun/I said 'saturation' we didn't mean data compression.

compression in audio terms (absolutely different to data terminology) means making everything loud.

That's a definition that will make you and rungun wince, I know . "Dynamic range compression" is how one google-found article mentions it. I can visualise what happens to the wave form --- but I'll leave further explanation to the learned!

[vasanthakokilam]

Nick, as in every field, some times the terminology does not make intuitive sense. In compression of the dynamic range, the difference between the high and low are compressed. There are obviously two ways to do that: The high can be reduced ( downward compression ) or the low can be raised ( upward compression ). The latter one is the oxymoron-ic usage

[Nick H]

That makes sense.

related is limiting. If the material is too quiet, we may want to digitally amplify it, but there may be peaks that would then "clip", so we amplify the whole piece, but with a limit.

This is, I guess, relevant to recorded sound rather than concert-hall mixing.

[Enna_Solven]

Nick,

This is what my old Yamaha receiver manual says:

"Dynamic range" is the difference between the maximum level and the minimum level of sounds. Sounds on a movie originally designed for movie theaters feature a very wide dynamic range. Dolby Digital technology can modify the original sound track into a home audio format with this wide dynamic range unchanged. Powerful sounds of extremely wide dynamic range are not always suitable for home use. Depending on the condition of your listening environment, it may not be possible to increase the sound output to a level as high as that in a movie theater. However, at the normal level suitable for listening in your room, the low-level parts of source sound often cannot be heard well because they will be lost among noise in your environment. Dolby Digital technology has also made it possible to reduce an original sound track's dynamic range for a home audio format by "compressing" the sound data.

MAX
In this position, a source encoded with Dolby Digital is reproduced in the original sound track's wide dynamic range to provide you with powerful sounds just like those in a movie theater. Selecting this position will be even better if you can listen lo a source at a high output level in a room specially soundproofed for audio/video enjoyment.

STD (Standard)
In this position, a source encoded with Dolby Digital is reproduced in the "compressed" dynamic range of the source that is suitable tor low-level listening.

[Nick H]

So, in practical terms, you can hear the dialogue without being deafened by the explosions!

[rungun]

Nick, as in every field, some times the terminology does not make intuitive sense. In compression of the dynamic range, the difference between the high and low are compressed. There are obviously two ways to do that: The high can be reduced ( downward compression ) or the low can be raised ( upward compression ). The latter one is the oxymoron-ic usage

Vasanthakokilam you described it well "High can be reduced" and "low can be raised".

Your Yamaha receiver manual has described it well, but it seems to have it specifically targeted to Dolby Technology

I like the practical terms...

Digital compression OR particularly Audio Compression in music terms and when applied to sound during concerts, playback and recording can be more complex than what is typically given in most equipment manuals etc.Another variation to this technology is called Limiting (which is another way to achieve this volume/gain control)

A simplified description : Let us say an artist can sing in a range of 2 to 10. Now the instrument player can play from 0.5 to 12, but most of the time plays his instrument in the general range of 2 to10. So the compressor's job is now going to be to wait for when his sound drops below 2, be sure that it is really below 2 and bump it up so it is consistently at 2, but be ready to do return the volume to normal when he does suddenly go above 2. A similar situation happens at the upper end. The compressor has to be waiting to be sure that he is playing above 10 and bring it down to 10. The compressor must also ensure that it drops volume level back to normal when the instrumentalists starts playing below 10.

The cost of compressor you can buy will largely depend on the "quickness" with which it can react to these high and lows and how quickly it can be return volume/gains to normal. The second part of the cost is in how they increase OR reduce the volume/gain when signal is below 2 and above 10

Lastly the normal range is settable, and the better quality compressor will also let you change the reaction time (Hey I sensed that volume has dropped below minimum OR gone above maximum) and also how long to take to change this volume. (I sensed it and now I will change the volume over the next one second).

The compressor must change the volume without the audience or the artist noticing it as much as possible and that is a big part of the cost in the design.

rungun